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2858 Paste Up 3 - Sinal de Trânsito

1. Ce CO 6 uL 9 A 9 ve C o 9 e o 9 e o O O o9 Seven aspect signal face layouts eo ce O 9 e Qe 9 TH o CAC 6660 cee 9 e 6 56 o9 69 o0 eo e Q o9 See 000 99 eo Eight aspect signal face layouts H 66 De o9 609 ooe o9 _ e6 Cee oo9 660 Cee 99 Z 1 D 7 TD e a lt o DT 600 00 COQ AUSTROADS 27 TRAFFIC SIGNALS Figure 5 17 Examples of non permissible signal face layouts 660 o9 e o eo oe 9 660 eee o 09099 e 9 t TH oo99 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 5 7 Sequence of Vehicle Signal Displays 5 7 1 Basic Sequence The basic sequence of vehicle displays within a signal face shall be Green to Yellow to Red to Green as shown in Figure 5 78 It applies to three aspect circular arrow or symbolic arrangements and four aspect arrangements with a green arrow where
2. 6 2 3 Crash Risk Factors eder be dogs ras does tan retiens 6 3 Phasing D sign 55258 he decked E 6 3 1 Through Phasing with Filter Right Turns 6 3 2 Leading Right Turn Phasing 6 3 3 Lagging Right Turn Phasing 6 3 4 Split Approach Phasing 6 3 5 Diamond Overlap Phasing 6 3 6 Lead Lag Right Turn Phasing 6 3 7 Repeat Right Turn Phasing 6 4 Left T m Movements i us eden MUR les RU Rs end 6 5 Pedestrian Movements 6 5 1 General PR 6 5 2 Pedestrian Movements at Intersections 6 5 3 Midblock Signalised Crossings 7 Location of Signal Equipment 7 1 Introduction cigas enire siartr e eet eee eae 7 2 Designation of Signal Faces 7 3 Signal Face Functions 24 54 Gace cocoa desde d ou rene dre dress 7 4 Signal Face Site Requirements 7 4 1 Recommended Minimum Number of Signal Faces 7 4 2 Dual Primary Signal Faces 7 4 3 Overhead Signal Faces
3. 7 4 4 Pedestrian Signal Faces 7 5 Positioning of Signal Equipment 7 5 1 Lateral Post Positions 2 444 s huge RR une he RR ORE nes 7 5 2 Longitudinal Post Positions 7 5 3 Collision Risk Reduction 7 5 4 Lantern Mounting Heights 7 5 5 Clearances from Power Lines 7 5 6 Lantern Aiming 2 ns oe ec m hmc EO ER EUR ERR de pet 7 5 7 Modification for Unusual Geometry and Other Physical Considerations 7 5 8 Other Street F rniture 22 254788 4 te Det te LACE re Da Rea tes 7 6 ISON S eta rv 7 7 OUVTES eL e eatin co gene eod ccc We ac a eccle se d acd dede site gei eser sie dd AUSTROADS 34 34 34 34 34 34 34 35 35 35 36 36 36 36 37 37 37 41 42 42 43 43 44 44 44 47 47 47 48 49 49 49 51 52 52 53 53 53 54 54 54 57 57 57 57 58 59 59 59 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 10 UcugndilconpnmMC 60 8 1 Tayifero reto LAC Re dr D I to ile id 60 8 1 1 Traffic Detection During a Signal Cycle 60 8 1 2 Vehicle Detection Modes 60 8 2 Types Of Trafic esiseina int demon ten wid dg ent 61 8 3 Vehicle Detection tos nr ce dun
4. C 5 2 Pedestrian Clearance Time C 5 3 Pedestrian Delay Setting C 6 Bicycle Settlligs ia cma ares colin mette ni ia AUSTROADS 107 107 108 109 109 110 110 111 112 112 112 112 113 114 114 114 115 116 121 121 121 121 123 123 123 125 127 127 127 128 128 129 129 130 132 133 133 134 134 135 xiii Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Appendix D Worked Example 136 D 1 hup 5 55 34 55 8 btw oth beet it A iii in INls 136 D 2 Input and Output Requirements 136 D 2 1 WUE DAS zie eed ebd x seme M mE EMI eb EARE 136 D 2 2 Output Information 137 D 3 Existing Geometry and Phasing 138 D 3 1 Description and Input Data for Design 1 138 D 3 2 Analysis Results for Design 1 140 D 4 Proposed Geometry and Phasing 141 D 4 1 Description and Input Data for Design 2 141 D 4 2 Analysis Results for Design 2 143 D 5 Implementation of Proposed Design 147 D 5 1 Provision of Signal Hardware and Location
5. OO QO O OO OIOI O al OO Ce e QO Q I No conflicting pedestrian or right turning vehicle movement AUSTROADS 33 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 5 7 5 Sequences for Two Aspect Columns The sequence requirements for two aspect vehicle signals where used as regulations permit are as follows a at ramp metering signals Green to Red to Green b TZ at roundabout metering signals Off to Yellow to Red to Off at far right secondary signals Off to Green to Yellow to Off at left turn slip lanes with signalised crossings Off to Yellow to Red to Off c d For pedestrian and bicycle signalised crossings see Sections 5 8 and 5 9 5 8 Pedestrian Signals 5 8 1 Signal Face Layout A pedestrian signal face layout consists of a red pedes trian aspect mounted above a green pedestrian aspect Figure 5 1 Pedestrian aspects must never be incor porated with vehicle aspects in a common signal face 5 8 2 Basic Sequence The basic sequence for pedestrian displays is Steady Red to Green to Flashing Red to Steady Red In some jurisdictions the red pedestrian signal is extin guished until the pedestrian demand is registered In this case the sequence for pedestrian displays is Off to Steady Red on pedestrian demand to Green to Flashing
6. to Lp Lv v a gt ty Ly V tg lt gt h ty t2 Where the traffic stream is represented as a mixture of light and heavy vehicles the average vehicle length representing the actual traffic composition can be calculated according to the proportions of these two classes of vehicles in the traffic stream For example using average vehicle lengths of 4 4 m and 9 0 m for light and heavy vehicles respectively the average vehicle length with 10 per cent heavy vehicles is approximately 4 9 m For general analysis purposes the effective detection zone length may be considered to be equal to the physical loop length The typical loop length used in Australia is 4 0 m or 4 5 m AUSTROADS B 3 3 Flow Rate Density and Occupancy Ratios Flow rate is the number of vehicles per unit time passing arriving or departing a given reference point along the road With queuing at interrupted traffic facilities demand flow rate can be measured as the arrival flow rate at the back of the queue Density is the number of vehicles per unit distance along the road as measured at an instant in time Time occupancy ratio is the proportion of time in an analysis period when the passage or presence detector at a point along the road is occupied by vehicles Space occupancy ratio is the proportion of a road section distance occupied by vehicles at an instant in time 115 Accessed by AR M VI
7. 24 AUSTROADS 25 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Permissible and Non Permissible Signal Face Layouts 5 6 Figure 5 15 summarises permissible three to six aspect signal face layouts for normal vehicles including the more common layouts discussed in Sections 5 3 to 5 5 Refer to Figure 5 6 for permissible two aspect signal face layouts Single aspect face layouts are not per missible except in rare circumstances Figure 5 16 contains examples of signal face layouts that are acceptable but should be avoided if possible Figure 5 17 shows signal face layouts that are not permissible Figure 5 15 Permissible signal face layouts Three aspect signal face layouts o Four aspect signal face layouts o9 606 o o OO e oe eo ee Five aspect signal face layouts o o eo o9 QO o9 Six aspect signal face layouts A 9 GO GO CO oe 9 oe e 0e 0900 6000 o9 26 AUSTROADS ed by AR M VICROADS on 02 Jun 2005 Access SIGNAL FACE LAYOUTS AND DISPLAY SEQUENCES Figure 5 16 Signal face layouts that are permissible but should be avoided if possible Five aspect signal face layouts H ceo e 69 o O C9 O o9 GC Six aspect signal face layouts
8. a Call activated when the train reaches a point approximately 35 seconds upstream of the crossing b Release Force goes off when the train activates the level crossing and on when the booms are nearly vertical c Pre Release indicates when the train is clear of the crossing and the booms start to rise d Booms Horizontal indicates that the booms are horizontal and e Cable Monitor permanently on to indicate that the cable is intact The time between the Call and Force inputs 35 seconds is based on whether the train is a stopping or an express train and the approach speed of the train It allows for the termination of all pedestrian and vehicle movements in the running signal phase transition to a track clearance phase and then starting a phase that does not conflict with the train movement s before the railway level crossing signals start operating AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 9 Signal Controllers 9 1 General The traffic signal controller is the equipment including the housing that switches power to the signal lanterns and controls the duration and sequence of signal displays This equipment is placed in a ground mounted housing or a post mounted housing Figure 9 1 illustrates how the controller interfaces to the other components of the signal system The physical characteristics of the controller are specified in AS 2578 9 2 Types of Control Operation of a
9. Figure C 3 Pedestrian and vehicle phase intervals at a Pelican crossing Start of Pedestrian End of Pedestrian Phase Pres pees Sn Phase Change Phase Steady Don t Walk Red Walk Green Flashing Don t Walk Red Steady Don t Walk Red Clearance 1 Clearance 2 lt Total Clearance Time All Red gt Vehicle Phase Pedestrian Intergreen Vehicle End of Start of Phase Vehicle Vehicle Change Vehicle Phase Phase Intergreen Green Flashing Yellow Green Yellow All Red gt Red 126 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 For parallel crossings at signalised intersections and subject to demand for another phase a phase will start terminating at the end of the i pedestrian Clearance 1 interval if the vehicle running intervals expire before or concurrently with it ii the vehicle running intervals if the pedestrian Clearance 1 interval expires before them For midblock signalised crossings and exclusive pedes trian phases at intersections the pedestrian phase will start terminating at the end of the Clearance 1 interval regardless of a demand for another phase The minimum phase green time due to a pedestrian movement is determined as the sum of minimum Walk Time and Clearance 1 interval time This will govern the minimum phase time when parallel pedestrian and vehicle movements operate concurrently and t
10. MTBF Mean time between failures a signal maintenance term MTTR Mean time to repair a signal maintenance term Negotiation Speed see Speed Ninety fifth Percentile Queue Length Queue length expected to be exceeded in 5 per cent of signal cycles only used for designing adequate queue storage length Occupancy Time The time that starts when the front of a vehicle enters the detection zone and finishes when the back of the vehicle exits the detection zone Thus it is the duration of the period when the detection zone is occupied by a vehicle Off Peak Period The periods that have low demand volumes of traffic during the day Also see Peak Period Offset The difference between the start or end times of green periods at adjacent upstream and downstream signals Opposed Turn see Filter Turn Opposing Movement 1 A movement that conflicts with and has priority over another opposed movement 2 Amovement which approaches from the opposite direction as another on the same road regardless of destination Outreach of Mast Arm The horizontal distance from the centre line of the vertical member to the centre line of the overhead lantern assembly Overhang of Mast Arm The horizontal distance from the kerb alignment to the centre line of the overhead lantern assembly Overhead Signal Face The signal face mounted above the roadway XX Overlap Movement A movement that runs in consecutive phases with
11. a a common system cycle time one half of the cycle time in the case of double cycling b green splits and c offsets A system cycle time can be selected by first determining an appropriate cycle time for each intersection in the area e g using the practical cycle time method see Appendix C Then the intersection with the largest cycle time can be designated as the critical intersection and its cycle time can be used as the common system cycle time Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Figure 13 1 Basic strategies for determining offsets for coordinated signals a Idealised coordination Es i li Distance How Bandwidth EE ee ee ee e 1 e2 e3 ea Eres pm A sn EE n D Reference intersection b Starting offset coordination Time a Bandwidth Distance Cycle time E ee e1 e2 3 e 4 Se LS ee sd el e E Reference intersection c Finishing offset coordination mi m Distance O gt 0 Bandwidth e 1 e2 3 ea NE Reference intersection 84 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 Some minor intersections in the area can be operated with a cycle time of half the system cycle time double cycling when it is found that this can reduce delay to side road traffic and pedestrians significantly without unduly increasing the number of stops on the main road Alternatively the coordination areas can be r
12. AS NZS 2633 1996 Guide to the Specification of Colours Traffic Signal Controllers Colour Standards for General Purposes AS 2700 1996 Acoustics Methods for the Measurement of Road Traffic Noise AS 2702 1984 AS 2703 1987 Vehicle Loop Detector Sensors AS 2898 1992 Radar Speed Detection AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 AS 2979 1998 AS NZS 3000 2000 Electrical Installations Wiring Rules Traffic Signal Mast Arms AS 4113 1993 AS 4191 1994 Traffic Signal Lamps Portable Traffic Signal Systems TAYLOR M A P 1996 Planning and Design for On Road Public Transport In Traffic Engineering and Management Eds K W Ogden and S Y Taylor Institute of Transport Studies Department of Civil Engineering Monash University Melbourne Australia Reprinted 1999 pp 335 355 TRANSIT NEW ZEALAND AND LAND TRANSPORT SAFETY AUTHORITY 1998 Manual of Traffic Signs and Markings Part I Traffic Signs Wellington New Zealand TRANSIT NEW ZEALAND AND LAND TRANSPORT SAFETY AUTHORITY 1997 Manual of Traffic Signs and Markings Part Il Markings Wellington New Zealand TRB 2000 Highway Capacity Manual Transportation Research Board National Research Council Washington D C U S A AUSTROADS REFERENCES U S DEPARTMENT OF TRANSPORTATION 1988 TRANSYT 7F Users Guide Transportation Research Center University of Florida Gainesville Florida U S A
13. advance loops are able to terminate phases earlier since assessment of gaps can be made several seconds before it can be detected at the stop line The following considerations also apply to advance detector loops i they are not as effective as stop line detectors in identifying turning movements if placed upstream of exclusive turning lanes ii demands lodged are processed on the assumption that vehicles do not change lanes or turn off before reaching the stop line iii vehicles entering the roadway between the detector loop and the stop line are not detected or vehicles leaving the roadway between the detector loop and the stop line are detected unnecessarily 8 3 4 3 Queue Detection Presence detectors in conjunction with a presence timer may be used to detect queues of excessive length A presence time is set e g 5 seconds and when the loop is occupied for longer than this set time a demand is registered Applications of queue detection include a registering a demand for a right turn phase by determining if the queue is too long to filter adequately see Figure 8 5 b TZ detecting critical storage conditions that require the cessation or introduction of certain phases for example i traffic blocking the middle of a major intersection ii queues on freeway off ramps that are likely to overflow onto the freeway iii queues on or near a railway level crossing Generally a
14. 147 D 5 2 Cable Connection Design 149 D 5 3 Selection of Controller Settings 149 References ae T ETE T NOE 153 Information Retrieval ccr ror a p e D o CR ROGER STER ERU C EU e RC e RR 158 xiv AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 Glossary of Terms Meanings given here may differ from Australian Standards AS 1348 1 and 1348 2 1986 Other sources are the Australian Road Rules NRTC 1999 US High way Capacity Manual TRB 2000 and various research reports Ak elik 1981 Ak elik Besley and Roper 1999 Acceleration Lane A paved auxiliary lane including tapered areas allowing vehicles to accelerate when entering the through traffic lane of the roadway Active Warning Device A device which changes state to display a warning of a hazard Actuated Control see Traffic Actuated Control Actuation The electrical action produced by a vehicle on a vehicle detector or pedestrian on a push button switch to enable the controller to recognise its presence Adaptive Engineering see Controller Programming Advance Warning Signals An active warning device consisting of a warning sign with Alternating Flashing Yellow displays to warn approaching drivers of their imminent arrival at traffic signal installation Algorithm see Controller Algorithm All Red Interval A period of time for the clearance of conflicting move m
15. See Section C 4 6 1 See Section C 4 6 2 and Table C 2 O 5 seconds 0 3 1 5 seconds 4 12 seconds 2 5 seconds See Section C 5 1 and Table C 2 See Section C 5 2 and Table C 2 O 10 seconds 122 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 SCATS Master Isolated Control Section 9 2 2 is basically an actuated control method but differs from the traditional actuated controller operation in deter mining appropriate green times on a cycle by cycle basis Ak elik Besley and Chung 1998 The traditional vehicle actuated control uses Maximum Green Settings i e maximum cycle time is not a setting SCATS Master Isolated Control determines green times using the equal degree of saturation principle subject to a specified maximum cycle time These green times act effectively as maximum green times and the actual green times differ from these values when the phase changes occur by gapping out Section C 4 4 Determination of appropriate cycle time and green times for coordinated signals is discussed in Section 13 2 1 C 2 2 Maximum Tolerable Delay Drivers and pedestrians will tolerate only limited delay at traffic signals particularly if a red display appears to be maintained needlessly Because of the inherent bounds of human patience drivers and pedestrians may disobey red displays if delays are abnormally long Therefore an upper time limit must be set to green time for any movement to
16. b TZ the major road or limited sight distance from the minor road causes undue delay or hazard to the minor road vehicles and there is no other nearby installation easily accessible to the minor road vehicles OR c Pedestrian safety For each of four one hour periods of an average day the major road flow exceeds 600 veh h in both directions or where there is a central pedestrian refuge at least 1 2 m wide the major road flow exceeds 1000 veh h in both directions and the pedestrian flow crossing the major road exceeds 150 ped h For high speed major road conditions where the 85th percentile speed on the major road exceeds 75 km h the above major road traffic flow criteria are reduced to 450 veh h without refuge and 750 veh h with refuge OR Crashes The intersection has been the site of an average of three or more reported casualty crashes per year over a three year period where the crashes could have been prevented by traffic signals and the traffic flows are at least 80 per cent of the volume warrants given in a and b Signals should only be installed if simpler devices will not effectively reduce the accident rate OR d Combined factors In exceptional cases signals occasionally may be justified where no single guideline is satisfied but where two or more of the warrants given in a b and c are satisfied to the extent of 80 per cent or more of the stated criteria e 1 5 2 Midb
17. b extra low voltage 50 Hz circuits for pedestrian push button demand indicators c circuits for vehicle detector outputs d digital data links associated with coordinated signal systems where dedicated cables or those leased from telecommunication authorities may be used The design function will need to provide details of duct sizes and access pits Cable connection charts are required to identify each core of each cable its function connection details and cable routing Such a chart is an essential document for installation and subsequent maintenance Adaptive engineering is required to enable the oper ation and maintenance of isolated or coordinated signal systems see Section 9 4 12 2 Installation All cable systems shall be installed to the requirements of the local electricity authority and the requirements of AS NZS 3000 This provides safety for both electrical workers and the general public In this regard specific attention must be given to a adequate buried depth of cable b earthing of signal hardware and equipment for electrical safety c adequate separation isolation insulation of 240V and other cabling d jointing of cables at terminal strips located on the top of signal posts and in either junction boxes attached to or within the cavity of joint use columns and mast arms e duct and access pit sizes to facilitate installation of cable 12 3 Cables Cables manufactured to th
18. electric light pole ELP and so on are shown in Figure D 1 The existing intersection is two phase operation with filter right turns as shown in Figure D 2 Peak hour traffic volumes for each approach and pedestrian volumes for each crossing are shown in Figure D 3 The filter right turn movements from both North and South approaches encounter heavy opposing flows and the right turn movement from North has high volume The site has a crash history of 8 right angle collisions and 2 right turn with opposing through collisions and the number of crashes has been increasing in recent years This trend is in line with increased right turn vol ume from the North resulting from the expansion of the shopping centre The two phase arrangement can no longer cater for right turn volumes against heavy opposing through APPENDIX D WORKED EXAMPLE Figure D 2 Signal phasing for Design 1 Phase A Phase B in New Zealand opposed by right turns fram West traffic flows as evident by very long delays experienced by right turning vehicles from North approach in part icular The current conditions Design 1 will be analysed with this problem in mind and then improvements to the intersection layout and signal phasing will be sought in order to improve the intersection safety and efficiency substantially Design 2 as discussed in Section 6 Figure D 3 Traffic volumes 1 Road 220 1200 77 10 125 8
19. o S 304 i 20 15th percentile o S 10 5th per centile O 00 0 2 04 0 6 0 8 1 0 1 2 1 4 1 6 1 8 2 0 2 2 2 4 Walking speed m s C 6 Bicycle Settings Two aspect bicycle signal faces used at midblock signal ised crossings or intersection signalised crossings are connected to the same signal group in the controller that drives the two aspect pedestrian signal faces In this case the pedestrian Walk and Clearance times apply to the bicycles as well Three aspect bicycle signal faces can also be used at signalised intersections In this case a For bicycle movements parallel with a main road and crossing narrow minor roads the bicycle signal faces are connected to the adjacent vehicle signal group and introduced with the green display for vehicles and terminated with the vehicle movement b TZ For bicycle movements across a main road and for those parallel with a main road and crossing wide minor roads the bicycle signal faces are driven by a separate signal group with green yellow and red times that reflect a bicycle speed of 20 km h AUSTROADS The following measures can be adopted in order to allow for slower speeds of cyclists compared with vehicle speeds see Austroads 1999 Traffic Engineering Guide Part 14 Section 5 4 3 i Adjusting the Yellow Time for the bicycle move ment to warn cyclists to stop before other traffic in the same phase i e increase the intergr
20. the number of possible alternative responses and the complexity of the response required Welford 1969 Measurements of actual response times to changes in traffic lights without any complicating factors has been found to be in the range 1 to 2 seconds The human system deals with stress situations in a complex way A conceptual model of the human decision making process is shown in Figure A 2 At point A the task is well within the ability of the driver but the demand for mental stimulation inherent in the human system forces him to adjust the overall task to point B by adding se f paced tasks such as listening to the radio or having a discussion with a passenger With an increase in the externally paced task demand the driver must first reduce the self paced task A further increase in the externally paced task demand brings the driver s performance to point C This may not be recognised by the driver who thinks his performance is at D This over estimation of his own decision making ability is a potentially dangerous human characteristic If the presentation rate increased to E it may only be the driver s skill in shedding redundant information or good fortune that may avert disaster A more detailed and informative treatise on this subject is given by Cumming 1964 Hebb 1955 postulated a relationship to explain how changes in performance result from changes in arousal as shown in Figure A 3 Arousal describes the general
21. 144 157 Parameters for queue discharge at saturation maximum flow Headway h s 1 75 1 77 Speed v km h 42 25 Spacing L m 20 4 12 0 Gap length L n m 16 0 7 6 Density k veh km 49 83 Occupancy time ton s 0 76 1 31 Space time t s 0 99 0 46 Time occupancy ratio O 44 74 Space occupancy ratio O 76 22 37 AUSTROADS 117 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Figure B 2 Spacing Ly and Gap length L m veh Spacing and gap length as a function of speed using average parameter values for through traffic lanes surveyed in Melbourne and Sydney vehicle length 4 4 m 50 40 30 20 Lsn 2160 10 L Lsj 2 6 0 I I I I H 0 10 20 30 40 50 60 70 80 Speed v km h Figure B 3 Headway time as a function of speed using average parameter values for through traffic lanes surveyed in Melbourne and Sydney 80 70 vf 69 0 60 B E 50 gt 401 42 1 o amp 30 20 10 hn 1 75 0 0 0 1 0 2 0 3 0 4 0 Headwaytime h s 118 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 APPENDIX B VEHICULAR TRAFFIC FACTORS Figure B 4 Occupancy and space times as a function of speed using average parameter values for through traffic lanes surveyed in Melbourne and Sydney vehicle length 4 4 m effective detection zone length 4 5 m Average Thru All sites
22. 2 OO O IET ce CC erer Q Q o 9 l mt 9 I Figure 5 23 Examples of display sequences to initiate an arrow controlled left turn movement During red circular display OORO 0 During green circular display Simultaneously with green circular display ee QO lt Displays where provided 32 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 SIGNAL FACE LAYOUTS AND DISPLAY SEQUENCES Figure 5 24 Examples of display sequences to terminate an arrow controlled left turn movement During red circular display E o ce OQO 090 00 Q QO OO During green circular display Ce GO eO OO 80 00 QO O09 Simultaneously with green circular display CY SO CO OO 60 OO CO OO OO lt Displays where provided Figure 5 25 Display sequences for four aspect arrangement with single red left turn arrow aspect for the protection of pedestrians or special vehicles With pedestrian or special vehicle demand Ce QO O NON Conflicting pedestrian movement OO Q e Without pedestrian or special vehicle demand Ce C Q al
23. 70 8 265 20 55 4 Side 50 Y 75 910 60 6 85 5 30 l 52 5 Street 220 15 65 7 y Main Light vehicle and Heavy vehicle volumes are shown for each vehicle movement Pedestrian volumes are shown for West North and East legs Vehicle and pedestrian demand volumes veh h and ped h shown are derived from 30 minute peak count AUSTROADS 139 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Various input data for Design 1 analysis are determined as follows a b TZ c d e 140 The volumes in Figure D 3 are peak 30 minute values though given as hourly flow rates i e twice the values of 30 min volume counts Therefore the Peak Flow Period for performance calculations is specified as 30 minutes and the Peak Flow Factor is specified as 1 00 There are no measured saturation flows available and hence they will be estimated by the program The site is in a suburban shopping environment Basic saturation flows of 1950 and 1800 through car units per hour are considered to be appropriate for the North South and East West roads respectively The intersection is in a 60 km h speed limit zone All approach and exit speeds are therefore specified as 60 km h All approach distances are specified as 500 m All intergreen times are 6 seconds They are determined using the method described in Appendix C Section C 4 6 l Urt where ty yellow
24. ARRB 16th Conf 16 5 pp 325 345 ARRB Transport Research Ltd Vermont South Australia 155 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS RTA NSW 1991 Traffic Signal Operation Document No RTA TC 106 Roads and Traffic Authority of New South Wales Sydney Australia RTA NSW 1991a SCATES User Manual Roads and Traffic Authority of New South Wales Sydney Australia RTA NSW 1992 Traffic Signal Practice Design Roads and Traffic Authority of New South Wales Sydney Australia RTA NSW 1992a Portable Traffic Signals Guide To Use Roads and Traffic Authority of New South Wales Sydney Australia RTA NSW 1993 Guide to Traffic Generating Developments Roads and Traffic Authority of New South Wales Sydney Australia RTA NSW 1998 Bus Lanterns at Signalised Intersections Technical Direction 98 4 77M1776 Roads and Traffic Authority of New South Wales Sydney Australia SIMS A G 1979 The Sydney Co ordinated Adaptive Traffic System Proceedings of the Engineering Foundation Conference on Research Directions in Computer Control of Urban Traffic System ASCE New York pp 12 27 SIMS A G and DOBINSON K W 1979 SCAT The Sydney coordinated adaptive traffic system philosophy and benefits Proceedings of the International Symposium on Traffic Control Systems Vol 2B pp 19 42 Univ of California Berkeley SMITH G and WEIR R 1975 Visibility Studies of Symbols Us
25. Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 14 3 7 Cleaning and Painting Signal hardware should be kept clean and where necessary painted by routine maintenance Cleaning of lanterns is important in maintaining light output although the required frequency is related to the environment 14 3 8 Spare Parts Maintenance planning must consider the availability of spare parts Stocks of expendable items such as lamps will differ from those such as controllers that are recyclable operational spares Items which are unique to the industry or which have long delivery times should be stocked in sufficient quantity However having regard to average failure and repair rates a 10 per cent spares holding is generally satisfactory 94 14 3 9 Replacement Scheduling While maintenance activities aim to keep equipment operational the rate of failure of components generally tends to increase as the equipment ages After a period some specialised components may be either with drawn from manufacture or manufactured in reduced quantities These then become harder to acquire and more expensive with the net result that maintenance costs rise Advances in technology also render older equipment increasingly unsuitable for the operational demands made upon it This together with rising maintenance costs eventually makes replacement with new equip ment necessary Reliability engineering techniques can assist in identifying the econ
26. Figure 5 22 shows a special display sequence using a four aspect arrangement with a single right turn red arrow aspect as discussed in Section 5 4 3 This figure shows initiation and termination of a filter right turn movement 5 7 4 Left Turn Sequences Display sequences to initiate and terminate arrow controlled left turn movements are illustrated in Figures 5 23 and 5 24 respectively Figure 5 25 shows a special display sequence using a four aspect arrangement with a single left turn red arrow aspect as discussed in Section 5 5 3 This figure shows initiation and termination of a filter left turn movement Figure 5 19 Examples of fully controlled right turn display sequences for six aspect arrangements Right turn arrow displays change simultaneously with circular displays right turn and through movement initiated and terminated at the same time OO OO Te f Right turn arrow and circular displays change at different times terminating the right turn movement and initiating the through movement e e OD OO IN Right turn arrow and circular displays change at different times terminating the through movement and initiating the right turn movement OD OD OO le Te ft OO 69 OQ 00 OO gt 090 gt ev OO O OO Ir Te 69 Oo OO 9 0 OO eo Ir lc ev eo
27. M VICROADS on 02 Jun 2005 Cycle Length Cycle Time Time required for one complete sequence of signal displays sum of phase green and intergreen times For a given movement cycle time is the sum of the durations of red yellow and green signal displays or sum of Effective Green and Red Times Degree of Saturation The ratio of arrival demand flow rate to capacity during a given flow period Delay The additional travel time experienced by a vehicle or pedestrian with reference to a base travel time e g the free flow travel time Demand The registration of the presence of vehicle or pedestrian traffic waiting for the right of way Demand Flow Demand Volume The number of vehicles or pedestrians arriving during a given period as measured at the back of queue as distinct from departure flows measured in front of the queue Also see Flow Rate Traffic Count Traffic Volume Density The number of vehicles per unit distance along the road as measured at an instant in time Design Life The number of years into the future while the inter section operates satisfactorily considering increases in traffic demand volumes Detector A device by which vehicle or pedestrian traffic registers its presence The most common detectors are the inductive loop detectors for vehicles and the push button detectors for pedestrians Other detector types include microwave radar infrared sonic video image processing magnetic and pr
28. by vehicles at an instant in time Space Time The time between the detection of two consecutive vehicles when the presence detection zone is not occupied It is equivalent to gap time less the time taken to travel the effective detection zone length Spacing The distance between the front ends of two successive vehicles in the same traffic lane Special Vehicle Aspects Signal aspects for special vehicles bus tram emergency vehicle consisting of red yellow and white B T and E symbols Also see Special Vehicle Signal Face Special Vehicle Signal Face A single column signal face for the control of special vehicle bus tram emergency vehicle movements Also see Special Vehicle Aspects Speed Distance travelled per unit time In a time distance diagram the slope of the trace of a vehicle is its speed Approach Speed is the uninterrupted midblock cruise AUSTROADS GLOSSARY speed of vehicles before being affected by traffic signals This can be represented by the speed limit Negotiation Speed is the safe speed of a vehicle moving through the controlled area of the intersection For turning vehicles this can be determined as a function of the negotiation radius Eighty fifth Percentile Speed is the speed at or below which 85 per cent of the traffic travels Split Approach Phasing The signal phasing arrangement that allocates separate phases to opposing approaches allowing the through and all turning movements fr
29. detection zone does not encroach on other lane are recorded and that information specific to the streams site is documented complete documentation is d check pedestrian push button assemblies to essential to facilitate maintenance verify the operation of pedestrian indicators n check that the lane configuration and pavement orientation of the arrows the audio tactile markings are in accordance with the design plan operation including sound levels and the Sections 3 and 10 connection of the audio tactile functions to the correct Walk displays o check that the required signs have been installed and redundant signs removed Section 11 e energise the controller but with lamps circuits off and check the operation in response to demands p have the kerbside controls been installed from vehicle bus tram and pedestrian detectors q check that the fault reporting sign has been where special detectors e g for fire stations and installed on the signal controller Section 11 3 13 trains are provided these should be similarly checked and detector presence times should be checked Accessed by AR M VICROADS on 02 Jun 2005 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 14 2 Monitoring and Evaluation of Operation 14 2 1 General Following implementation and fine tuning of signals monitoring and evaluation of the operation will verify or otherwise the adequacy of assumptions made in the design Inade
30. example arrow legends point horizontally on the push buttons b Wide Midblock Signalised Crossing in this example arrow legends point upwards on the push buttons 54 7 5 Positioning of Signal Equipment The conspicuity of traffic signals is influenced by a combination of factors such as signal colour intensity size background luminance and exposure time as well as the location of the signal in the driver s visual field Figure 7 5 a illustrates driver lantern visibility templates for use on signal layout design plans to determine if lanterns are located sufficiently close to the driver s line of sight Figure 7 5 b illustrates a typical application of a visibility template The number of signal posts should be minimised for safety and aesthetic reasons e g pedestrian and vehicle signals can be mounted on a common post or vehicle signals for different approaches can be mounted on a common post The recommended positions for signal posts and mast arms are detailed below It is important that these positions satisfy the requirements of the Commonwealth Disability Discrimination Act 1992 and AS NZS 1428 Mast arms are rigid structures and they should only be located where the probability of impact by vehicles is low AS 2979 7 5 1 Lateral Post Positions Kerbside posts and mast arms should be positioned nominally 1 metre from the kerb face but not closer than 0 6 m Median posts sho
31. greatest visual range Circular aspects control all traffic approaching or waiting at the stop line associated with those aspects if they are the only aspects in the signal face At an intersection a circular green display permits left turning and right turning traffic to filter accept gaps in a pedestrian movement or oncoming traffic unless prohibited by other controls Arrow Aspects Arrow aspects are used to control particular movements at traffic signal installations including U turn move ments as seen in Figure 5 1 Arrow aspect orientations to be used are shown in Figure 5 2 Figure 5 1 Signal aspects currently in use Note U turn and E aspects are not permitted in some jurisdictions Circular Arrow Pedestrian DON T WALK red only Buses Trams U turn Pedestrian WALK green only QM Emergency Bicycle vehicle 20 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 SIGNAL FACE LAYOUTS AND DISPLAY SEQUENCES Figure 5 2 Arrow aspect orientations NS Left turn 90 Left turn Straight through Right turn Right turn 90 Directional arrow displays supplement or cancel the intent of any circular displays with which they are associated Because the mask obscures the greater part of the lens the visual range is reduced For this reason straight through arrows used to control the faster movements should preferably not be used in red or yellow aspects and they should o
32. is the critical intersection in the signal coordination area Maximum green settings of 35 s for through and left turn movements and 14 s for the arrow controlled right turn movement 70 per cent of default values are selected as reasonably large values The resulting green times are 12 s for Phase C and 30 s each for Phases A and B The performance results under these timings are shown in Figure D 11 The largest degree of saturation is 0 760 average delay is 21 2 s for all vehicles and 37 4 s for all pedestrians If this intersection is not the critical intersection in the signal coordination area a longer cycle time may be imposed by the critical intersection Considering this the intersection performance with a cycle time of 120 s and the default maximum green settings is tested The resulting green times are 48 s for Phase A 44 s for Phase B and 10 s for Phase C This indicates generally satisfactory operation largest degree of saturation 0 900 average delay for all vehicles 24 9 s although average delay for all pedestrians was significantly higher 52 3 s Figure D 8 Average delay and level of service estimates for Design 2 with default maximum green settings Main Road North 40 5 11 4 A 3 7 z 612 3 a g of amp S E TS ls 2 e m a Lis ng o S ww 7 D m D o a S 41 6 51 7 55 0 Main Road South Main Road North LOS D LOS B LOSA fel 4 z 2 LOS F
33. line to provide a starting signal Figure 7 6 Figure 7 5 Signal face visibility templates a Visibility templates 240m Stop line Driver position at stopping distance Om Om lt 60km h gt 60km h 200 mm lanterns 300 mm lanterns b Typical application of visibility template for stopping sight distance of 100 m x Lantern not visible Lanterns visible Vehicle at sight distance Figure 7 6 Signal face location for channelised left turn control Figure 7 7 Signal face location for channelised right turn treatment seagull gt 6m AUSTROADS 55 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS ii Secondary and Tertiary Signal Faces Posts for these signal faces are located as shown in Figure 7 6 to provide starting and or manoeuvring functions The provision of both secondary and tertiary signal faces may not always be required Where there is a separate departure lane and secondary and tertiary signal faces are provided the posts should be placed either side of the separate departure lane to reduce the likelihood of driver error and incorrect manoeuvres see Figure 7 7 7 5 2 3 T Intersections i Primary Signal Faces Posts for primary signal faces are located as described in Section 7 5 2 7 i ii Secondary Signal Faces Posts for secondary signal faces at the head of the T are located as described in Section
34. this provides a combined leading and lagging right turn arrangement for a selected right turn movement unlike the lead lag right turn phasing Section 6 3 6 that applies to the right turns from opposing directions The right turn associated with the repeat phasing can be i either fully controlled using three aspect right turn arrows red yellow green in a six aspect signal face or 44 ii partially controlled using either three aspect right turn arrows red yellow green with red arrow drop out or two aspect right turn arrows yellow green in a five aspect signal face Where it is safe to do so the right turn movement subject to the repeat turn arrangement may be allowed to filter during the through phase partial control If filtering causes safety problems this right turn must be stopped using a red arrow display full control The right turn movement from the opposing direction should not be allowed to filter during the through phase in order to avoid the lagging right turn conflict discussed in Section 6 3 3 This phasing can be used for either full time or part time operation Its use will depend on the degree to which right turn traffic flow fluctuates at a site Repeat right turn phasing increases short lane capacities by using two short green intervals applicable to right turn bays It is also useful where there is insufficient storage on the immediate departure downstream side where traffic may b
35. to lanterns and demands from post mounted equipment to the controller Provide for underground installation of cable and access for maintenance Connect lanterns push buttons post mounted detectors etc to the multicore cable Determine display sequence and durations and provide switching of power to the signal lanterns Detect vehicles Installation of the sensor loop and connection to the detector For pedestrians to register demands and obtain acknowledgement AS 2144 AS 4113 AS 2339 AS 2339 AS 2339 AS 2979 Local AS 2276 Part 1 AS NZS 3000 Parts 1 amp 2 and local AS 2339 AS 2578 Part 1 and ocal AS 2703 AS NZS 2276 Part 2 amp AS 2276 Part 3 AS 2353 4 Domestic lamps not suitable 7 7 7 7 Agreement with local authorities usually required 12 12 Variation due to local installation practices 12 5 6 Variation due to level of complexity at intersections and alternative control algorithms used 8 Special purpose detectors are available 8 8 May also provide for visually handicapped Local traffic administration specifications AUSTROADS continued over page 15 TRAFFIC SIGNALS Table 4 1 Traffic signal components section numbers refer to this guide continued Component Purpose Specifications Section Comments Pedestrian sensors Detect pedestrians waiting to cross Local 8 the road or pedestrians who are on the crossing Traffic
36. 7 5 8 SYSTEM iud down demie demandera dede dus de be 4 1 1 Purpose ssssssestanensanscisuaianmausetanmimsns amas ba 4 1 2 SYSTEM PROCESS uc sues ee E de EO EA E eee Components bed bed SG y dure E une LAS nine und usd 4 2 1 Signal Lanters 23 os he oor ce ee aes ye eet gh code anus 4 2 2 Associated Equipment 4 2 3 Lantern Supports esc pesca ince FR EU URS dur Rte 4 2 4 Power Reticulation 4 2 5 Signal Controller 4 2 6 Traffic Detection 4 2 7 Roadway Components Component Selection Introduction 2 dette dan AS oe SHAME ASS eR os ASIN ne eke bake ek 5 1 1 Method of Controlling Traffic 5 1 2 Definitions Signal Face Elements 5 2 1 Signal Aspects 5 2 2 Colour of Aspects 5 2 3 Size of Aspects sara ag esu rrara graded rater 5 2 4 Types of Aspects 5 2 5 Target Boards Vehicle Signal Face Layouts 5 3 1 Basic Signal Face Layouts 5 3 2 Multi Column Signal Face L
37. 8 1 Introduction An important aspect of traffic responsive signal control systems is the detection of vehicle and pedestrian traffic demands in order to determine the signal displays required their initiation and duration For this purpose detectors are used to register the presence and or passage of vehicles and pedestrians Detectors can be grouped broadly as vehicle detectors push button pedestrian detectors and special det ectors Many types of detector exist including inductive loop push button microwave radar infrared sonic video image processing magnetic and pressure The most common detectors are the inductive loop det ectors for vehicles and the push button detectors for pedestrians For general information on detectors refer to FHWA 1996 8 1 1 Traffic Detection During a Signal Cycle Traffic can be detected at any time during the signal cycle In this respect there are two considerations a Initial detection Arriving traffic vehicle or pedestrian faced by a red signal registers an initial demand via a detection system that it requires a green signal b TZ Subsequent detection Vehicle traffic approaching on a green signal registers via the same detection system that it requires the green signal to continue even though the initial detection may have been made by another traffic movement in the same phase The type and location of detection systems used determines the parameters of the init
38. A detection system that employs stop line presence detection on a lane by lane basis is the most common method used in Australia This has been a result of the development of the SCATS wide area traffic control system Sims 1979 Sims and Dobinson 1979 Lowrie 1982 1990 1996 2001 Stop line loops require greater sensitivity as slow moving or stopped vehicles must be detected The location of the loop in relation to the stop line must ensure that the normal stopping position of the first vehicle is in the detection zone Figure 8 3 shows location and layout of 4 5 m and 11 m loops and loop configuration The lateral dimension of the loop should be derived from Table 8 1 Dean Macdonald and Morris 1981 for each situation as indicated in Figure 8 3 The 11 m detector may be used at locations where a shared or exclusive right turn lane permits filtering and a right turn phase is also provided see Figure 8 3 In practice the 11 m detector is split into two 4 5 m sections designated approach and departure loops that act together in some conditions and separately in others Longitudinal position of 11 0 m detector may vary depending upon intersection geometry 64 Detectors are not normally required in uncontrolled left turn slip lanes for signal control purposes but may be installed to allow traffic to be counted Figure 8 3 Configuration and layout for stop line loop a Layout of 4 5 m and 11 m loops D lane width
39. Ak elik 1981 Such methods calculate an optimum or practical cycle time and then calculate green times on the basis of equal degrees of saturation or specified practical degrees of saturation i e maximum acceptable target demand flow to capacity ratios Signal timing methods that estimate green times directly using actuated controller parameters and then calculate the resulting cycle time have been developed more recently Ak elik 1995a b c TRB 2000 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Table C 1 Summary of signal controller settings Setting Purpose Range Maximum Cycle Time Late Start Basic Minimum Green Increment for advance detectors Maximum Variable Initial Green for advance detectors Maximum Extension Green or Maximum Green Gap Early Cut Off Green Yellow Time All Red Time Presence Headway Space Waste Minimum Red Arrow Time Pedestrian Walk Time Pedestrian Clearance Time Pedestrian Delay Limit the total cycle time to reduce delays and queue lengths where applicable Allow the introduction of some signal groups to be delayed for a preset time Ensure that the green signal is displayed for a safe minimum time Add a small amount of time to the Basic Minimum Green Setting to provide extra green time for vehicles stored between the detector and the stop line Limit the initial green period determined by increments Contro
40. Figure 11 6 Supplementary plates excepting special vehicles from turn bans BICYCLES EXCEPTED AUTHORIZED VEHICLES EXCEPTED a geometry is sufficient to allow the U turn to be made in one manoeuvre by vehicles of the type likely to U turn b TZ there are no more than two opposing through lanes of traffic c there is adequate visibility of approaching vehicles d there would be no danger to pedestrians and e there is no left turn green arrow control in road to the right Where a fully controlled right turn phase is provided b and c above may not apply Supplementary plates such as LIGHT VEHICLES ONLY can be used with the U TURN PERMITTED sign in order to advise of site restrictions such as limited turning radii Figure 11 7 U TURN PERMITTED R2 15 sign TURN PERMITTED 11 3 6 U TURN PERMITTED Sign U turns at signalised intersections are prohibited in most Australian jurisdictions by legislation Where it is considered desirable and safe to relax this general rule the U TURN PERMITTED sign is used sign R2 15 shown in Figure 11 7 As a general rule the sign should only be used on intersection approaches with medians and preferably with right turn auxiliary lanes U turns should only be permitted where 78 11 3 7 TURN LEFT AT ANY TIME WITH CARE Sign The TURN LEFT AT ANY TIME WITH CARE sign should only be used at an intersection controlled by tr
41. OO CO OO er Mee 30 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 SIGNAL FACE LAYOUTS AND DISPLAY SEQUENCES Figure 5 20 Examples of display sequences to initiate an arrow controlled right turn movement During red circular display o OO OO e QO 9 During green circular display OD OO Ie OOO o Simultaneously with green circular display o OO OO ecc Od gt Displays where provided Figure 5 21 Examples of display sequences to terminate an arrow controlled right turn movement During red circular display 9 o Om 09 OO OO QOO MO During green circular display OO OUO D9 OOT O0O 0 OO oo O0 60 Simultaneously with green circular display OU OU 69 OO 09 00 eo OO LO Displays where provided AUSTROADS 31 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Figure 5 22 Display sequences for four aspect arrangement with single red right turn arrow aspect for the protection of pedestrians or special vehicles With pedestrian or special vehicle demand 69 Od Q O E Tr Without pedestrian or special vehicle demand 69 C QO e OOO OO
42. Section 5 show examples of four aspect and five aspect signal faces with a red left turn arrow Green left turn arrows may be used when there is no conflict with other vehicle or pedestrian movements Complementary left and right arrow controlled turns as shown in Figure 6 6 is the most common example of this See Figures 5 11 and 5 13 in Section 5 for examples of four aspect and five aspect signal faces with a green left turn arrow Figure 6 7 shows the use of complementary left and right arrow controlled turns at a T intersection where five aspect signal face layouts are used This example is used to demonstrate some issues regarding the use of green left turn arrows In this example there is no provision for pedestrians crossing the Eastern leg of the intersection Left turn green arrow from the East in Phase A and from the South in Phase B are not displayed because these arrows would be in conflict with the pedestrian movements A left turn green arrow should never be displayed in the same phase as a filter right turn from the opposing approach operates This is the other reason for not AUSTROADS displaying the left turn green arrow from the East approach during Phase A The introduction of the green left turn arrow is delayed by a few seconds at the start of Phase B in order to minimise the chances of conflicts between left turning vehicles from the East and filter right turning vehicles from the West clearing the intersectio
43. Shops Minimum green times for Phases A and B are 8 s as in Design 1 and minimum green time for Phase C is chosen as 6 s see Table C 2 Minimum pedestrian time requirements are not changed as a result of the changes to intersection geometry The additional start loss of 8 s is removed from the left turn movement from North It is retained for the right turn movement from North in Phase A but there is no additional start loss for this movement in Phase C For Phase C arrow controlled right turn maximum green setting 20 s and gap setting 2 0 s will be applicable default values Signal coordination data are unchanged D 4 2 Analysis Results for Design 2 With the default actuated signal settings an average cycle time of 138 s is estimated with green times of 20 s for Phase C and 50 s each for Phases A and B This is the maximum cycle time that results from all critical movements requiring maximum green times The intersection performance under this set of timings is not quite satisfactory as seen in Figure D 8 Although satisfactory performance is observed for the right turn AUSTROADS movement from North all pedestrian movements and the right turn movement from East are seen to experi ence long delays level of service E A sensitivity analysis indicates that shorter maximum green settings for all movements produce better results The results with the optimum maximum green settings of 23 s for through
44. Signal A signal which is used to enable the approaching driver to make a decision either to stop safely in front of the stop line or proceed into the intersection xxiii Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Stopping Sight Distance The sight distance which is necessary to enable a driver to stop safely in response to a red signal Sun Phantom The internal reflection of light from external sources especially the sun onto the lens of a signal lantern which makes it appear to be internally illuminated Symbolic Mask A mask used to create a symbol e g arrow pedestrian or bicycle or letter e g B or T to dedicate the aspect to a particular vehicle movement e g turning traffic or a special vehicle movement e g bus tram Also see Arrow Mask Synchronous Linking see Cableless Linking T Intersection An intersection where two roads meet whether or not at right angles and one of the roads ends Target Board The panel attached to a signal face to improve its visibility by reducing background luminance Tertiary Signal Face The signal face mounted on a post on the downstream side to the left of the approach Also see Primary Signal Face Secondary Signal Face Through Phasing Phasing that allows through and left turn movements and filter right turns from opposing approaches to operate in the same phase using the three aspect circular red yellow green signal faces Tidal Flow Schem
45. TIMINGS Table C 2 Typical signal controller settings used with 4 4 5 m stop line detectors in Australian practice values in seconds Vehicle Settings Arrow Through Controlled and Left Turn Right Turn Pedestrian Movements Movements Settings Late Start 2 5 0 6 Minimum Green 5 10 5 6 Maximum Extension Green 10 85 5 25 Gap 2 5 4 0 2 0 3 0 Headway 0 3 1 5 0 6 1 2 Waste 4 11 2 8 Early Cut Off Green 0 8 0 Yellow Time 3 0 5 0 3 0 6 0 All Red Time 1 0 3 0 1 0 3 0 Presence Time 0 3 0 5 Walk Time 5 16 Clearance Time 6 20 C 4 Vehicle Settings Actuated controller settings for vehicle movements are described in the following sections which are presented in the order they appear in Figure C 1 C 4 1 Late Start Setting The purpose of the Late Start Setting is to allow the introduction of some signal groups to be delayed at the start of a phase for a preset time Examples of the use of this setting are a To delay start of left turns 3 to 6 seconds depending on intersection geometry b To delay the start of a filtering right turn immediately following its control by a right turn green arrow display 5 seconds 127 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS C 4 2 Minimum Green Setting The minimum duration of the green signal minimum green time is determined considering the dynamic characteristics of the vehicles in the traffic stream A starting
46. Us 98 M 98 Lb ad iet boire detto a de 98 iaa Ra x md da dur du RD ADR T n 99 le 99 ne een 101 de E 102 sut De gate sde ge dati 102 JM 103 ee ee ce der da ded 104 TR 105 DUCTU 105 orgy Grane due dee 105 106 CT 106 Cr 106 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 CONTENTS Appendix A Human Factors A 1 General ican os bete that qe Dado e DO ee en ae hen eaten des A 2 Hawan BehaviGue 22 arae dressage ata dre den A3 VISION ER de de ere tu elias D nee A 3 1 Visual Sensitivity 25 2 5 kaise dd aie nt De Melia We eat abe de A 3 2 Visual Acuily erens epe PAE pes a as PAE ad es date PA tan A 3 3 Colour Perception sii sense Rene Rie uma RR Ree ke A 3 4 Photometric Requirements of Signals Appendix B Vehicular Traffic Factors B 1 SIC ME sare eae tae ba be eae dote Be ea ee Se eee bed ee B 2 Vehicle Deceleration and Acceleration Characteristics B 2 1 Deceleration Characteristics B 2 2 Acceleration Characteristics B 3 Basic Properties of Vehicular Traffic B 3 1 General 5c ta cect ni ata eater elas AE EN AN AT aeons B 3 2 Basic Parameters s np anne gen en dee Rep deer B 3 3 Flow Rate Densi
47. and left turn movements and 9 s for the arrow controlled right turn movement 45 per cent of default values is shown in Figure D 9 These settings give an average cycle time of 75 s with green times of 23 s for Phase A maximum 25 s for Phase B minimum due to the pedestrian movement and 9 s for Phase C Cycle time optimisation for coordinated signal oper ation purposes using reduced maximum green settings indicates that the intersection could operate satis factorily at a low cycle time of 80 s as seen in Figure D 10 The green times with this cycle time were 28 s for Phase A 25 s for Phase B and 9 s for Phase C The variable cycle time results indicate that the capacity is maximum at a cycle time of 85 seconds and signifi cant decreases in capacity are observed with increased cycle times The loss of capacity with increased cycle times for this example is due to the existence of filter 143 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Figure D 7 Signal phasing for Design 2 left turn vehicles from North approach give way to opposing through and right turn movements in Phases A and B Phase A Phase B Phase C In New Zealand opposed by right tums from West turns lane blockages by left turns waiting for pedes trians and filter right turns waiting for gaps and short lanes Given the above results a cycle time of 90 s is selected for coordinated signal operation on the basis that this
48. appropriate to the phasing as designed b TZ are the kerbside controls adequate for the required capacity of the site c are traffic flows actually as predicted or assumed d is traffic avoiding the signalised site and creating congestion elsewhere 92 e is equipment controller operating as designed f are signal phasings and timings Section 6 and Appendix C adequate to ensure that the yellow times in relation to vehicle stopping characteristics and times provided between phases to clear traffic from the controlled area are satisfactory ii traffic is not held unnecessarily at a red signal when adequate gaps exist in a running movement iii delays to vehicles and pedestrians on each approach are at satisfactory levels iv the numbers of vehicles left in a queue at the termination of the green period and the number of vehicles stopped more than once in each queue are at satisfactory levels v the occurrence of queue overflows from turning lanes blocking other movements is minimised vi if coordination exists good progressions are obtained as planned Section 13 does platooning by upstream signals or inter ference from downstream signals indicate a need for coordination Section 13 8 h are vehicle detector loops appropriately located to detect traffic as intended in both the passage and presence mode and is waiting traffic standing in the posit
49. arrow displays a flashing yellow arrow may be displayed after the red arrow where regulations permit This display indicates that a right turn may be made but the driver must give way to other vehicles and pedestrians that also have a signal to proceed d Part Time Full Control Full Control operates during certain hours of the day and Filter Only or Partial Control operates during other times of the day 6 3 1 Through Phasing with Filter Right Turns This phasing arrangement see Figures 6 1 and 6 2 allows the through and left turn movements and filter right turns from opposing approaches to operate in the same phase using three aspect circular red yellow green signal faces see Figure 5 3 in Section 5 AUSTROADS A filter right turn movement must give way to and find safe gaps in conflicting vehicle or pedestrian traffic before proceeding A phasing alternative that uses a green right turn arrow would be considered if a evaluation of the phasing indicates that the intersection performance is improved by providing a separate right turn phase Section 6 2 2 or b the filter right turn is considered unsafe due to crash risk factors Section 6 2 3 If a suitable phasing alternative that can cater for the right turn movements in an efficient and safe manner cannot be found consideration would be given to banning the right turns If only one right turn can be banned and the other right turn cannot filter effic
50. available for use determined as MTBF MTBF MTTR where MTBF Mean Time Between Failures and MTTR Mean Time To Repair Background Intensity The luminous intensity of the signal background Bandwidth The amount of green time common to all signals along the route in a coordinated system Green Band This can be determined as the time between the first and the last vehicle travelling at the design speed which can pass through a coordinated system of signals receiving a green signal on arrival at each stop line Bicycle Aspect A masked aspect that displays a bicycle symbol when the aspect is illuminated Also see Bicycle Signal Face Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Bicycle Signal Face A signal face for the control of bicycle movements that consists of two bicycle aspects red green or three bicycle aspects red yellow green Also see Bicycle Aspect Cableless Linking A mode of signal coordination in which linking is achieved by reference to an accurate clock in each signal controller The clocks are initially set to exactly the same time and maintained in synchronism by reference to the mains supply frequency The clock initiates the oper ation of a certain plan at a certain time of day and day of week according to a predetermined schedule Cable Linking see Local Interlinking Capacity The maximum sustainable flow rate at which vehicles or persons reasonably can be expected to trav
51. can be avoided by using the phasing alternatives given in Figure 6 1 or introducing right turn bans Section 11 covers the type of signs that can be used to ban right turn movements either full time or part time Figures 6 4 and 6 5 show two complete phasing arrangements for a cross intersection consisting of leading Figure 6 4 or lagging Figure 6 5 right turn phasing on one road and a through phase with filter right turns on the other road Thus the signal cycle consists of three phases in these cases With lagging right turn phasing a right turn trap situation can occur as discussed in Section 6 3 3 This can also occur with other phasing arrangements due to phase skipping Various measures to avoid right turn trap are discussed in Section 6 3 3 With all phasing options shown in Figure 6 1 except the split approach phasing provision of an exclusive right turn lane is recommended in order to a reduce the exposure to the rear end conflict between through and right turn vehicles b avoid lane blockage by vehicles waiting for gaps or stopped by a red display and AUSTROADS SIGNAL PHASING c isolate detection of right turn vehicles to prevent through vehicles unnecessarily calling the turn phase for leading right turn phasing A right turn bay is a practical solution for providing an exclusive right turn lane The length of the right turn bay should be determined during the evaluation process Section 6 2
52. caught within the system The disadvantage of this technique is that vehicles may encounter queues or red signals at those intersections where green time is limited Although the delay before 85 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS the through phase can be introduced may be short the smoothness of the progression is disrupted At some intersections this may cause all vehicles to stop and the back of queue to extend back towards the upstream intersection A compromise between the starting and finishing offset strategies is often possible e g synchronisation of the mid points of green periods as discussed in Akcelik 1981 but as a general rule it is more acceptable to coordinate starting offsets The simultaneous offset strategy is useful when inter sections are closely spaced and residual queues at the downstream intersection can cause blocking of the upstream intersection Rouphail and Ak elik 1992 The bandwidth is the amount of green time common to all signals along the route As shown in Figures 13 1 a to c the bandwidth can be determined as the maxi mum time interval which can be drawn on a time distance diagram between two parallel lines with a slope corresponding to the design progression speed enclosing the green periods of all the signals in the system Though simplistic the bandwidth gives an indication of the ability of the signals to pass a platoon of vehicles through the system
53. criteria exist in local guidelines they should be applied b All other relevant factors should be taken into account and proper engineering judgement should be exercised c The warrants alone should not be used to justify an installation If a site satisfies warrants this does not necessarily mean that signals are the best solution Alternative treatments such as the use of a roundabout should be considered to determine the optimum solution in terms of traffic performance measures levels of service and benefit cost ratios The reader should refer to other parts of the Guide to Traffic Engineering Practice series for information on other intersection types roundabouts sign controlled intersections interchanges 1 5 1 Signalised Intersection Warrants The terms major road and minor road are used below to indicate roads carrying the larger and smaller traffic demand volumes As a guide installation of signals may be considered at an intersection if one of the following warrants is met a Traffic demand volumes For each of four one hour periods of an average day the major road flow exceeds 600 veh h in both directions and the highest volume approach on the minor road exceeds 200 veh h OR Continuous traffic For each of four one hour periods of an average day the major road flow exceeds 900 veh h in both directions and the highest volume approach on the minor road exceeds 100 veh h and the speed of traffic on
54. drivers is related to reaction time braking characteristics of the vehicle distance from the stop line road gradient approach speed discomfort tolerance and behaviour of following traffic Since accident risk is highest during the transition from green to one movement phase to green to another movement phase the timing of this change interval is very important The braking capability of modern vehicles is high and in practice the discomfort incurred by rapid deceler ation is the main constraint in controlled stops Another important consideration is the perceived danger of a rear end collision with a following vehicle particularly a heavy vehicle which may not be prepared for the sudden deceleration These considerations are so important to many drivers that their first inclination is to attempt to cross the intersection during the yellow period AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 APPENDIX C SIGNAL TIMINGS Table C 3 Yellow Time values seconds determined using a 3 0 m s Vp 50 km h Vp 60 km h Vp 70 km h Vp 80 km h Grade t 10s t 15s t 10s t 15s t 10s t 15s t 10s t 15s 0 08 4 5 5 0 5 0 55 5 5 6 0 6 0 6 5 0 05 4 0 4 5 4 5 5 0 5 0 5 5 5 5 6 0 0 02 3 5 4 0 4 0 45 45 5 0 5 0 5 5 0 00 3 5 4 0 4 0 4 5 4 5 5 0 5 0 5 5 0 02 3 0 315 3 5 4 0 4 0 45 45 5 0 0 05 3 0 3 5 3 5 4 0 4 0 45 45 5 0 0 08 3 0 3 5 3 5 4 0 3 5 4 0 4 0 4 5 The yellow interval should only be long enough to enable
55. ensure that motorists are not kept waiting for an excessive period against a red signal see Section C 4 3 The waiting time for traffic facing a red display depends on a traffic flows on the subject approach as well as flows on other approaches b green time actuated controller settings c requirements of signal coordination on a conflicting phase The excessive time is related to the level of traffic activity at the intersection The behaviour of drivers is also related to feelings of perceived equity In other words drivers can be held against a red display in a minor side street for relatively long periods compared to the waiting time tolerated by drivers on a busy arterial road Subjective observations suggest that maximum waiting times against a red display range from 20 seconds under light traffic conditions to 120 seconds under heavy traffic conditions These values relate to the maximum delay experienced by an individual vehicle or pedestrian Average delay estimated by analytical methods is for all vehicles or pedestrians delayed AUSTROADS APPENDIX C SIGNAL TIMINGS and undelayed and therefore is shorter than maximum delay For example the worst level of service has been defined on the basis of average delay being above 70 to 80 seconds TRB 2000 RTA NSW 1993 Increased green time for a movement results in increased red times for competing movements which will then require longer green times
56. flashing yellow lights PREPARE TO STOP PREPARE TO STOP Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS downhill grade the warning device should be located approximately at the stopping sight distance from the stop line of the intersection on the approach side of the intersection see AS 1742 Part 14 The flashing yellow lights are started a fixed time in advance of the yellow interval when the main through traffic phase is terminating at the intersection using the early cut off period timer Appendix C 4 5 The flashing lights may be terminated at the start of the red display for the main through traffic phase In some jurisdictions the flashing lights are terminated at the start of the green display b TZ A traffic signal installation that is obscured from the view of approaching traffic such that there is a high risk of collision with the rear end of traffic queued at the signals the warning device should be located at not less than the stopping distance in advance of the probable end of the queue The yellow lights will need to flash beyond the start of the green display when the sight distance to the back of the queue for the through move ment is a problem The back of the queue will not begin to move until some seconds after the green signal is displayed This time can be calculated as the 95th percentile queue value in vehicles times the queue departure response time Akcelik Besley
57. for changes to improve the flow of traffic Examples of geometric improve ments include the provision of exclusive right turn lanes left turn slip lanes and line marking alterations to minimise lane changing caused by the lack of lane continuity along a road d Traffic Factors A complete inventory of traffic movements along a route to be coordinated is required This enables progression charts time distance diagrams and signal timing plans to be prepared Each individual intersection must be assessed first after which appropriate combinations of intersections may be assessed on a coordinated basis using a common cycle time e Traffic Equipment An inventory of existing equipment is necessary to identify constraints imposed by this equipment and to determine required changes 13 7 Coordination Requirements Affecting the Design of Signalised Intersections When undertaking the design of a set of traffic signals it is important to consider the effects that coordination will have on the design The major effects relate to the following factors a Traffic Signal Controller Selection A traffic signal coordination scheme will require the use of controllers that are compatible with the type of coordination adopted AUSTROADS b TZ c d e f COORDINATION OF TRAFFIC SIGNALS Detector Placement and Function In many cases the detection system required will be sp
58. for trains or trams For left turn traffic a green period must be assured when the circular green aspect is displayed alone SIGNAL FACE LAYOUTS AND DISPLAY SEQUENCES 5 5 3 Four Aspect Signal Face Layouts with Left Turn Arrow Aspects Single Left Turn Green Arrow Aspect A four aspect signal layout with single green arrow aspect Figure 5 13 may be used only when the left turn green arrow display is always terminated simul taneously with the circular green display i e when the circular yellow display is introduced Single Left Turn Red Arrow Aspect A four aspect signal layout with single red arrow aspect Figure 5 14 may be used only when its use is restricted to the sequence discussed in Section 5 7 4 Figure 5 25 This display is used infrequently It may be used to delay a filter left turn movement for the protection of pedestrians or special vehicles in which case the red arrow should be switched off at the earliest practicable time e g at the end of the Walk period Figure 5 11 Five aspect signal face layout with yellow and green left turn arrow aspects 000 Figure 5 13 Four aspect signal face layout with single left turn green arrow aspect o e or 6 00 Figure 5 12 Five aspect signal face layout with red and yellow left turn arrow aspects Cee Figure 5 14 Four aspect signal face layout with single left turn red arrow aspect
59. from the kerb may be necessary 7 5 4 Lantern Mounting Heights The mounting height is measured from pavement level to the top of the lantern body a Where possible all mounting heights should be 4 1 m Where the lantern is required to be visible within 20 m e g some starting or manoeuvring lanterns the mounting height may be reduced to 3 2 m Where reductions in mounting height are necessary to clear obstructions such as awnings a minimum clearance to the target board of 2 metres must be maintained b For pedestrian lanterns the mounting height should be 3 m Overhead lanterns should be mounted so that a clearance of 5 4 m to 5 8 m between the road surface and the bottom of the target boards is maintained c Excessive clearance may result in the lantern being located too far above the driver s line of sight d Clearance from the ground to any lantern target board shall be not less than 2 m 7 5 5 Clearances from Power Lines Minimum clearances from overhead power lines to any signal equipment are specified by the electricity authorities The required clearances vary depending on line voltage line insulation and local electricity auth ority practices therefore the local electricity authority should be consulted if equipment is to be located near power lines 7 5 6 Lantern Aiming a The visual range of each lantern is determined by its position photometric performance and its ori
60. green interval before gap change if the headways are too small for a gap change but too large for efficient traffic operation The efficiency is measured by difference of measured space times from the Headway Setting The difference is called a waste increment A waste timer operates throughout the running part of the phase but its operation is ignored until the start of the extension green interval i e until the end of the minimum green period or until a demand for another phase is received whichever comes later At the start of the extension green interval and at each detector actuation after that the headway timer is loaded with the Headway Setting When the detector actuation ceases i e at the end of the occupancy time the headway timer starts decrementing If the headway timer reaches zero before another actuation occurs the timer is said to have timed out The headway timer may time out many times during a phase The value of the waste timer at the start of the exten sion green interval equals the waste setting Whenever the headway timer is timed out the waste timer starts decrementing until a new detector actuation occurs The amount of decrement equals the waste incre ment When the waste timer reaches zero the waste timer is said to have timed out When this occurs before a gap change the phase will be terminated This is referred to as a waste change In addition to a gap change or waste change the phase can be
61. holdings price whole of life cost and standard isation of installation Some modifications of design may be required in order to achieve overall economic efficiency for the supply installation and maintenance of the system AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 5 Signal Face Layouts and Display Sequences 5 1 Introduction This section covers the design of signal face layouts and sequence of signal displays for different situations The advice is comprehensive and interrelated Particular advice should not be considered in isolation nor should variations be introduced without careful evaluation This section does not cover those special applications and facilities described in Section 15 5 1 1 Method of Controlling Traffic Traffic signals control approaching vehicles by displaying red yellow or green signals and pedestrians crossing the road by displaying red or green signals Traffic signals can also control special vehicles such as trams buses and emergency vehicles using white symbolic displays As with all traffic control devices it is important that the design of traffic signals follows defined conventions to ensure that a driver is not confronted with a display or a sequence of displays which is confusing Hesitancy potential for misinterpretation and accidents and unnecessary delays are reduced by design uniformity Basic design criteria aim to a give a logical and unambiguous presenta
62. in Sections 5 2 5 8 and 5 9 Signal face site requirements and positioning of signal equipment for pedestrian signals are dis cussed in Sections 7 4 4 and 7 5 2 4 Detection of cyclists is discussed in Section 8 5 3 Bicycles may be controlled by two aspect red and green bicycle signal faces or three aspect red yellow and green bicycle signal faces Section 5 9 1 The type of bicycle path exclusive shared etc is a factor in the selection of two aspect or three aspect signal faces It is recommended that at intersections a stop line for bicycles is placed 2 m downstream of the normal stop line so that left turning motor vehicle drivers in particular bus and truck drivers will be aware of bicycles waiting for a green signal If vehicles cannot turn left there is no need for this treatment A bicycle rider is required to dismount when crossing a road from a footpath bicycle path shared path or separated path whether traffic signals are installed or not However where bicycle lanterns are installed a bicycle rider facing a bicycle signal may negotiate the intersection or midblock location without dismounting 15 7 Roundabout Metering Signals Roundabout metering signals may be used where excessive queuing and delays are observed on one or more legs of a roundabout due to heavy circulating flow rates especially in the case of heavily directional origin destination movements In this case a dominant approach stream constit
63. lines Also see Exclusive Pedestrian Phase Secondary Signal Face The signal face mounted on a post on the downstream side to the right of the approach Also see Primary Signal Face Tertiary Signal Face Semi Actuated Control see Traffic Actuated Control xxii Sequence see Display Sequence Shared Lane A lane allocated for use by two or more movements e g shared through and right turn lane Also see Exclusive Lane Sight Distance The distance over which a road user needs to have unobstructed sight to respond to a visual cue or to safely avoid a conflict Sign see Traffic Sign Signal see Traffic Signal Signal Aspect see Aspect Signal Controller see Controller Signal Coordination see Coordination Signal Cycle see Cycle Signal Display see Display Signal Face A set of signal aspects in a common assembly generally in one or two columns placed together with a target board to improve signal visibility facing traffic from one direction Signal Group A signal group is a set of lanterns with common electrical switching such that the aspects illuminated in each lantern are always identical Signal Group Overlap see Overlapping Signal Group Signal Intensity The luminous intensity of the signal aspects Also see Luminance and Luminous Intensity Signal Lantern see Lantern Signal Linking see Coordination Signal Offset see Offset Signal Phase see Phase Signal Phasing Sequential arr
64. manufactured to the requirements of AS NZS 2276 Part 2 The sensor to loop distance should be minimised since long lengths of feeder cable may have adverse effects on detector sensor operation The loop cable should be manufactured to the requirements of AS 2276 Part 3 12 5 Data Link Cables Data link cables are either leased from telecommun ication authorities or manufactured and installed to their requirements The desired data transfer rate deter mines the cable types that are required Aspects of Section 12 2 are also pertinent 82 12 6 Cable Connection Design The cable connection design determines the size length and routing of cables The circuits connecting lanterns push buttons and wait indicators to the controller may be optimised to produce the most economic solution The number of cores in the multicore cable is chosen to provide sufficient circuits for each colour of each signal group push button and pedestrian wait indicator The cores are connected from the post mounted ter minal block on each post to the controller terminals The cable connection chart documents the cable connection design Details of the connection of indi vidual cable cores to the appropriate terminals in the controller and on each terminal block at each post are shown A typical example is illustrated in Appendix C AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 13 Coordination of Traffic Signals 13 1 Introduction Co
65. may be applied a as a permanent arrangement at a single lane bridge or other roadway constriction that is too narrow for two way traffic e g repair works that will continue for a long period of time and where the combination of the length of single lane section traffic volume and inter visibility between approaches does not permit the safe use of GIVE WAY or STOP sign control or uncontrolled operation or b TZ as a temporary arrangement using portable traffic signals or temporary fixed traffic signals at roadworks or bridgeworks where the conditions in a above apply For permanent and temporary fixed traffic signals signal faces comprise a single column with three circle aspects A primary signal face must be installed on each approach Both secondary and tertiary signal faces are recommended for each approach in case of lamp failure The minimum requirement is two signal faces for each approach The secondary and tertiary signal faces are installed 6 to 10 m beyond the primary signal face A regulatory sign STOP HERE ON RED SIGNAL Section 11 3 2 is erected adjacent to the stop line For portable signals see Section 15 11 2 The general treatment for single lane operation is to use two phases where one phase controls each direction of traffic This requires very long intergreen times to allow one movement to clear the conflict area before the other movement can be started This causes long delays that could lead to
66. measures ITE Australian Section 1985 Taylor 1996 Passive priority measures include reduced cycle time green time allocation and basic phasing design with bias to favour bus and tram movements repetition of bus and tram movement phases in one signal cycle and signal coordination with special consideration for bus and tram movements Active public transport priority techniques at traffic signals include a phase extension i e holding the green display to allow the bus or tram to clear the intersection b TZ phase early start i e early display of the green signal when a bus or tram facing a red signal is detected c provision of special tram phases at complex intersections with multiple phases d phase suppression i e skipping a non tram phase in some limited circumstances in order to service a tram or bus phase more quickly A technique called flexible window stretching that combines phase extension and early start methods has been used for tram priority within the SCATS control system ITE Australian Section 1985 McGinley 1983 This technique has the ability to provide priority at any point in the signal cycle and transfer time between phase extension and early start phases However at sites with significant pedestrian activity associated with the side road phase the amount of time that can be taken away from the side road phase is significantly reduced A single frequency transponder
67. o ose xe cars we ase TT uL 12 1 G n ral nuda a5 a een oo ba ew ek ow Da ees Oba ewe ane ial Saree ner mate 12 2 Meallan PTT 12 3 CAI ES oi oo ee de tedden eine E E EE bole kiae ose EE EEEE 12 4 Vehicle Loop Detector Cables 12 5 Data Link Cables iai ctt ee eee 12 6 Cable Connection Design 13 Coordination of Traffic Signals 13 1 13 2 13 3 13 4 13 6 13 7 13 8 AUSTROADS Introduction Principles of Coordination 13 2 1 Fundamentals of Si 13 2 2 Offset Strategies The Case for Coordination Types of Coordination 13 4 1 Local Interlinking gnal Coordination 13 4 2 Synchronous Linking 13 43 Wide Area Control Coordination Methods 13 5 1 Fixed Time Plan Se 13 5 2 Traffic Responsive Systems su ics eae ia eee eA EG AIR ea ee RR lection System Plan Selection System 13 5 3 Fully Adaptive System Design Factors Coordination Requirements Affecting the Design of Signalised Intersections Coordination Timing Criteria 75 75 75 75 75 75 75 75 75 76 76 77 78 78 79 79 79 80 80 80 80 81 81 81 81 82 82 82 83 83 83 83 85 86 86 86 87 87 88 88 88 88 88 89 90 xi A
68. of a single column of red and yellow aspects and a white special vehicle aspect B for Buses T for Trams or E for Emergency vehicles that provides control of special vehicle movements Figure 5 1 In some cases it may be necessary for special purpose aspects to be mounted and aimed separately from vehicle or pedestrian displays Single aspect white aspects are also used to control special vehicle movements 5 10 2 Special Vehicle Sequence The sequence for special vehicle displays is Red to White to Yellow to Red Where white special vehicle lanterns are displayed as single aspect units the sequence is Off to White to Off AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 A single white aspect does not fully control a special vehicle movement i e its absence does not compel a special vehicle to stop 5 11 Signal Start up and Failure Displays 5 11 1 Signal Display on Failure When the intersection cannot be controlled with the normal vehicle displays due to equipment malfunction or maintenance activities the display recommended is flashing yellow displays at a rate of 1 Hertz with equal On and Off times Flashing yellow displays are safer than blacked out displays Blanks Davies and Hulscher 1976 have measured the public acceptability of the incidence of various types of signal display faults Davies Hulscher and Syme 1978 showed that the public regard blacked out signals as being unacceptably hazardous
69. of vehicles Lane Control Signal A signal face mounted above a lane in an overhead lane control scheme which is used to control the direction of vehicle flow in the lane during a particular time Lane Group A set of lanes allocated to a particular movement in exclusive lanes or to several movements with common shared lanes Lantern A signal assembly of optical components one or more aspects together with the means of connecting them to power supply and facilities for mounting the com plete assembly Also see Aspect Late Start The phase interval used at the start of a phase for delaying the start of some movements Leading Right Turn An arrow controlled right turn movement that is started and terminated in the phase that immediately precedes the phase in which the opposing through movement runs AUSTROADS GLOSSARY Lead Lag Right Turn Phasing A phase sequence that commences with a fully cont rolled leading right turn from one approach followed by a through phase and terminates with a lagging right turn from the opposing approach Level of Service An index of the operational performance of traffic on a given traffic lane carriageway road or intersection based on service measures such as speed travel time delay and degree of saturation during a given flow period Limit Line see Give Way Line Stop Line Linking see Coordination Local Interlinking A signal coordination system comprising a small
70. off Their use should be mini mised because louvres reduce the efficiency of the optical system and they produce reflected images that are visible under low ambient lighting AUSTROADS LOCATION OF SIGNAL EQUIPTMENT a Louvres should not be used in association with symbolic aspects b Horizontal louvres are used to i minimise sun phantom illuminations where visors have proved ineffective ii restrict the signal display coverage along the approach c Vertical louvres are used to i produce the required signal display where the cut off provided by visors is inadequate typically at skewed intersections ii restrict the visibility of the signal display to a certain lane or lanes of the approach iii shield the lantern from the view of train drivers or other persons in the vicinity of an intersection when it is desired that such persons should not be able to see the lantern Table 7 4 Cut off angles for visors Angle for Lantern Visor Type Total Cut Off Size as per Length of Signal mm AS 2144 mm Indication 200 Open Type A 200 No restriction 200 Closed Type B 200 90 200 Closed Type B 300 67 200 Cutaway Type C 300 Open side see 7 6 b 32 on Closed side 300 Open Type A 300 No restriction 300 Closed Type B 300 90 300 Closed Type B 400 74 300 Cutaway Type C 400 Open side see 7 6 b 37 on Closed side 59 Accessed by AR M VICROADS on 02 Jun 2005 8 Traffic Detection
71. red railway display should be provided as part of the control AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 15 3 4 Conflicting Railway and Road Signals Special precautions may need to be taken to shield any green roadway display from traffic approaching or stopped by a flashing red railway display Similarly roadway displays should be shielded from the view of train drivers 15 4 Emergency Vehicle Facilities 15 4 1 Facilities Close to a Signalised Intersection When a fire or ambulance station is close to a signalised intersection special precautions shall be taken to ensure that stationary vehicles do not block emergency service vehicles that are trying to exit in an emergency The measures for this purpose include a relocating the stop line further from the intersection and b adding a special emergency service phase to the intersection signals Relocating the stop line could be appropriate where the exit from the emergency service facility is at the intersection If the resulting position of the stop line is SPECIAL APPLICATIONS AND FACILITIES unnatural from the motorist s point of view extra facilities such as a wider 600 mm stop line and the STOP HERE ON RED SIGNAL sign Section 17 3 2 may be necessary It may also be appropriate to provide signs and pavement markings to warn motorists not to queue across the driveway Section 10 5 When the exit from the emergency service facility is too far f
72. sharp increase in space time at low speeds and therefore leading to a double valued speed space time relationship 119 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Figure B 5 The relationship between space time and speed as a function of the detection zone length using average parameter values for through traffic lanes surveyed in Melbourne and Sydney Average Thru All sites Space time t s Detection zone length Lp m vf 69 0 Speed v km h 50 60 70 80 It was found that the optimum detection zone length is strongly related to jam gap length Lj Using a limiting speed value of v 10 km h the following expression can be used to determine the optimum loop length as a simple method L 19987 B 3 19 Jam gap length characteristics vary for individual sites and therefore should be measured wherever possible Since it is easier to measure the jam spacing the jam gap length can be calculated with the help of Equation B 3 14 assuming an average vehicle length Using the average jam gap length values given in Table B 1 this expression gives optimum loop length values of 4 5 m for through traffic lanes and 3 7 m for right turn lanes While these are consistent with the stop line presence detector loop lengths used in Australia analyses of individual sites indicated that optimum loop lengths in the range 4 0 to 4 8 m for through traffic lanes and 3 0 to 3 8 m fo
73. signal timings and give a complete worked example A glossary of terms is included 158 AUSTROADS AUSTROADS PART 7 GUIDE TO TRAFFIC ENGINEERING PRACTICE SERIES AP G11 7 03 ISBN 0 85588 622 6 HB 191 2003 LAN 7A 1 7 AUSTROADS z SF Accessed by AR M VICROADS on 02 Jun 2005
74. signalised intersection requires considerations of safety adequate capacity efficient traffic operation minimum delay queue length and stops for the intersection as a whole as well as equity in levels of service provided for different movements major road vs minor road and vehicles vs pedestrians and priority to public transport vehicles This appendix discusses general aspects of signal timing methods Section C 2 describes actuated signal con troller operation Section C 3 and presents guidelines for determining appropriate values of controller settings Sections C 4 to C 6 Certain timing constraints are imposed on signal oper ation for safety reasons Safety requirements constrain the minimum green time minimum red arrow display time minimum pedestrian walk and clearance times and intergreen time Maximum tolerable delay needs to be considered due to its implications on safe oper ation of signals Section C 2 2 Table C 1 presents a summary of signal controller settings their purposes and recommended values C 2 Signal Timing Methods C 2 1 Green Times and Cycle Time Signal timing methods are used to determine appropriate green times and cycle time Although most modern signals operate in actuated control mode historically signal timing calculation methods for fixed time signals have been applied to actuated signals as well mainly to determine the maximum green time Webster and Cobbe 1966 Miller 1968
75. state of interaction between influences such as noise Figure A 2 Conceptual model of the human decision making process Rate of output decision rate Information processed Error or information missed or shed Actual performance vemm Presentation rate task demand 108 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 sleeplessness intoxication incentive and time of day A rise in arousal yields a rise in performance only up to a certain optimal level but any increase in arousal beyond this optimal level will produce a drop in performance Such limitations in road user performance should be taken into account in the design of traffic signals The safe and efficient movement of vehicles and pedestrians can be assisted by requiring road users to make simple decisions one at a time with adequate time between decisions and with sufficient advance warning This is helped by measures such as a providing the minimum number of signal faces for safe traffic control b ensuring consistency and uniformity of signal installation and operation c ensuring sight to potential traffic conflicts is not obstructed e g for a filter right turn or a left turn from a slip lane d TZ ensuring signs and pavement markings are adequate for special provisions e g turn bans left turn on red exclusive pedestrian phase e providing adequate advance warning of traffic signals lane disc
76. storage space approach short lanes can be limited especially when long cycle times are used Akcelik 1981 Similarly gains from downstream short lanes can be limited due to underutilisation of the lane on the approach side Through lanes across an intersection should be aligned to achieve a clear definition of vehicle paths When it is desired to store vehicles in separate turning lanes adjacent to through traffic lanes it is important to ensure that adequate storage length is provided Where adequate storage length cannot be provided the signal phasing and time settings may be modified The design of appropriate storage length is based on a selected percentile queue length e g 95th percentile value queue length exceeded in 5 per cent of signal cycles An important aspect of the design of intersection geo metry is the decision about the use of exclusive lanes allocated for use by one movement and shared lanes allocated for use by several movements e g shared through and right turn lane This should aim to achieve balanced lane use by existing demand volumes 3 2 2 Right Turn Lanes Where through and right turn vehicles share a lane the following may occur a hazardous situations created by a stationary right turn vehicle in the lane due to restricted sight distance b blocking a through lane reducing capacity increasing delays and queue lengths and c an inefficient use of any right turn traffic phase T
77. the event of signal failure To reduce the number of posts at a signalised inter section it may be possible to mount small signs on signal posts provided the posts are suitably located and the signs do not interfere with signal operation or maintenance 11 2 2 Periodic Signs It is often necessary to prohibit certain movements or classes of vehicles in order to maximise intersection throughput in peak traffic demand periods At signalised intersections this may be achieved by a The use of Regulatory Signs together with supplementary plates showing the times of operation see Figure 11 5 in Section 11 3 5 This type of prohibition applies regardless of traffic variations e g 4 00 pm 6 00 pm Mon Fri b The use of switchable signs that are displayed only when the restriction applies The display may be achieved by internal illumination Section 11 2 3 or by mechanical rotation or shutters The restriction can be imposed as required in association with an area traffic control plan and in combination with a suitable signal display The installation and maintenance costs are higher than fixed signs Operational safety in the breakdown mode should be ensured 11 2 3 Illuminated Signs Internally illuminated fibre optic and LED signs are used at signalised intersections This sign can be an illuminated white legend e g NO RIGHT TURN on a black background or a symbolic sign e g a symbolic no right turn sign se
78. the intersection or midblock device it is controlling including specifications of which signal groups run in each phase the sequence of phases detector functions detector alarm conditions and default time settings Controller Programming The task of configuring a controller to the specific requirements of a particular site Also called Adaptive Engineering Controller Settings User defined control parameters within a traffic cont roller that determine signal timings together with current traffic demands in the case of traffic actuated controller Coordination The operation of a traffic signal system where the control of individual installations is interrelated by means of a Wide Area Control System Local Interlinking or Cableless Linking Cowl see Visor Critical Intersection The intersection in a coordinated signal system that operates with the highest overall degree of saturation during a given period Critical Lane The lane in a lane group or approach that has the highest degree of saturation and places the highest demand on green time Critical Movements The set of movements that determine the capacity and timing requirements of a signalised intersection Crosswalk Lines Continuous or broken lines marked transversely across the road to define the limits of a signalised crossing Also see Marked Foot Crossing Signalised Crossing Cycle A complete sequence of signal phases AUSTROADS Accessed by AR
79. the metered approach traffic if detectors are used on that approach A minimum of two signal faces one primary and one tertiary shall be installed A regulatory sign STOP HERE ON RED SIGNAL Section 11 3 2 shall be fixed to any signal post erected adjacent to the stop line as drivers do not expect to stop at the advance stop line location Stop lines shall be located not less than 3 m in advance of the approach holding line but preferably should be positioned approximately 20 m from the holding line Queue detector setback distance on the controlling approach is usually in the range 50 m to 120 m Various site specific methods may also be used to meter traffic e g using an existing upstream midblock signalised crossing on the metered approach In some cases it may be necessary to supplement the traffic signals with explanatory fixed or variable message signposting Where sight restrictions exist advance warning signals should be considered Section 15 2 Figure 15 3 Roundabout metering signals Detector setback Controlling approach Stop line setback Metered approach 100 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 15 8 Ramp Metering Signals Ramp metering systems control the flow of traffic entering a freeway via access ramps in order to prevent the breakdown of flow on the freeway and hence preserve its ultimate capacity and minimise delay and travel time Lowrie 1996a Ramp
80. time between the commencement of a stimulus e g change in signal condition and the taking of appropriate action e g application of vehicle brakes Phase That part of a signal cycle during which one or more movements receive right of way subject to resolution of any vehicle or pedestrian conflicts by priority rules A phase is identified by at least one movement gaining right of way at the start of it and at least one movement losing right of way at the end of it Phase Sequence The order of phases in a signal cycle Also see Display Sequence Signal Phasing Phase Split Duration of each phase Green Time and Intergreen Time within a signal cycle It is normally expressed as a percentage of cycle length Phasing see Signal Phasing Plan see Timing Plan AUSTROADS GLOSSARY Platoon A group of vehicles or pedestrians travelling together because of signal control geometric conditions or other factors Post Vertical tubular support for traffic signal lanterns and associated signs Presence Detector A detector that produces a continuous output while a moving or stationary vehicle is present within the detection zone Primary Signal Face The signal face mounted on a post at or near the left of the stop line of the approach Also see Dual Primary Signal Face Secondary Signal Face Tertiary Signal Face Priority Rule A traffic regulation which assigns priority to one stream of traffic Also see Conflicting Mo
81. used for the mounting of lanterns provided that agreement to do so can be obtained from the utility authority A minimum 1 m clearance should be provided from lanterns to other separate street furniture items Where possible streetlights and lanterns should be located on one common post or structure under a joint use arrangement with the local electricity authority The use of common posts for mounting guide signs and signal hardware is encouraged see Section 11 2 1 7 6 Visors Visors are used to modify the angular visual coverage of the lantern e g to hide the lantern from the view of drivers on other approaches and or to shield the lantern optical system from incident light that may produce sun phantom illumination see Figure 4 2 in Section 4 a Table 7 4 details the angle at which the signal is totally cut off from view for various visors b Cutaway visors are used to provide additional visibility on the cutaway side and standard cut off on the other side c Where no restriction of angular coverage is required an open visor should be used to shield the lantern from incident light d Closed visors are normally used on secondary and tertiary lanterns The shorter closed visor should be used unless additional angular cut off is essential The longer visors are also more difficult to protect from damage 7 7 Louvres Louvres are used when visors are unable to provide the necessary visual cut
82. without stopping It is necessary to construct different signal coordination plans in order to cater for differing traffic flow demand patterns i e am peak pm peak and off peak Each plan consists of the system cycle time green splits and offsets Section 13 2 1 The plans are selected either by time of day or by using a traffic responsive method or calculated on line by adaptive control algorithms Section 13 5 The basic offset strategies discussed above do not involve modelling of queues that are likely to exist at downstream signals as a result of the trailing end of the main road platoon being stopped in the previous signal cycle and vehicles turning from the side roads of the upstream intersection These queues interfere with the progression of platoons Furthermore the calculation of signal coordination plans that yield opti mum progressions is not an easy task especially for closed loop network formations i e two way progress ions on an arterial road and grid networks For this reason various computer methods have been devel oped for determining optimum signal offset plans Signal timing plans should be verified by on site obser vations and fine tuned accordingly See Section 13 8 for further discussion 86 13 3 The Case for Coordination An isolated intersection is one in which vehicle arrivals at each approach are not significantly affected by other intersections This situation can be managed by traffic ac
83. xk Y dj d2 distances from loop wires to lane edge ab Ge ewe dees Call only 45 d4 0 5 d3 2 0 Stop line N 11 0 A rectangular type loop can also be used Dividing line 2 wires 2 wires 2 wires The two loop sections are wired in series and connected to one sensor AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 Table 8 1 Lateral dimensions of symmetripole loops Spacing from Each Outer Wire of Loop to Lane Edge When Adjoining Lane Width General Median Strip Kerb Side m m m m 2 5 3 0 0 74 0 55 0 83 3 0 3 5 0 73 0 54 0 82 3 5 4 0 0 72 0 53 0 81 4 0 4 5 0 71 0 52 0 80 4 5 5 0 0 70 0 51 0 79 5 0 5 5 0 69 0 50 0 78 d and d in Figure 8 3 8 3 4 2 Advance Detection In Australia detectors located in advance of the stop line for the purpose of detecting moving vehicles are usually used on safety grounds i e used at sites where approach speed is high and particularly when there is a large proportion of heavy vehicles For this purpose they should be located to suit the stopping distance required for the 85th percentile approach speed where possible Advance detector loops are used in addition to the normal stop line detectors They can be set in presence or passage mode Advance detector loops are also used without stop line detectors as shown in Figure 8 4 Figure 8 4 Advance loop lt gt Distance from stop line TRAFFIC DETECTION
84. 1 2003 Accessed by AR M VICROADS on 02 Jun 2005 Foreword Austroads works towards uniformity of practice in respect of design construction and user aspects of roads and bridges and with this purpose in view publishes guides and general procedures Traffic Engineering Practice first published in 1965 is a practical guide to traffic engineering for highway and transport engineers in Road Authorities Local Govern ment and engineering consultants and as a reference for engineering students The guide consists of 15 parts as shown below Part 1 Traffic Flow 2 Roadway Capacity Traffic Studies Treatment of Road Crashes Intersections at Grade 3 4 5 6 Roundabouts 7 Traffic Signals 8 Traffic Control Devices 9 Arterial Road Traffic Management 10 Local Area Traffic Management 11 Parking 12 Roadway Lighting 13 Pedestrians 14 Bicycles 15 Motorcycle Safety The information contained in the various parts is intended to be used as a guide to good practice Discretion and judgement should be exercised in the light of many factors which may influence the choice of traffic engineering treatment in any given situation These guidelines make reference where relevant to current Australian Standards and are intended to supple ment and otherwise assist in their interpretation and application This is the third edition of Part 7 Traffic Signals Part 7 focuses on technical aspects of designing safe and efficient traf
85. 2 An exclusive right turn lane is essential for operation of diamond overlap phasing and is recommended in the case of fully controlled right turns Where a right turn is banned part time using a switchable electronic sign the switching of the sign should be coordinated with the signal displays in order to obtain a safe transition If the right turn movement is arrow controlled the sign should preferably switch on at the same time as the arrows change from a yellow display to a red display or red arrow drop out The phasing alternatives shown in Figure 6 1 can be achieved through the following types of right turn control at traffic signals a Filter Only No right turn arrows i e three circular aspects red yellow green only Green circle alone indicates that right turning drivers can filter through gaps in the opposing vehicle and pedestrian traffic Normally right turning vehicles give way to through and left turning vehicles from the opposing direction However right turning vehicles have priority over left turning vehicles using a slip lane b TZ Full Control Three aspect red yellow green right turn arrows on a six aspect signal face The green arrow indicates that the vehicle can turn unopposed with no opposing vehicle or pedestrian traffic and the red arrow indicates that the vehicle is not permitted to turn Filter right turns are not permitted at any time during the cycle c Partial Contro
86. 2 m s default Clearance distances of 14 m for North South movements and 26 m for East West movements including both carriageways and the median width as applicable are used Minimum time requirements for pedestrians are determined as the sum of Walk and Clearance 1 time see Figure C 2 Clearance 1 time is deter mined as the total clearance time less Clearance 2 time overlap with the intergreen time The aaSIDRA default value of 2 s Clearance 2 time is used The resulting pedestrian minimum green times Walk plus Clearance 1 are 16 s for North South movements and 26 s for East West movements The aaSIDRA method for actuated signals may use a smaller average minimum pedestrian time requirement so as to allow for signal cycles with no pedestrian demand This is likely to come into effect with low pedestrian volumes on the crossings in front of the East and West approaches Default values of actuated signal settings maximum green and gap settings will be used Effective detection zone length is 4 5 m for all lanes Due to the phasing arrangement without any arrow controlled right turns in Design 1 maximum green setting 50 s and gap setting 2 5 s will be used for all movements 8 h Actuated coordinated signals are assumed Arrival types of 5 Highly favourable progression quality for the through movement on the North approach and 4 Favourable progression quality for the through movement
87. 3 3 152 PEDESTRIAN TIME SETTINGS 1 DELAY Pedestrian delay setting is not used 2 WALK Walk time is 6 seconds for each pedestrian movement 3 CLEARANCE 1 Clearance 1 time see Figure C 2 is 10 s for P1 and P2 and 20 s for P3 These are based on the use of clearance distances of 14 m for P1 and P2 and 26 m for P3 see Section D 3 1 4 CLEARANCE 2 Clearance 2 time is 2 s for all pedestrian movements 2 s overlap with yellow time of the terminating intergreen i e with Phase A intergreen for P1 and P2 with Phase B intergreen for P3 AUTO SWITCH This is not applicable since actuated pedestrian move ments are used this is used for introducing the pedes trian feature automatically with the associated phase PEDESTRIAN PHASES This indicates the phase s associated with each pedes trian movement Other Time Settings Further time settings not shown in Figure D 16 are recorded on the Timing Card These include special movement time settings presence time settings signal coordination features and so on In this example there are no special movements and the only presence timed detector is the 11 C A1 detector 11 m long where a presence time of 2 s is appropriate A phase operates as the recall phase to facilitate signal coordination along North South approach AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 References AKCELIK R 1981 Traffic Signals Capacity and Timing Anal
88. 4 0 w o t Occupancytime N o t Occupancy time to and Space time ts s 1 0 ton 076 0 0 40 50 60 70 Speed v km h As seen in Figure B 5 the uniqueness of space time and the speed below which it becomes zero depends critically on the effective detection zone length Ly For low values of L each space time measurement corresponds to two values of speed and this is not useful for traffic control for the same reasons as stated for the passage detector For large values of Lo each space time measurement provides a unique value of speed but if L is excessive the lower range of speed is restricted because of zero space time values at relatively high speeds A discussion of optimum detection zone length based on data collected in Sydney and Melbourne summarised AUSTROADS in Table B 1 can be found in Ak elik Besley and Roper 1999 The optimum length for a detector loop is one that is as short as possible but not so short as to result in a double valued space time relationship To determine the optimum loop length a limiting low speed value vj that gives zero space time needs to be chosen The limiting speed needs to be selected conservatively since if it is too low the loop length may be too short under adverse driving conditions e g wet weather or darkness This is because the gap lengths may increase and speeds decrease under adverse con ditions resulting in a
89. 49 3 4 0 17 4 4 33 4T 42 48 0 443 987 0 449 3 4 0 17 4 5 33 5R 42 12 27 9 230 340 0 676 28 9 0 83 7 1 47 80 West Side Street West 1LT 65 25 178 282 0 630 34 1 0 74 7 8 58 50 2 TR 67 23 0 0 244 388 0 630 36 3 0 79 11 6 83 S Figure D 12 Percentage spare capacity vs flow scale for Design 2 with reduced maximum green settings 20 5 10 Practical spare capacity 15 4 20 T T T T T T T T 100 104 108 112 116 120 124 128 132 136 140 Flowscale 146 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 D 5 Implementation of Proposed Design D 5 1 Provision of Signal Hardware and Location Following the signal timing and performance analyses in the previous sections the intersection geometry and phasing design can be finalised and the necessary signal hardware such as signal faces posts mast arms controller detector etc as well as the line markings and signposting may be included on the base plan of Design 2 For detailed information see Section 7 for the use and location of this equipment Section 8 for the basic logic and installation of detector Section 70 for various types of pavement marking and Section 11 for signposting Figure D 13 shows the line marking signal face loc ations and provision of some accessories The following discussions are based on this figure APPENDIX D WORKED EXAMPLE a Signal Faces Since the movements on the East South a
90. 7 0 7 0 6 16 HEADWAY 2 5 0 7 0 7 0 6 17 HEADWAY 3 5 5 18 HEADWAY 4 5 gt 19 WASTE 1 50 40 4 0 2 0 20 WASTE 2 50 40 4 0 2 0 21 WASTE 3 50 gt 22 WASTE 4 50 gt SPECIAL ALL RED SEQUENCES PROHIBITED SEQUENCES AC 150 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 APPENDIX D WORKED EXAMPLE Controller Time Settings continued Figure D 16 Phase and pedestrian time settings recorded in a typical Timing Card for Design 2 continued Pedestrian Time Settings Time Pedestrian Setting P1 P2 P3 P4 P5 P6 P7 P8 No Description Limit 1 2 3 4 5 6 7 8 1 DELAY 20 2 WALK 40 6 6 6 3 CLEARANCE 1 40 10 10 20 4 CLEARANCE 2 10 2 2 2 AUTO SWITCH OFF OFF OFF PEDESTRIAN PHASES C A A B D 5 3 3 Timing Card 4 INCREMENT A Timing Card is used to record controller settings Part This is not applicable since there are no passage of a typical Timing Card completed for Design 2 is detectors shown in Figure D 16 Values given in this figure are 5 MAXIMUM INITIAL GREEN based on those used in the aaSIDRA analysis for 0 4 This is not applicable since there are no passage Design 2 where applicable Dashes have been used d ee for those time settings that are not applicable These etectors see Section CES should not be confused with zeros that if used 6 MAXIMUM EXTENSION GREEN would produce zero time settings These are calculated as the maximum green The entries in the
91. 7 5 2 1 ii but posts for secondary signal faces for the stem of the T are located to the right of the projection of the centre line but closer to the line of sight of the approaching motorist Figures 7 2 a and 7 8 a The preferred location of the signalised crossing is to the left of the stem as shown in Figure 7 8 b Figure 7 8 c shows the relocation of posts for secondary and tertiary signal faces to allow a common post to be used with a pedestrian signal face iii Tertiary Signal Faces Posts for tertiary signal faces are located generally as described in Section 7 5 2 1 iii except that some adjustment is normally made to allow the common post to be shared with the secondary signal face for the stem of the T 7 5 2 4 Midblock Signalised Crossings Figures 7 2 b and 7 9 i Primary Signal Faces Posts for these signal faces are located as described in Section 7 5 2 1 i ii Secondary Signal Faces For undivided carriage ways these signal faces are mounted with the primary signal face of the opposite approach on a common post For divided carriageways secondary signal faces are mounted with the pedestrian signal face on a common post located on the projection of the crosswalk line iii Tertiary Signal Faces For both divided and undivided carriageways these signal faces are mounted with the pedestrian signal face on a 56 common post located on the projection of the departure side crosswalk line iv O
92. CROADS on 02 Jun 2005 TRAFFIC SIGNALS The relationships among flow rate veh h density veh km and occupancy ratios percentage values are summarised below q 3600 h 1000v L B 3 9 B 3 10 B 3 11 k 1000 L q v q vk O 100t h 100 L L L B 3 12a for presence detection and subject to O s 100 O 100t h 100L L B 3 12b for passage detection O 10s LT e 30 B 3 13 q flow rate veh h k density veh km O time occupancy ratio per cent O space occupancy ratio per cent v speed km h h headway S L spacing m L vehicle length m Lp effective detection zone length m t occupancy time seconds and t vehicle passage time seconds In traffic theory Equation B 3 11 is known as the fundamental traffic flow relationship From Equations B 3 12b and B 3 13 it is seen that space occupancy and time occupancy ratios are equiv alent with passage detection O O B 3 4 Basic Relationships at Traffic Signals The basic relationships given in Sections B 3 2 and B 3 3 are applicable to queue discharge and uninterrupted flow conditions at traffic signals Drivers maintain what they feel is a safe distance when following other vehicles The minimum spacing or gap length values can be observed between vehicles in a queue at signals The average spacing between vehicles in a queue is called jam spacing Ly 116 This equals the aver
93. Diamond overlap phasing allows right turns from opposing directions to operate either simultaneously or independently with the through movement on the same approach depending on demand for the right turns and conflicting through traffic on the road controlled by the diamond overlap phasing in each signal cycle see Figure 6 1 Diamond overlap phasing is controlled by three aspect right turn arrows red yellow green in a six aspect signal face or by two aspect right turn arrows yellow green in a five aspect signal face see Figures 5 4 and 5 7 in Section 5 The diamond overlap phasing is used where opposing right turn flows are too large for efficient filter operation alone at four way intersections or there are safety reasons that preclude right turn filtering being allowed The right turns can operate as optional filter turns where safety permits Filter turns are introduced after both right turn movements are stopped and both through movements are started red arrow drop out The diamond overlap phasing shown in Figure 6 1 provides leading right turns in both directions thus avoiding phase transitions that cause lagging right turn conflict where filter turns are used Section 6 3 3 43 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 6 3 6 Lead Lag Right Turn Phasing Lead lag right turn phasing combines the leading and lagging right turn arrangements i e a right turn phase precedes the phase in whi
94. FT TURN sign R2 6L NO RIGHT TURN sign R2 6R and NO TURNS sign R2 7 signs are used for banning turning movements Turn bans can be full time or part time limiting its operation to certain times of day For part time turn ban no turn signs R2 6L and R2 6R are used with a Time of Operation supplementary plate R9 1 showing the times the turn is banned as shown in Figure 11 5 also see Section 11 2 2 NO LEFT TURN or NO RIGHT TURN may be controlled by internally illuminated signs as an alternative to R2 6L and R2 6R signs see Section 11 2 3 Special vehicles may be excepted from the turn ban if necessary Further supplementary plates for buses R9 2 bicycles R9 3 or authorized vehicles R9 4 can be used for this purpose Figure 11 6 11 3 5 2 Must Turn Signs LEFT LANE MUST TURN LEFT sign R2 9L RIGHT LANE MUST TURN RIGHT sign R2 9R are used where a midblock through lane becomes an exclusive turn lane at the intersection This lane arrangement practice should be discouraged and avoided if possible as it can lead to lane change accidents AUSTROADS Figure 11 4 Signs to control turning movements at signalised intersections Turn Ban signs R2 6L R2 6R R2 7 Must Turn signs 77 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Figure 11 5 Supplementary time of operation plates for part time turn bans R9 1 Ow MON FRI 7 95 MON FRI
95. GNALS Figure 5 7 Five aspect signal face layout with yellow and green right turn arrow aspects 00 o o Figure 5 9 Four aspect signal face layouts with single right turn green arrow aspect e e o9 o oe Figure 5 8 Five aspect signal face layout withred and yellow right turn arrow aspects 2 Figure 5 10 Four aspect signal face layout with single right turn red arrow aspect 69 5 4 3 Four Aspect Signal Face Layouts with Right Turn Arrow Aspects Single Right Turn Green Arrow Aspect A four aspect signal layout with single green arrow aspect Figure 5 9 may be used only when the right turn green arrow display is always terminated simul taneously with the circular green display i e when the circular yellow display is introduced Single Right Turn Red Arrow Aspect A four aspect signal layout with single red arrow aspect Figure 5 10 may be used only when its use is restricted to the sequence discussed in Section 5 7 3 Figure 5 22 This signal face layout is used infrequently It may be used to delay a filter right turn movement for the protection of pedestrians or special vehicles 24 5 5 Face Layouts with Left Turn Arrow Aspects 5 5 1 Six Aspect Signal Face Layouts with Left Turn Arrow Aspects A six aspect signal face layout with red yellow and green arrow aspects can be used to independently control left tur
96. GNALS 10 SPECIAL ALL RED There are no special all red features 11 GAP 1 This is the first gap setting for each phase In Figure D 15 these are A B1 and C A1 detectors The gap setting is e 2 5 s for A and B1 detectors and e 2 0 s for C A1 detector 12 GAP 2 This is the second gap setting for each phase In Figure D 15 these are B2 and C A2 detectors The gap setting is e 2 5 s for these detectors 13 14 GAP 3 and GAP 4 These are not applicable since there are only two approach timers per phase see Figure D 15 15 22 HEADWAY and WASTE Similar to the GAP time settings HEADWAY and WASTE time settings are required for the first and second approach timers only Headway settings are 0 7 s for A B1 B2 and C A2 detectors and 0 6 s for C A1 detector right turn movement Waste settings are usually determined as 10 per cent of maximum green values implying 3 5 s for Phases A and B and 1 4 s for Phase C However these are less than the minimum values see Appendix C Table C 2 Therefore waste settings are 4 0 s for A B1 B2 and C A2 detectors and 2 0 s for C A1 detector SPECIAL ALL RED SEQUENCES This is not applicable PROHIBITED SEQUENCES Transition from Phase A to Phase C due to skipping of Phase B is prohibited so that both approaches of Main Road display yellow signals simultaneously to avoid a possible filter right turn conflict problem for the South approach of Main Road see Section 6
97. GUIDE TO TRAFFIC ENGINEERING PRACTICE SERIES 7 Traffic Signals THIRD EDITION g gt m y 3 gt Standards Australie STANDARDS AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 Guide to Traffic Engineering Practice Traffic Signals THIRD EDITION Accessed by AR M VICROADS on 02 Jun 2005 Guide to Traffic Engineering Practice Part 7 Traffic Signals First Published 1987 Revised Edition 1993 Reprinted 1997 3rd Edition 2003 Copyright Austroads Inc This work is copyright Apart from any use as permitted under the Copyright Act 1968 no part may be reproduced by any process without the prior written permission of Austroads National Library of Australia Cataloguing in Publication data Guide to Traffic Engineering Practice Part 7 Traffic Signals ISBN 0 85588 622 6 Austroads Publication No AP G11 7 03 formerly NAS 54 9 Technical writer and editor Rahmi Ak elik Ak elik and Associates Pty Ltd Austroads project manager Martin Chelini VicRoads Project coordinator Michael Tziotis ARRB Transport Research Ltd Technical contributors in alphabetical order by first name Bill Sissons New Zealand Bob Mudford Roads and Traffic Authority New South Wales Branko Stazic Transport South Australia Colin Foot Transport South Australia David Jones Brisbane City Council David Nash VicRoads David Stewart Queensland Department of Main Roads Gary V
98. IK R BIGGS D C and LAY M G 1983 Modelling Acceleration Profiles Internal Report AIR 390 3 ARRB Transport Research Ltd Vermont South Australia AK ELIK R CHUNG E and BESLEY M 1998 Roundabouts Capacity and Performance Analysis Research Report ARR No 321 ARRB Transport Research Ltd Vermont South Australia Revised edition 1999 AK ELIK R ROPER R and BESLEY M 1999 Fundamental Relationships for Freeway Traffic Flows Research Report ARR 341 ARRB Transport Research Ltd Vermont South Australia AUSTROADS 1988 1999 Guide to Traffic Engineering Practice GTEP Association of Australian State Road and Transport Authorities Sydney Australia Part2 Roadway Capacity 1988 Part3 Traffic Studies 1988 Part4 Road Crashes 1988 Part5 Intersections at Grade 1988 Part6 Roundabouts 1993 Part 8 Traffic Control Devices 1988 Part 13 Pedestrians 1995 Part 14 Bicycles 1999 Part 15 Motorcycles 1999 AUSTROADS 1995 Design Vehicles and Turning Paths Association of Australian State Road and Transport Authorities Sydney Australia AUSTROADS 2000 Guide to the Selection of Pavement Surfacings Association of Australian State Road and Transport Authorities Sydney Australia pp 12 17 BASTABLE A J 1980 The economic and social impact of dynamic signal co ordination in Sydney Proc ARRB 10th Conf 10 4 pp 245 251 ARRB Transport Research Ltd Vermont South Austral
99. IX D WORKED EXAMPLE D 4 Proposed Geometry and Phasing D 4 1 Description and Input Data for Design 2 The proposed intersection layout Design 2 is shown in Figure D 6 It is similar to that of Design 1 with the exception of the following changes made to the North approach a An exclusive right turn lane 2 8 m wide and 80 m long short lane is provided b The median strip is reduced from 4 5 m to 1 7 m wide c A left turn slip lane 3 0 m wide and 70 m long short lane is provided d The pedestrian crossing between the footpath and the traffic island is not signalised The proposed signal phasing system is shown in Figure D 7 Because the exclusive right turn lane added to the North approach will be arrow controlled a leading Figure D 4 Average delay and level of service estimates for Design 1 based on default actuated signal settings Main Road North 630 0 21 10 4 D e 4 43 3 ps T o v o sl T v o m S e s 2 We 9 4 o w m ef E mah 17 5 28 1 59 9 Main Road South Main Road North LOS F LOS C LOS B a 2 LOS E o Jm EE 5 f v o sd ol ot 2 N o o pd gy o LOSB LOSC LOSE Main Road South AUSTROADS 141 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS right turn sequence is used as the opposing filter right turn has been retained Phase C added A lagging right turn sequence has safety problems in this ca
100. Implementation of performance objectives for traffic light signals Proc ARRB 7th Conf 7 5 pp 226 245 ARRB Transport Research Ltd Vermont South Australia HULSCHER FR 1975 Photometric requirements for long range road traffic light signals Australian Road Research 5 7 pp 44 51 HULSCHER FR 1976 Traffic signal facilities for blind pedestrians Proc ARRB 8th Conf Session 25 pp 13 26 ARRB Transport Research Ltd Vermont South Australia HULSCHER FR 1977 Reliability aspects of road traffic control signals Traffic Engineering and Control 18 3 pp 98 102 HULSCHER F R 1980 Determination of intergreen time at phase changes In Driver Observance of Traffic Light Signals Hulscher FR et al Appendix E Report to Traffic Authority of New South Wales Sydney HULSCHER FR 1984 The problem of stopping drivers after termination of the green signal at traffic lights Traffic Engineering and Control 25 3 pp 110 116 HULSCHER FR and SIMS A G 1974 Use of vehicle detectors for traffic control Traffic Engineering and Control 15 19 pp 866 869 HUNT P B ROBERTSON D I BRETHERTON R D and WINTON R I 1981 SCOOT A Traffic Responsive Method of Coordinating Signals Laboratory Report LR 1014 Transport and Road Research Laboratory Crowthorne Berkshire U K ITE 1994 Determining Vehicle Signal Change and Clearance Intervals An Informational Report of the Institute of Transpor
101. Red to Steady Red for a short period e g 2 seconds to Off 5 8 3 Procedure without Pedestrian Displays When pedestrian signal aspects are not provided or are not operating at an intersection pedestrians may be controlled by the circular vehicle displays subject to legislation 5 9 Bicycle Signals Signal face layout and sequence requirement for bicycle signals are discussed in this section For further information on bicycle signals see Section 15 6 and Appendix C 6 34 5 9 1 Signal Face Layout Where permitted by legislation a bicycle signal face layout consists of a red bicycle aspect mounted above a green bicycle aspect Figure 5 1 These two aspect bicycle lanterns must never be incorporated with vehicle aspects in a common signal face Three aspect bicycle signals red yellow and green bicycle aspects can also be used to separately control bicycle movements 5 9 2 Basic Sequence The basic sequence for bicycle displays with two aspect arrangement is Steady Red to Green to Flashing Red to Steady Red The sequence for bicycle displays with three aspect arrangement is Green to Yellow to Red to Green 5 9 3 Procedure without Bicycle Displays When bicycle signals are not provided at signalised intersections bicycles on the roadway are controlled by the vehicle displays 5 10 Special Vehicle Signals 5 10 1 Signal Face Layout Where permitted by legislation a special vehicle signal face layout consists
102. Special inputs tram train CONTROLLER External monitoring facilities Special outputs tram train emergency services eg firebrigade ambulance Serial communication facility emergency services eg firebrigade ambulance Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS SMI control works in the same way as fully actuated control except that maximum green times are deter mined by the regional computer subject to a max imum cycle time using SCATS green split algorithms on a cycle by cycle basis according to varying demand conditions As a result of this SMI control offers advan tages over traditional fully actuated control Ak elik Besley and Chung 1998 9 2 3 Semi Actuated Control In this type of control usually only minor movements e g side road traffic are actuated Non actuated phase usually major movement receives minimum green duration but green period is extended indefinitely until an actuated phase demand is received Midblock signalised crossings with pedestrian actuation only i e where the vehicle movements are not actuated are of this type 9 2 4 Fixed Time Control Fixed time control provides only a fixed sequence and duration of signal displays This is rarely used in Australia because of its inefficiency and lack of flexibility Coordinated signal control has some elements of fixed time operation e g using a specified cycle time for all in
103. Switched lamp circuits lt Vehicle lanterns Monitoring and Pedestrian lanterns Switched lamp circuits failsafe switching Pedestrian demand indicators Pedestrian pushbutton indicator Pedestrian demand Monitoring data Pedestrian pushbutton destri traffic 14 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 SIGNAL SYSTEM AND COMPONENTS Table 4 1 Traffic signal components section numbers refer to this guide Component Purpose Specifications Section Comments Signal lanterns Provide signal display AS 2144 AS 1742 5 A Signal visors Restrict visibility and sun phantom AS 2144 7 A Signal louvres Restrict visibility and sun phantom AS 2144 and local 7 A Target boards Provide good visual background AS 2144 5 7 A Traffic signal lamps Traffic signal posts Lantern straps Post brackets Traffic signal mast arms Joint use mast arms and posts Multicore traffic signal cables Ducts pits conduits Terminal assemblies Signal controller Loop vehicle detectors Loop feed cable and loop cable Pedestrian push button assembly for lanterns Light source for the lanterns Support signal lanterns mounted beside the roadway Attach signal lantern to posts Attach signal lantern to posts Support signal lanterns mounted above the roadway Support lanterns and other utilities usually street lights Reticulation of power from controller
104. This leads to increased cycle time Maximum green settings should be selected to avoid very long cycle times in order to ensure acceptable levels of service The recommended maximum cycle time for a two phase intersection is 100 to 120 seconds subject to signal coordination considerations and is 150 to 180 seconds for sites with complex phasing systems and high traffic demands C 3 Actuated Controller Operation This section presents a description of how actuated signal controllers work Although the discussion is relevant to actuated controllers generally some specific aspects of controller operation are valid for the Australian controllers only RTA 1991 Akcelik 1995b At vehicle actuated signals the green times and hence the cycle time are determined according to the vehicle demands registered by detectors Section 8 This may be on the basis of phase control or group movement control see Section 6 1 Phase sequence may be fixed or variable A phase can be skipped when there is no demand for it A phase or signal group consists of various intervals as discussed in Sections C 3 1 and C 3 2 C 3 1 Vehicle Phase Intervals The vehicle phase signal group intervals are shown in Figure C 1 This does not include the early cut off interval which is discussed in Section C 4 5 The running part of the phase corresponds to the period when the green signal is displayed It is the period between the phase start and the phase ch
105. Timing Card shown in Figure D 16 settings reduced values used in the aaSIDRA are discussed below The following paragraph numbers analysis less the minimum green time Gsmax match the Time Setting Numbers in the Timing Card Gmax Gmin Therefore Gemax 35 8s 275 and in the controller for Phases A and B and G 14 6 8 s for Phase C are recorded in the Timing Card PHASE TIME SETTINGS It is important to note that maximum green 1 RED YELLOW extension settings should be selected on the d ahi ler und aid basis of analyses carried out for different flow Not pu b gt ae n E bici m a periods see Section D 1 to satisfy requirements sites on y en wd on sear ANG 1S of different demand patterns and different not in aaea ance with current standards as seen demand flow levels in those periods in Section 5 7 7 ECO Early Cut Off Green 2 LATE START Not applicable since there are no staged The Phase A late start interval is used to hold terminations of movement the Phase C right turn red arrows at the start of Phase A in order to protect the pedestrian 8 YELLOW movement in front of the West approach The values shown are based on the calculations 3 MINIMUM GREEN given in Section D 3 1 d 9 ALL RED Minimum green is Gmin 8 s for Phases A and B and 6 s for Phase C AUSTROADS The values shown are based on the calculations given in Section D 3 1 d 151 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SI
106. VEITH G J 1996 Roads for Cyclists In Traffic Engineering and Management Eds K W Ogden and S Y Taylor Institute of Transport Studies Department of Civil Engineering Monash University Melbourne Australia Reprinted 1999 pp 313 333 VICROADS 1997a Traffic Management Traffic Engineering Manual Volume 1 VicRoads Melbourne VICROADS 1997b Linking Traffic Signals to Railway Level Crossings Unpublished Document VicRoads Melbourne VINCENT R A MITCHELL A I and ROBERTSON D I 1980 User Guide to TRANSYT version 8 Transport and Road Research Laboratory Report LR 888 Crowthorne WEBSTER F V and COBBE B M 1966 Traffic Signals Road Research Technical Paper No 56 HMSO London WELFORD A T 1969 Fundamentals of Skill London Methuen 157 Accessed by AR M VICROADS on 02 Jun 2005 Information Retrieval Austroads 2003 Guide to Traffic Engineering Practice Part 7 Traffic Signals Sydney A4 184 pp AP G11 7 Keywords Bicycle Cycle traffic signals Delay Design Design speed Detection Dividing line Driver behaviour Fixed time signals Gap acceptance Junction intersection Interchange Lantern Layout Level of service Linked signals Parking Pavement marking Pedestrian Pedestrian crossing Performance Public transport Queue Road marking Road user Roundabout Safety Sight distance Signalisation Signalised crossing Traffic control Traffic flow Traf
107. Visors Visors are generally used to a minimise sun phantom effects and b reduce the possibility of a signal being seen by traffic for which it is not intended Louvres Louvres may be used to a minimise sun phantom effects when oriented horizontally and b reduce the possibility of a signal being seen by traffic for which it is not intended As louvres constrict light distribution their use should be restricted to essential locations Target Boards Target boards surround the signal lantern in order to improve the visibility of displays Black target boards provide the best conspicuity Symbolic Masks A mask can be used to create an arrow symbol or letter e g B or T to dedicate the aspect to a particular vehicle movement e g turning traffic or a special vehicle movement e g bus tram 4 2 3 Lantern Supports Posts poles brackets and straps are used to support the signal lanterns at the required height AS 2339 Lanterns may also be fixed to existing power reticulation poles and street lighting poles to reduce the number of poles at a particular site Typical examples are illustrated in Figure 4 2 also see Section 7 5 8 AUSTROADS SIGNAL SYSTEM AND COMPONENTS 4 2 4 Power Reticulation The supply of power throughout the signal installation is made via traffic signal cable which is laid underground in ducting Changes of direction in the ducting are made at junction pits Junction boxes and t
108. Y ENTRY RESTRICTED WHEN FLASHING sign in an assembly with flashing yellow lights e g as shown in Figure 15 4 Freeways that operate at or near capacity for significant periods of the day are suitable for the deployment of ramp metering systems For motorist acceptance and compliance the system must operate efficiently and not appear to unnecessarily delay ramp traffic Many ramp metering systems are operated in conjunction with freeway control systems In this case ramp metering controllers are connected to a central computer that processes data from detectors on the freeway and ramps and computes appropriate ramp flow rates Figure 15 4 Freeway ramp metering signals Freeway on ramp ONE VEHICLE ONLY ON GREEN SIGNAL Freeway traffic d Optional sign FREEWAY ENTRY RESTRICTED WHEN FLASHING AUSTROADS 101 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 15 9 Special Intersection Treatments 15 9 1 Seagull T Intersections The purpose of a seagull treatment of a signalised T intersection is to avoid stopping through vehicles on the major road approaching from the left of the T junction stem as seen in Figure 15 5 a This through movement is not signal controlled and operates contin uously as seen in Figure 15 5 b However this move ment could be signalised in order to make provision for pedestrians crossing When there is pedestrian demand the throug
109. a a Dace aga dena ade Speen es 7 2 4 Crash Data i bs ees A Mande ends Ponda aa ade Men a Bond ha We Sek 8 2 5 Future Developments 8 3 Geometric Elements 9 3 1 General css a a on D oe nee a E Fuer Et EE 9 9 3 2 Traffic Lanes 2225 ae Pe LAS NS eee BAG ek bE eee ee E een 9 N 3 2 1 Lane Arrangements 9 3 3 2 2 Right Turn anes 2 rro dira s oc EUER ORC o pei We acis 9 S 3 2 3 Left Turn Lanes 10 3 3 Corner Kerb Radius sisne uie kites iCal ledio tec cuc Babak een yale 11 3 3 4 Median Islands ices isos one ie oa ee ee c Be ne OO da ne AR ERR 11 T 3 4 1 Divided Roads 11 gt 3 4 2 Undivided Roads with Small Median Islands at the Intersection 11 3 5 Painted Medians and Islands 11 T 3 6 Kerbside Allocations 12 D tT 12 8 3 6 2 BUS ZONES d i a nds se Rupa shee pes Pla ree Renee er Ra a ad ee ghana eae neta dee 12 3 3 7 Service Roads sita te ocio he tives Sec ae esta ue nt ertet Leine Dos 12 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 4 viii Signal System and Components 4 1 4 2 4 3 Signal Face Layouts and Display Sequences 5 1 5 2 5 3 5 4 5 5 5 6 5
110. a given reference point Also see Demand Flow Demand Volume Traffic Count Traffic Volume xviii Flow Ratio The ratio of arrival demand flow rate to saturation flow rate during a given flow period Full Control Control of a turning movement using three aspect red yellow green turn arrows on a six aspect signal face where the green arrow indicates that the vehicle can turn unopposed with no opposing vehicle or pedestrian traffic and the red arrow indicates that the vehicle is not permitted to turn filter turns not permitted Fully Actuated Control see Traffic Actuated Control Fully Adaptive Control A signal coordination method that generates appropriate signal timing plans on line in a continuously variable fashion using extensive data provided by vehicle detectors Gap Setting A controller setting equivalent to a predetermined space time measured between successive vehicles at the given approach speed detection zone length and vehicle length values Also see Space Time Give Way Line A broken line double continuous lines in New Zealand known as limit line marked across all or part of a road behind which vehicles should slow down and give way to opposing traffic Also see Stop Line Green Band see Bandwidth Green Time Duration of the green display for a phase or a move ment Also see Effective Green and Red Times Guide Sign A sign which is erected to inform and advise road users of directio
111. ackground luminance Contrast can also be reduced by sun phantom that raises the level of reflected light from un energised signal aspects making detection of the energised signal difficult Because signals cannot normally be placed on the direct line of sight of an approaching driver an allow ance has to be made for the reduced visibility of signals located eccentrically to the line of sight As shown by Fisher and Cole 1974 the research into effects of background luminance visibility range eccen tricity of signals to direct line of sight sun phantom and related factors can be applied to develop a signal intensity specification based on a high probability of detection and minimum reaction time A 3 2 Visual Acuity Visual acuity describes the ability of the eye to distin guish fine detail ability to see clearly Poor visual acuity resulting from congenital or age related eye defects can usually be corrected by supplementary refraction i e spectacles However mild refractive error is not a serious handicap in every day life and is relatively common Poor visual acuity is significant in the reading of signs for example a person with poor acuity may need to stand at half the reading distance of a person with normal visual acuity to read a sign legend equally well Shape coded light signals such as arrows and human figure outlines are more tolerant to the effects of blur Smith and Weir 1975 Because of the effects of irra
112. affic signals where a slip lane is provided for left turn move ments not controlled by the signals and where the slip lane falls clearly within the boundary of the intersection sign R2 16 shown in Figure 11 8 This sign shall be located in such a position that it clearly applies to the slip lane In some jurisdictions a GIVE WAY R1 2 sign is used instead of the TURN LEFT AT ANY TIME WITH CARE sign AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 Figure 11 8 TURN LEFT AT ANY TIME WITH CARE R2 16 sign for slip lanes TURN LEFT AT ANY TIME WITH CARE SIGNS 11 3 9 Hook Turn Only Sign The RIGHT TURN FROM LEFT ONLY sign Figure 11 10 is used at an intersection controlled by traffic signals where right turning drivers are required to make a Hook Turn This manoeuvre consists of entering the intersection from the far left side of the approach road moving forward while keeping to the left of the inter section and clear of any signalised crossing waiting in that position until the traffic lights on the road to the right change to green and then turning into that road This sign shall be located in such a position that it is clearly seen by drivers approaching the intersection e g overhead location 11 3 8 LEFT TURN ON RED PERMITTED AFTER STOPPING Sign The LEFT TURN ON RED PERMITTED AFTER STOP PING sign is used to allow vehicles on any approach where this sign is displayed to turn left
113. affic movements at a signalised intersection into sequential and concurrent overlapping traffic streams to form a complete sequence of phases This sequence of phases is called a cycle Two methods exist for the implementation of phasing arrangements in signal controllers a Phase contro whereby the signal timing para meters intergreen time minimum green time etc are specified for phases Phase control tries to minimise the number of phases in order to decrease the intersection lost time b TZ Group control whereby the signal timing para meters are specified for movements Group control tries to maximise the amount of overlap movements so as to minimise the total time for all critical movements to operate regardless of the number of phases This control method permits more flexible and efficient operation and suits more complicated phasing systems These two control methods do not necessarily repre sent the operation of any particular type or make of controller The controllers used in Australia employ features of both phase and group control methods 6 2 General Requirements for Signal Phasing This section discusses fundamental aspects of signal phasing All of the guidelines or rules apply irrespective of the number or sequence of phases Sections 6 3 to 6 5 present detailed discussions on phasing design Permissible and recommended signal display combi nations and sequences are described in Section 5 Det
114. age vehicle length L plus the average jam gap length Lj measured from the back of the leading vehicle to the front of the following vehicle in the queue Lni The density that corresponds to the jam spacing is called the jam density i e the number of vehicles per unit distance in a stationary queue in veh km kj 1000 Ly B 3 15 As vehicles speed up from a stationary queue the gap length between vehicles increases gradually and therefore the spacing increases as a function of speed After an initial acceleration period vehicles departing from a queue at traffic signals cross the stop line with approximately constant headways This is the minimum saturation headway h which corresponds to a maximum flow rate known as saturation flow rate qn s 3600 h Other corresponding parameters include the saturation speed v spacing at saturation flow L occupancy time at saturation flow t and so on Lj L B 3 14 ond Under uninterrupted flow conditions as applicable after queue has been cleared at signals vehicle spacings and headways increase and the flow rate and density decreases as the speed increases towards the free flow speed v9 The maximum flow rate at traffic signals can be obtained during fully saturated green periods Capacity is the maximum hourly flow rate that can be achieved with allowance for the green time available Other important parameters used in the timing and perfor mance a
115. ailed discussion of sequences with arrow aspects including various examples is presented in Section 5 7 6 2 1 Fundamental Rules Signal phasing provides the mechanism by which the basic safety and efficiency requirements of vehicle and pedestrian movements at a signalised intersection are met Thus the objectives of signal phasing design are a safety reduce crashes by managing and minimising conflicts among movements with particular consideration given to conflicts with an accident history and b efficiency minimise delay queue length or number of stops or a combination of these operational performance measures or maximise throughput Ak elik 1981 The above objectives often conflict and appropriate compromises need to be found In minimising delay queue length and number of stops the average values of these measures for all movements at the inter section as well as the individual movement values should be considered Driver understanding and acceptance of the system and uniformity at the intersections in an area con sistency are important considerations in signal phasing design Accessed by AR M VICROADS on 02 Jun 2005 The choice of phasing system depends on the following factors a layout the number of lanes available for each movement on the approach and departure of each intersecting road b TZ alignment the horizontal and vertical alignment in regard to the angle roads intersec
116. al Secondary Signal Face The signal face mounted on a post on the downstream side to the right of that approach in addition to the secondary signal face located on the median Early Cut Off The phase interval used at the end of a phase for allowing the termination of some signal groups earlier than others Effective Green and Red Times The movement green and red times for capacity and performance analysis purposes which are determined by adjusting the displayed green and red times for Start Loss and End Gain effects Also see Green Time Red Time Eighty fifth Percentile Speed see Speed End Gain Duration of the interval between the end of displayed green period and the end of effective green period for a movement This is used in signal timing and perform ance analysis to allow for additional departures after the end of green period Early Cut Off time can be treated as an end gain for the movement that is terminated at the end of the Early Cut Off interval Also see Start Loss xvii Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Exclusive Pedestrian Phase The phase at an intersection during which all pedestrian displays are green and all vehicle displays are red allow ing all pedestrian movements to operate simultaneously while all vehicle movements are stopped Also see Scramble Crossing Phase Exclusive Lane A lane or length of lane allocated for use only by a particular movement or a type of ve
117. al phasing designs can be developed for a given intersection in accordance with the criteria given in Section 6 2 1 The relative effectiveness of alternative phasing designs can be evaluated using computer software packages that offer analytical or simulation techniques for esti mating operational performance measures Section 14 describes how the chosen phasing can be checked in operation 6 2 3 Crash Risk Factors Safety evaluation is a prime consideration in selecting a phasing design The following factors are expected to contribute to significant increases in risk of crashes involving turning movements that filter through opposing vehicle and pedestrian movements a The sight distance from the turning vehicle to conflicting vehicles or pedestrians is inadequate b There is more than one lane of turning traffic c Parallel pedestrian movements are exposed to i high volumes of turning traffic ii high turning traffic speeds resulting from the turn geometry or d The 85th percentile speed of the opposing traffic is greater than 70 km h and the right turning traffic has to turn across three or more lanes of oncoming traffic e Lagging right turn with opposing filter turn this conflict must be avoided as discussed in Section 6 3 3 6 3 Phasing Design Figure 6 1 presents definitions of basic elements of phasing that are applicable to four way or three way intersections cross intersections or T ju
118. allocated to a movement Section C 4 2 1 The variable initial green interval is used with advanced detectors to provide additional minimum green time to discharge a queue of vehicles stored between the stop line and detectors during the red period The duration of this interval varies in response to the number of actuations of the advance detectors and is determined according to the values of the Vehicle Increment and Maximum Initial Green Settings Section C 4 2 2 The controller cannot enter the extension green interval until a demand for another phase is registered The rest interval is an untimed interval after the minimum green time expires during which the controller rests until a demand for another phase is registered as shown in Figure C 1 The rest interval is skipped if a demand is registered for other phases before the end of the mini mum green time The extension green interval is of variable length and under isolated operation its duration is deter mined by extension settings namely the Gap Setting 124 Section C 4 4 Headway and Waste Settings Section C 4 7 2 and Maximum Extension Green Setting Section C 4 3 In the case of parallel vehicle and pedestrian movements at intersections the pedestrian Walk and Clearance 1 intervals can hold the extension green interval Sections C 3 2 and C 5 The Gap Headway and Waste Settings are used as space non occupancy time values as measured by presence detection
119. an be mathematically expressed as tj t 0 5 vp 3 6 aj 9 8 G C42 subject to tz 3 0 where t Yellow Time s t reaction time s vp design speed km h ay the deceleration acceptable to the majority of drivers m s2 and G approach grade per cent grade divided by 100 negative value for downhill grade and positive value for uphill grade e g 0 05 for 5 per cent downhill grade The Yellow Time values calculated as a function of the approach grade using a 3 0 m s t 1 0 and 1 5 seconds in Equation C 4 2 for the design speeds of vp 50 60 70 and 80 km h rounded to the nearest 0 5 seconds are given in Table C 3 C 4 6 2 All Red Time An all red interval is used between the end of the yellow interval of a phase or signal group and the commence ment of the green on the next phase or signal group The purpose of the all red interval is to provide a safe clearance for vehicles that cross the stop line towards the end of the yellow interval since they may be in danger of collision with vehicles or pedestrians released in the following phase or signal group 131 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS As seen in Table C 2 typical All Red Times used in practice are in the range 1 0 to 3 0 seconds The timing of an all red interval should take account of the speed of vehicles crossing the stop line at the end of the yellow interval the distance to the furthest pote
120. ance from Signalised Crossing The push button should be located not more than 1 m outside the projection of the signalised crossing nor more than 2 m back from the kerbline at the signalised crossing f Push Button Posts A special push button post should be installed if no traffic signal post can be located in a suitable position Audio Tactile Buttons These shall not be closer than 2 m from one another AS 1742 Part 14 For this reason two push buttons on one pole is not suitable for audio tactile push buttons VS g AUSTROADS TRAFFIC DETECTION 8 5 Special Traffic Detection Special detection methods are used for particular types of traffic including buses and trams see Section 15 5 3 bicycles emergency vehicles and railway traffic 8 5 1 Buses Normal loop detectors may be used for bus detection where Bus Only lanes are provided Where buses share lanes with other traffic one technique used involves an on bus transponder transmitter which is a device fitted to the bus This identifies the presence of a bus to a roadway sensor In some applications a bus is detected only when such device is actuated by the driver Other techniques may be used which utilise a combinations of detectors which either identify the bus by its length or its height above the road surface or b classification detectors which identify the bus by special loop detectors 8 5 2 Trams Three methods of tram detection are cu
121. and Roper 1999 reported a typical queue departure response time of 1 15 s observed at intersections in Melbourne and Sydney The assembly is generally erected on the left of the approach However if it cannot be seen in this position due to restricted sight distance caused by horizontal left hand curvature the assembly should be erected on the right of the approach The assembly may also be mounted overhead if the sight distance to a side mounted sign is restricted by vertical road curvature Refer to Appendix B 2 1 for a discussion of vehicle braking characteristics and stopping distance 15 3 Railway Level Crossings 15 3 1 Proximity to Level Crossing If a road signal installation is located in close proximity to a railway level crossing such that there is a probability that a vehicle queue generated by the road signals will 96 extend across the rail tracks special provision should be made to force the road signals to a phase that will clear the queue before the arrival of the train The signal requirements should be determined in consultation with the appropriate railway authority Use of yellow box pavement markings and fixed or variable message signs such as KEEP TRACKS CLEAR may be effective in preventing vehicles queuing over rail crossings Some examples and guidelines for good practice have been documented by ITE Technical Committee TENC 4M 35 ITE 1997 Guidelines for the operational requirements of traffic
122. and that under fault conditions the signals should revert to flashing yellow Therefore flashing yellow AUSTROADS SIGNAL FACE LAYOUTS AND DISPLAY SEQUENCES should not be used as a regular routine mode of operating intersection signals for example under light traffic conditions A survey of accident data Middleton 1969 has confirmed that even under light traffic con ditions it is advantageous to retain normal operation of signals 5 11 2 Signal Display on Start Up When initiating operation of a signal controlled intersection the following sequence of displays is recommended a display Flashing Yellow on all approaches for a minimum of ten seconds b TZ display Steady Red on all approaches for three seconds minimum c display Green aspects to the first usually preselected movements to proceed d introduce a cyclic display of all phases and movements lt e proceed with normal operation 35 Accessed by AR M VICROADS on 02 Jun 2005 6 Signal Phasing 6 1 Introduction and Scope Signal phase is a state of the signals during which one or more movements receive right of way subject to resolution of any vehicle or pedestrian conflicts by priority rules phase is identified by at least one movement gaining right of way at the start of it and at least one movement losing right of way at the end of it Signal phasing covers the arrangements of separately controlled tr
123. ands for a Phase Detectors initiate a demand for a phase i e call a phase This is usually done for vehicles waiting against a red signal The demand can be a locking call in which case the call is only cancelled when the requested phase runs The location of detectors for locking calls requires that only vehicles serviced by the demand phase be detected Presence or passage detection mode can be used The demand can be a non locking call in which case the call is cancelled when the detector input is removed Non locking calls are used for approaches or lanes where the vehicle may leave the approach before the called phase occurs for example i a right turn phase is no longer needed when right turn vehicles filter before the turn phase is displayed or 62 ii a side street phase is no longer required if the waiting vehicle turns left when a left turn green arrow display occurs in the preceding phase e g a three phase T intersection case with overlap left turn and right turn movements or iii where left turn on red is permitted Non locking calls can be achieved by presence detection only The detector loops must be located so that the vehicle waiting for the called phase is detected 8 3 2 2 Conditional Demands In some situations a conditional demand is required to detect stopped or slow moving traffic see Section 8 3 4 3 A call is not registered until the detector is occupied for a minimum set time presen
124. ange points The clearance part of the phase corresponds to the period when the yellow and all red signals are displayed It is the period between the phase change point the end of running intervals and the beginning of the green display for the next phase end of phase Green time is the duration of running intervals and the intergreen time is the duration of Yellow Time and All Red Time 123 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Figure C 1 Definition of phase signal group intervals for vehicle traffic Start of Phase Running Intervals Green Demand for Minimum Green another phase registered Red Time gt End of Phase Phase change point Clearance Intervals Intergreen Red Time Initial Extension Green For advance detection only Yellow All Red Different signal indications can be displayed to different movements using the phase during the late start and early cut off green intervals The late start interval is used to delay the introduction of green signal to some movements in the phase The durations of these intervals are determined by the Late Start and Early Cut Off Green Settings Sections C 4 1 and C 4 5 The two minimum green intervals used for safety reasons are the basic minimum green interval and variable initial green interval Section C 4 2 With stop line detectors a Basic Minimum Green Setting determines the minimum green time
125. angement of separately controlled groups of vehicle and pedestrian movements within a signal cycle to allow all vehicle and pedestrian movements to proceed Signal Range Visual Range The distance over which the signal is intended to be clearly visible to approaching traffic Signal Sequence see Display Sequence AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 Signal Timing The process of determining durations of successive intervals of green yellow and red displays actuated signal control settings as well as offsets for coordinated signals Signalised Crossing An area of the road used by pedestrians when crossing the road with the guidance of pedestrian signals at a midblock or intersection location and can be used by cyclists if bicycle signals are provided Simultaneous Offset Coordination Signal coordination where green periods in the travel direction start at the same time zero offset This is useful when the back of queue at the downstream intersection interrupts progression at closely spaced intersections Also see Offset Slip Lane A left turn lane separated from an adjacent lane by a triangular island Space Length Gap Distance The following distance between two successive vehicles as measured between the rear end of one vehicle and the front end of the next vehicle in the same traffic lane spacing less vehicle length Space Occupancy Ratio The proportion of a road section distance occupied
126. ans have visual handicaps and therefore audio tactile push buttons and tactile ground surface indicators must be provided to cater for their needs A 3 1 Visual Sensitivity Visual sensitivity refers to the ability of the eye to respond to luminance differences in different parts of the scene and is intimately connected with contrast The threshold for detection of contrast rises with increasing age Compared with young visually fit persons it is 18 per cent higher at age 42 years and 80 per cent higher at age 64 years Older drivers therefore require a higher target light intensity to arouse the same res ponse as in young drivers Cole and Brown 1968 In the absence of other distracting or confusing light sources detection of signal displays is performed on the basis of contrast When a signal is seen against a background of high brightness such as the clear sky higher signal light intensity is necessary to maintain a high probability of detection and a short reaction time The effect of the luminance of the background can be reduced by the provision of a black target board behind the signal Cole and Brown 1966 Fisher and 109 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Cole 1974 It should be noted that in the measuring of contrast there is direct inverse relationship between the signal intensity and the amount of background screening provided by a target board of a given size under given conditions of b
127. antern It is important to communicate the correct coloured image to the eye and when glare is present this communication may not happen Glare results when the light intensity or luminance levels of the signal become so high that the eye is overloaded A light source that produces this sensory overload communicates false information and reduces the overall effectiveness of the system Dimming of signals may therefore be necessary under conditions of low ambient light The eye is sensitive to only a narrow band of wave lengths However colour perception cannot be des cribed only in terms of wavelength and in practice three inexact terms are used to describe colour a hue which is related to wavelength b saturation which refers to the purity of the colour i e how much white is in the mixture and c brightness which describes whether a colour is vivid or dim This three dimensional concept of colour was devel oped by the Commission Internationale de l Eclairage CIE into a quantitative system of colour coordinates which takes due account of the colour response of the human eye This quantitative system is based on the normalised quantities X Y and Z which are inter related by the equation X Y Z 1 The CIE chromat icity diagram uses coordinates X and Y only and forms the basis of all modern colour specifications Blevin 1972 The CIE chromaticity diagram can be found in AS 2144 and AS NZS 2633 The colou
128. ao E o m a P o a ee 3 3 ao o m 2 o u 7 1s elo 3 E 8 F Lo a oO m O a o o LOS D LOSD LOSE Main Road South 144 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 APPENDIX D WORKED EXAMPLE Main Road North 27 6 10 0 4 2 z 30 4 i e 7 o S oa T 3 9 TRIO e E o v a win Ej o a F Pe i D sw VON 9 7 er m ow a or gt 29 1 40 0 4 37 9 Main Road South Figure D 9 Average delay and level of service estimates for Design 2 with reduced maximum green settings Main Road North d LOS C LOSB LOS A a z o LOS D o o s 5 v FS a S A cl z Alo o o a o O o g o age a m ow o ox o LOSC LOSD LOS D Main Road South Finally a flow scale analysis for design life purposes is carried out using the reduced maximum green settings 70 per cent of default values In this analysis all demand flows are increased from current levels by applying an increasing flow scale factor Average green times and cycle time are recalculated under each demand flow scenario As seen in Figure D 12 these results indicate that the intersection could carry 16 per cent more traffic before it reaches the point when the spare capacity is zero i e the intersection degree of saturation equals the practical target degree of saturation of 0 90 With a uniform traffic growth of 2 per cent per year this would mean that the inter
129. arger corner kerb radii can result in the following problems a greater vehicle turning speeds which can become a problem for pedestrians crossing the road at the intersection b TZ increased clearance times and delays if stop lines are located further from the intersection longer signalised crossings or deviations from their direct route if the crossing is shortened by moving it further from the intersection and c d possible difficulties in achieving optimum lantern positioning and aiming 3 4 Median Islands 3 4 1 Divided Roads The following are the more important practices that should be observed when designing median islands at signalised intersections a a minimum clearance from face of kerb to the signal equipment usually the edge of the target board of 0 5 m is desirable to avoid both damage to the equipment and vehicles additional clearance may be needed to allow for road camber b TZ where pedestrians are likely to accumulate on medians the width should be a minimum of 1 5 2 m see AS 1742 AUSTROADS GEOMETRIC ELEMENTS c if an exclusive right turn lane is provided the residual width of median should satisfy a and b d the use of wide medians reduces capacity because of increased clearance times and it may create the problem of interlocking the opposing right turn vehicles the ends of median islands should be set back 0 6 m behind the prolongation
130. art of the document Austroads would like to acknowledge the contri butions of Ted Barton Ross Blinco Frank Hulscher and Cliff Arndt in previous editions of this guide soog unf Zo uo SQVOHOIA W HV q pesseooy Contents Glossary of Terms iine oed ree IER EPREP RE ERI de tele it ete oh does xv 1 Introduction gx gain E E E E E 1 1 1 General D D AEE E E ah E E E E SE E SET 1 1 2 SCOPE EMT 1 1 3 Statutory ProvislOns 24 04 cedes de made a e E der mate E E AE 1 1 4 Associated Standards and Manuals 1 1 5 Guidelines 2 1 5 1 Signalised Intersection Warrants 2 1 5 2 Midblock Signalised Crossing Warrants 2 1 5 3 Warrants for Pedestrian Signals at Signalised Intersections 3 1 6 Environment icu ni den men dede ueste ceret et en dew 4 1 7 D sign Process bur ph nan Lan EE ERR RE qu die aa pueda ardt que 4 1 8 LG 0 LV ED 0 Le E T 4 1 9 Operation se 4 1 10 Maintenance ic edet Gade iret b Re Mn datent dant tre Sr 6 1 11 Education and Enforcement 6 1 12 Phe gv IM 6 2 Desig L MSN 7 2 1 Introduction ORE EC OE Bd Dah Sa be ea ent ae 7 2 2 Physical Layout of Intersections 7 2 3 Trafic Data sxe ate cathe fae nea Gar ace n
131. asionally to indicate that drivers of special vehicles may proceed in the direction of the arrow Combination of Aspects Pedestrian aspects must not be combined with vehicle aspects in the same signal face Circular and arrow aspects may be combined as detailed later in this section Circular or arrow aspects can also be combined with special vehicle aspects 5 2 5 Target Boards High ambient or background lighting may decrease conspicuity of the displays The use of target boards should be considered see Figure 4 2 in Section 4 Multi column signal faces should be provided with a common target board Target boards are not used with pedestrian lanterns 5 3 Vehicle Signal Face Layouts This section discusses general requirements for vehicle signal face layouts Sections 5 4 and 5 5 discuss signal face layouts with right turn and left turn arrow aspects The sequence of vehicle signal displays is discussed in Section 5 7 5 3 1 Basic Signal Face Layouts Aspects are arranged in columns with the red aspect upper most the yellow aspect central and the green aspect at the bottom The basic three aspect signal face consists of red yellow and green circular aspects in a single column as shown in Figure 5 3 21 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS This is the normal minimum permissible signal face layout and should be used as a first preference In special traffic situations two aspect signal fac
132. aspect lanterns shall be red yellow or green Special vehicle aspects for trams buses or emergency vehicles shall be red yellow or white 5 2 3 Size of Aspects The following considerations apply in relation to the size of signal aspects a 200 mm nominal diameter general purpose aspects are suitable for most urban applications Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS b all aspects in the one signal face must be of the same size c for pedestrian aspects 200 mm nominal diameter aspects shall be used d extended range aspects with a 300 mm nominal diameter are more expensive to provide and to operate and therefore their use should be limited to the following situations i in overhead signal faces mounted on mast arms or gantries ii where circular displays must provide a greater advance warning than the normal 150 m from the signal stop line or where the 85th percentile approach speed exceeds 70 km h and iii where an arrow signal display must provide greater advance warning than the normal 80 m from the signal stop line or where the 85th percentile speed of turning traffic exceeds 40 km h 5 2 4 Types of Aspects Signal aspects currently in use are illustrated in Figure 5 1 Some aspects shown are not permitted in some jurisdictions Circular Aspects Circular aspects disks are used as a first preference They are the easiest to comprehend and have the
133. ayouts 5 3 3 Four Aspect Single Column Signal Face Layouts 5 3 4 Two Aspect Signal Face Layouts Face Layouts with Right Turn Arrow Aspects 5 4 1 Six Aspect Signal Face Layouts with Right Turn Arrow Aspects 5 4 2 Five Aspect Signal Face Layouts with Right Turn Arrow Aspects 5 4 3 Four Aspect Signal Face Layouts with Right Turn Arrow Aspects Face Layouts with Left Turn Arrow Aspects 5 5 1 Six Aspect Signal Face Layouts with Left Turn Arrow Aspects 5 5 2 Five Aspect Signal Face Layouts with Left Turn Arrow Aspects 5 5 3 Four Aspect Signal Face Layouts with Left Turn Arrow Aspects Permissible and Non Permissible Signal Face Layouts Sequence of Vehicle Signal Displays 5 7 1 Basic S QUENCE issus seuanmrsseauanmenesaunaseanauaaents 5 7 2 Sequences with Arrow Aspects 5 7 3 Right Turn S quences stesse a wae hme adeb ee 5 7 4 Left Turn Sequences 5 7 5 Sequences for Two Aspect Columns Pedestrian Signals 5 8 1 Signal Face Layout 5 8 2 Basic Sequere SLR D ns Mon 5 8 3 Procedure without Pedestrian Displays igni 13 Fund de 13 Sora 13 ire 13 13
134. be green right turn trap If the right turn movement from the direction opposing the lagging right turn cannot be banned this conflict situation must be avoided by AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 a using a leading right turn sequence Section 6 3 2 rather than a lagging right turn sequence and ensuring that the transition from the through phase to the right turn phase is avoided when the intervening phases are skipped not demanded e g in Figure 6 4 transition from Phase B to Phase A when Phase C is not demanded or b TZ forcing the overlapping through movement from the West approach in Figure 6 5 to stop and then start up again though this is not an efficient method or c using another phasing such as split approach phasing Section 6 3 4 or diamond overlap phasing Sections 6 3 5 or lead lag right turn phasing Sections 6 3 6 A similar conflict for filtering right turn vehicles can occur in any phase sequence where one through movement receives yellow signal display before the opposite through movement early cut off For example this may happen at paired intersections see Section 15 where through movements are terminated at different times in order to clear traffic from internal approaches Where it is safe to do so the arrow controlled right turn is generally allowed to filter through the opposing through movement during the preceding phase the right turn
135. be synchronised This allows offsets to be specified and maintained Synchronous linking uses a fixed cycle time but allows local vehicle actuation of minor phases within the constraints of the timing plan Although they provide a low cost solution cableless linking systems pose serious problems in maintaining the clocks in synchronism even in cities with reliable mains power However synchronisation of the signal controller clocks can be maintained using a Dial in Dial out system This system can be programmed to call each site in a linking system at regular intervals to COORDINATION OF TRAFFIC SIGNALS synchronise the signal controller clock The Dial in Dial out system can also be used to modify linking data as well as monitor on site operation Synchronous linking is the fall back mode of operation in some wide area control systems for use when the central control computer fails 13 4 3 Wide Area Control Systems Wide area control systems usually known as area traffic control ATC or urban traffic control UTC systems involve one or more centrally or regionally located com puters controlling relatively large numbers of signals These systems provide for centralised monitoring and control and often include a traffic control centre which is staffed for significant periods of the day to monitor operations and assist with relief of congested traffic conditions which result from traffic incidents and signal equipment malfunction
136. both greens shall terminate at the same time see Figure 5 15 The exceptions are a midblock Pelican crossings see Section 6 5 3 where the sequence for vehicle movements shall be Green to Yellow to Red to Flashing Yellow to Green b TZ multi column arrangements without a three aspect symbolic column or a single symbolic aspect where the sequence may include an Off condition Figure 5 18 Basic display sequence for three aspect signals OQ e 600 e O 0 5 7 2 Sequences with Arrow Aspects In sequences with arrow aspects usually in multi column displays the requirements of the basic sequence of displays discussed in Section 5 7 1 are extended as follows a Where it is desirable to allow for filter movements to take place the Off condition of a column of arrow aspects may be used Flashing Yellow may also be used see Section 6 3 AUSTROADS SIGNAL FACE LAYOUTS AND DISPLAY SEQUENCES b The alternative permitted sequences for arrows of six aspect signal faces are i Green to Yellow to Red to Off to Red to Green ii Green to Yellow to Red to Flashing Yellow to Yellow to Red to Green iii Green to Yellow to Red to Flashing Yellow to Off to Red to Green iv Green to Yellow to Red to Off to Green c The permitted sequences for arrows in five aspect signal faces are i Green and Yellow arrows Green to Yellow to Off to G
137. buses bicycles motorcycles trucks rigid vehicles semi trailers and so on TRB 2000 Chapters 2 and 8 In order to simplify vehicular traffic analysis different vehicle types are often classified into light vehicle and heavy vehicle categories Consideration of the effect of different ages of vehicles in the general vehicle population is also important in relation to critical vehicle characteristics Vehicle braking characteristics are discussed in Section B 2 Refer to Gardner 1996 Homburger et al 2001 Lay 1985 and Pline 1999 for more detailed infor mation Basic characteristics of vehicular traffic relevant to traffic signal control are discussed in Section B 3 B 2 Vehicle Deceleration and Acceleration Characteristics B 2 1 Deceleration Characteristics It is necessary to consider vehicle deceleration charac teristics in terms of braking capabilities e g for the purpose of determining yellow time and deceleration characteristics for normal operational analysis e g for geometric delay or operating cost calculations In terms of braking performance the vehicle stopping distance which is one of the most important con siderations in traffic signal design consists of the distance travelled during reaction time and the distance travelled during braking It may be expressed as 2 tr Vi Vi Ds Dr Db 36 25446 821 where D stopping distance m D reaction distance m Dy braking d
138. ccessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 14 15 xii Installation Checks and Maintenance 14 1 14 2 14 3 15 1 15 2 15 3 15 4 15 5 15 6 15 7 15 8 15 9 15 10 15 11 15 12 15 13 Precommissioning Checks 14 1 4 General 14 1 2 Check List Monitoring and Evaluation of Operation 14 241 General s c oes veh owen owe owe see d 14 2 2 Check List Maintenance cs nace ee une 14 3 1 Maintenance Management 14 3 2 Maintenance Records 14 3 3 Preventative Maintenance 14 3 4 Breakdown Maintenance 14 3 5 Lamp Replacements 14 3 6 Accident Damage 14 3 7 Cleaning and Painting 143 8 Spare Parts eee eon s ss 14 3 9 Replacement Scheduling Special Applications and Facilities Introduction Advance Warning Signals Railway Level Crossings 15 3 1 Proximity to Level Crossing 15 3 2 Linking Requirements 15 3 3 Railway Road Crossing within the Intersection 15 3 4 Conflicting Railway and Road Signals Emergency Vehicle Facilities 15 4 1 Facilitie
139. ce e g 115 m for a speed of 80 km h or ii the signals are located in an unexpected position e g temporary signals in a rural area or iii high approach speeds may lead to frequent in fringement of the signals or to accidents especially when coupled with large downhill grade This sign is usually used at the first set of signals en countered when approaching from a rural speed zone of 80 km h or more In some instances duplication of the sign on the opposite side of the road may be warranted A PREPARE TO STOP supplementary plate sign W8 27 shown in Figure 15 1 in Section 15 2 should also be considered in order to reinforce the Signals Ahead sign Under circumstances where this is considered to be inadequate flashing yellow signals should be used to attract special attention to these signs AS 1742 Part 2 gives stopping sight distance values for various design speeds 11 3 12 NOT IN USE Sign When a traffic signal installation is not illuminated the temporary NOT IN USE sign Figure 11 12 may be used to obscure at least two signal faces on each vehicular approach usually prior to the commissioning of a new set of signals Overhead displays are not normally obscured The sign has black letters minimum size 160 mm on a yellow non reflective background which may comprise either a rectangular plate shaped so as to obscure the signal display or a boot made of canvas or similar material which fits over the comple
140. ce time The call may be locking or non locking Presence detection mode is required for conditional demands and the length and location of the sensor loops is critical for this purpose 8 3 2 3 Green Extension Detectors are used to extend green displays when there is a continuous stream of approaching vehicles The most common way of extending the green period is to compare vehicle space times with a preset gap setting see Appendix C 8 3 2 4 Strategic Functions For traffic signals operating under wide area control systems see Section 13 4 3 some detectors have a dual role i Tactical to determine the demand and or duration of phases in the same way as isolated traffic signals and ii Strategic to provide information in order to enable computation of cycle length phase splits and signal offsets for system control 8 3 3 Loop Shape and Size Loop size which determines the detection zone is dependent on two factors i Longitudinal Response This is determined by the detection zone required along the roadway The length depends upon the detection function required and normally varies between 1 metre and 12 metres AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 ii Transverse Response This is determined by the transverse width of the detection zone required across the roadway The width depends upon the dimension of the target vehicles to be detected and the width of the traffic lanes The ac
141. ch both through move ments run followed by a right turn phase for the right turn movement from the opposing approach see Figure 6 7 In this phasing i the leading right turn must be fully controlled using three aspect right turn arrows red yellow green in a six aspect signal face and ii the lagging right turn can be either fully controlled using three aspect right turn arrows red yellow green in a six aspect signal face or partially controlled using either three aspect right turn arrows with red arrow drop out or two aspect right turn arrows yellow green in a five aspect signal face This phasing is useful for signal coordination purposes since it provides more predictable operation than the diamond overlap phasing Where it is safe to do so the lagging right turn move ment may be allowed to filter through the opposing through movement during the preceding through phase red arrow drop out If filtering causes safety problems this right turn must be stopped using a red arrow display when the opposing through movement is operating full control The leading right turn movement should not be allowed to filter during the following through phase i e should be fully controlled in order to avoid the lagging right turn conflict discussed in Section 6 3 3 6 3 7 Repeat Right Turn Phasing Repeat right turn phasing introduces the arrow controlled right turn twice in the same cycle see Figure 6 1 Effectively
142. cies or from the public and while the details are often insufficient response to such advice must be seen to occur within a reasonable time if future advice is to be encouraged Hulscher 1974 1977 provided a useful guide to pri ority that should be assigned to various traffic signal faults and guides to suitable response times 14 3 5 Lamp Replacements Lamp failures can occur at any time although the pro bability of failure increases as the lamp approaches its rated life Unless adequate display redundancy is provided in the design random failures will need to be repaired as break down maintenance rather than by routine servicing The application of reliability engineering techniques and those of Hulscher 1974 will allow the determination of suitable bulk group re lamping intervals to minimise the number of random failures that must be attended to and to maintain an adequate signal luminance 14 3 6 Accident Damage A high priority should be given to actions in response to reports of accident damage Minor damage may cause significant operational problems e g when conflicting displays are given to traffic Damaged equipment should be checked as soon as possible to ensure that it is electrically safe Thus attempts should be made to respond promptly to these reports It may be necessary to temporarily switch the signals to flashing yellow or off The installation should be returned to service as soon as possible 93
143. cification for the intensity distribution of the signal having regard to eccentric viewing angles met in practical situations Fisher also deduced that the relative intensities of the three colours should be in the ratios 1 1 33 3 for red green and yellow signals respectively He recommended that the amount of sun phantom from the yellow aspect should be limited to 8 3 per cent of the on axis signal intensity of the energised red and green aspects Fisher and Cole 1974 gave a summary of this develop ment Hulscher 1975 extended Fisher s work to signals for a viewing range up to 240 m The photometric specification for both types of signal is now incorporated in AS 2144 111 Accessed by AR M VICROADS on 02 Jun 2005 Appendix B Vehicular Traffic Factors B 1 General As in the case of human factors discussed in Appendix A a sound knowledge of characteristics of vehicles using traffic control facilities and a good understanding of relevant vehicular traffic factors are essential to successful implementation of traffic control measures Important vehicle characteristics relevant to traffic control include vehicle dimensions and manoeuvrability including overall size length width height mass and power to weight ratio braking deceleration acceleration visibility related to sight distance and cornering In this respect it is important to recognise different characteristics of different vehicle types such as cars vans
144. cle times result in longer delays to side road traffic and pedestrians and result in longer queue lengths In areas such as CBD networks where queue storage spaces are limited long cycle 90 times may lead to the blockage of upstream signal stop lines queue spill back and the resulting loss in the network capacity leads to increased delays and stops Signal coordination plans can be prepared manually using time distance diagrams or an off line optimis ation software e g TRANSYT Li 1988 U S Depart ment of Transportation 1988 Vincent Mitchell and Robertson 1980 and SCATES RTA NSW 1991a Preparation of signal coordination plans are also relevant to fully adaptive control systems e g offset plans for the Masterlink mode and timing plans for the synchronous linking fall back mode in SCATS Figure 13 3 Typical relationship between traffic performance and cycle length for coordinated signals Operating cost gt Cycle time AUSTROADS 14 Installation Checks and Maintenance 14 1 Precommissioni ng Checks f momentarily energise each lamp circuit to ensure that the intersection has been wired correctly 14 1 1 General i e that signal faces not associated with the circuit being energised are not energised Prior to commissioning it is necessary to check the installation to ensure that it is in accordance with the 8 check that the signal faces for each approach design and that all e
145. conds for through and left turn movements and 2 0 to 3 0 seconds for arrow controlled right turn movements A method to determine gap settings is discussed in Ak elik Besley and Roper 1999 Section 14 2 The Headway Setting and Waste Setting that are used in association with the Gap Setting are discussed in Section C 4 7 2 Analytical and simulation studies indicated that these settings do not influence the green duration as much as the Maximum Extension Green and Gap Settings e g Ak elik 1995b C 4 5 Early Cut Off Green and Early Cut Off Yellow Settings The early cut off green interval allows the termination of some signal groups earlier than others This arrange ment is shown in Figure C 4 For example at paired intersections the upstream signals may be terminated earlier than the downstream signals in order to minimise queuing on internal approaches see Section 15 9 2 The Early Cut Off Green Setting depends on inter section geometry but normally should not be less than 3 seconds The early cut off yellow interval is an auxiliary phase interval used to provide a yellow display for any signal groups that are terminated at the beginning of the early cut off green interval The early cut off green interval follows the phase change point and is considered to be part of the clearance interval intergreen time 129 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Figure C 4 Early cut off g
146. ctuated Control 70 9 2 4 Fixed Time Control 70 9 3 Selection of Appropriate Control 70 9 3 1 Facilities RAR Sd en de at nn Ne Rae Rae 70 9 3 2 Controller Capacity 71 9 3 3 Controller Operation and Maintenance 71 9 4 Controller Programming 71 9 5 Preventing Hazardous Displays 71 Pavement Markings si in du SERIALS EGS sci ANA Css 73 10 1 General adar keria e elus aies AMENER LAS DER ess 73 10 2 Longitudinal Lines 73 10 2 1 Dividing Lines 73 10 2 2 AR ARS e rc vU 73 10 23 Turn lines guerre ree gen Re ren key n n Y Re ag ava CR RR g 73 10 3 Transverse lines 4434 oet edet dace tech tgo dede doen docto b dome 73 10 3 1 Stop WINGS zs sx oshk REGERE RES ei AC REEEAXGRANER ANGE RR RS 73 10 3 2 Pedestrian Crosswalk Lines 74 10 4 Painted Medians and Islands 74 10 5 Pavement Messages and Symbols 74 10 6 Raised Pavement Markers 74 AUSTROADS Accessed by AR M VICROADS on 02 Ju
147. curacy of target vehicle detection in relation to the detection function required also affects the loop width chosen Figure 8 2 shows different loop shapes namely a rect angular b symmetripole c quadrupole d slanted and e double diamond Figure 8 2 a shows various applications of the rectangular loop including its use in a single lane and across several lanes as well as a loop swung at an angle of approximately 20 degrees to the direction of vehicular travel which has been found to be effective in detecting cyclists this application can also be used for symmetripole and quadrupole loops Hulscher and Sims 1974 examined the relative merits of the various configurations with respect to sensitivity TRAFFIC DETECTION noise immunity interference and similar performance parameters The most common loop shape in use is symmetripole but some jurisdictions use a rectangular loop shape From electromagnetic considerations the optimum loop size for presence detectors are the vehicle dimensions However as vehicles vary in size a compromise is necessary To adequately detect small vehicles a loop size of ten square metres is considered a practical maximum The sensitivity of detection within and between lanes is also determined by the shape and size of the loop Length of the detection zone is not necessarily the same as the loop length due to fringing field effects as affected by the sensitivity settings of the d
148. d as a three aspect signal face the display sequence shall be Off to Green to Yellow to Red to Off Some jurisdictions use the sequence Off to Green to Yellow to Red to Green to Off The STOP HERE ON RED SIGNAL sign Section 11 3 2 shall be provided on the primary signal post if no stop line is marked b TZ Flashing signals The signal face containing flashing signals shall comprise a single steady yellow signal surmounted by twin alternate flashing red signals in the configuration shown in Figure 15 2 b The display sequence shall be Off to Yellow to Flashing Red to Off Signs shall be displayed at or near the signals indicating to road users that they must stop when the lights are flashing Signals shall be visible to all pedestrians and other road users on the approaches Activation of the signals is initiated manually within the emergency service facility and automatically displays the yellow signal for 4 to 6 s followed by the red or flashing red signal which then continues to operate until switched off 15 5 Public Transport Priority Special public transport priority treatments at signalised intersections such as special signal phases for buses and trams are used as a travel demand management measure to encourage the use of public transport Signal aspects and display sequences for buses and trams are described in Sections 5 2 and 5 10 Sections 8 5 1 and 8 5 2 discuss detection of buses and trams 15 5 1 Bus Priorit
149. d signals the phase green times therefore the cycle time are estimated average values ii Critical movement analysis results iii Cycle time or maximum green time optimisation results c Capacity i Saturation flow estimates including indications of any lane underutilisation and shared lanes that operate effectively as exclusive lanes de facto exclusive lanes ii Capacity and degree of saturation iii Practical spare capacity d Performance i Delay queue length average and percentile stop rate etc 138 ii Level of service iii Average speed including the effect of delay iv Operating cost fuel consumption and pollutant emissions carbon dioxide carbon monoxide etc D 3 Existing Geometry and Phasing D 3 1 Description and Input Data for Design 1 The current intersection layout Design 1 is shown in Figure D 1 The North South road Main Road has 3 lane approaches with median and clearway conditions whereas the East West road Side Street has 2 lane approaches without median and with parking allowed up to 50 m to the stop line All approaches have shared left turn and right turn lanes and all lanes have normal stop lines no slip lanes or continuous lanes AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 Signalised crossings exist in front of all intersection legs except South Other details such as lane widths grades kerb to kerb road widths electric supply pole ESP
150. d signs vi Determine detector locations and prepare controller program 8 9 vii Prepare the electrical design 12 viii Determine the need for signal coordination and accordingly 13 prepare coordination plans ix Prepare operational documentation necessary for the installation 14 commissioning and operation of the signals 1 10 Maintenance Maintenance of traffic signal equipment is essential for effective operation Integral components of an effective maintenance system are a speedy and accurate fault reporting b fast response time to reported faults c preventative maintenance and d lamp changing 1 11 Education and Enforcement It is essential that road users understand the meaning of signal displays When unfamiliar displays are first used in a locality the need for public education should be considered Regulations concerning traffic signal operations should be enforced to ensure correct responses from the public and to deter unsafe practices 1 12 Definitions Terms used in this guide are those commonly used and accepted in engineering practice Specialist terms are defined in the Glossary of Terms given at the start of this document also see AS 1348 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 2 Design Data 2 1 Introduction Design data are used to assess the adequacy of geo metric layouts the location of signal equipment the signal phasing and time settings These
151. data should be accurate and up to date Data can be divided into four main categories a physical layout b traffic data c crash data and d planning information concerning future developments Where data are estimated or predicted the effect of data accuracy levels on the design should also be considered 2 2 Physical Layout of Intersections The following features of the site should be shown on a base plan where relevant a b relevant property boundaries and building lines type and location of kerbs and channels c layout and condition of pavements medians etc on all approach and exit roads d approach grades e parking restrictions or facilities bus bays taxi zones f location of all poles and aerial cables note whether high voltage low voltage or telecommunication lines VS position type and size of existing road signs and any other roadside furniture g h location and nature of existing street lighting i position of any overhead obstructions horizontal and vertical clearances to verandahs signs power lines shop awnings etc should be shown location of trees and their probable size when fully grown k type and location of surrounding development residential suburban shopping industrial central business district railway stations schools etc I access to properties queuing vehicles may block acc
152. delay is experienced when a signal changes from red to green This delay includes allowance for the alertness of drivers perception and reaction time preparation of the vehicle selecting gear releasing hand brake and acceleration to the desired or possible speed see Appendices A and B There is also a safety element involved in determining the minimum green time since drivers expect the signal to remain green for a reasonable time and a green interval which is unduly short leads to erratic behaviour and rear end collisions Motor cycles and passenger cars have greater accele ration capabilities than trucks and in the interests of safety minimum green time should be related to the slowest vehicle likely to use the intersection within 95 per cent probability 5th percentile speed Minimum green time comprises the Basic Minimum Green Setting Section C 4 2 1 plus a variable time determined by the Increment and Maximum Variable Initial Green Settings Section C 4 2 2 The Basic Minimum Green Setting is the minimum time a green aspect can be displayed when stop line detectors are used When using only advance detectors the minimum green time is increased above this value in order to allow for vehicles stored between the stop line and advance detector location The Increment and Maximum Variable Initial Green settings are used for this purpose For stop line detectors the Maximum Variable Initial Green setting is zero A me
153. dents at Intersections Civil Engineering Thesis University of Melbourne MILLER A J 1968 Australian Road Capacity Guide Bulletin No 4 Australian Road Research Board Vermont South Australia reprinted as Research Report ARR 79 1978 superseded by Research Report ARR 123 NEGUS B J and MOORE S E 1984 Benefits of SCRAM the Maroondah Highway survey Proc ARRB 12th Conf 12 4 pp 1 16 ARRB Transport Research Ltd Vermont South Australia NRTC 1999 Australian Road Rules National Road Transport Commission Printed and distributed by the NSW Government Information Service Sydney New South Wales Australia OGDEN K W 1996 Human factors in traffic engineering In Traffic Engineering and Management Eds K W Ogden and S Y Taylor Institute of Transport Studies Department of Civil Engineering Monash University Melbourne Australia Reprinted 1999 pp 3 20 OLIVER J W H 1979 Skid Resistance Reduction in Wet Weather Due to Hydroplaning of Vehicle Tyres Pavement Surface Drainage Symposium Sydney May 1979 ARRB Transport Research Ltd Vermont South Australia PLINE J L Ed 1999 Traffic Engineering Handbook Prentice Hall Eaglewood Cliffs New Jersey U S A Fifth Edition QMR 2000 Road Planning and Design Manual Queensland Department of Main Roads Brisbane ROUPHAIL N M and AKGELIK R 1992 A preliminary model of queue interaction at signalised paired intersections Proc
154. design of signalised intersections Section 6 5 2 d Where regulations permit two aspect red yellow signal arrangements can be used to stop traffic at a signalised crossing on a left turn slip lane particularly if the slip lane is more than one lane wide see Section 5 3 4 Left turn islands for slip lanes should be designed to accommodate signal equipment the storage of pedestrians and the ends of any necessary stop line and signalised crossing or pedestrian Zebra crossing Figure 3 1 Painted five lane treatment on all approaches and high entry angle exclusive slip lane on East approach 10 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 3 3 Corner Kerb Radius Corner kerb radii and traffic islands should be designed to cater for the movement of design heavy vehicles Turning path templates are available to assist with the design of corner kerb radius and traffic islands See Design Vehicles and Turning Paths Austroads 1995 and Austroads GTEP Part 5 When applying turning path templates it should be remembered that under Australian Road Rules vehicles 7 5 m or longer including any load or projection legally can use up to two marked lanes to safely turn left or right The two marked lanes must be nearest to the far left of the road for left turns or nearest to the dividing line or median for right turns It is preferable to keep corner kerb radii to a minimum The use of l
155. diation especially under conditions of low ambient light levels the signal luminance of shape coded signals must be controlled more carefully than the circular signal and the resultant reduced intensity of such signals severely restricts the visibility range as compared to the circular signal A 3 3 Colour Perception Since the primary information of the signal is trans mitted as changes in colour the recognition of colour is an important consideration Two areas of particular significance in relation to traffic signal displays are colour vision defect and the effects of glare 110 About 8 per cent of males and approximately 0 4 per cent of females have some defect in discriminating colours involving the red and green receptor system A summary of the main types of colour vision defects in relation to traffic signals is given by Fisher and Cole 1974 In order to make allowance for the incidence of colour vision defects in the signal displays colour is specified within close limits and at maximum spectral separation This provides the optimum degree of colour discrimination for people who confuse the red and green colours Position coding of signals also assists In a vertically oriented system the red signal is therefore only displayed on the top and the green signal on the bottom see Section 5 In a horizontally oriented system e g for lane control the red signal is always on the right and the green signal on the left of the l
156. driver frustration This cannot be avoided in heavy traffic situations but delays can be reduced in low traffic situations by adding an all red phase The controller will normally wait in the all red phase until one of the other two phases is demanded That phase can then be introduced immediately with minimum delay to the motorist The phase is extended and terminated as usual Where guard fence is used on the single lane bridge approaches it should be extended if necessary to protect the traffic signal posts and controller 105 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 15 11 2 Portable Signals Portable traffic signals are intended primarily for short term application of single lane operation If conditions are to continue unchanged for longer than two or three months consideration should be given to the installation of temporary fixed rather than portable traffic signals see Section 15 11 71 Decision regarding this can be made on safety and economic grounds Portable traffic signals comprise a single column with three circle aspects and are usually trailer mounted or in tripod format One signal face is required to control each direction of travel This is located at or 6 m downstream of the stop line or stopping position on each approach A regulatory sign STOP HERE ON RED SIGNAL Section 17 3 2 is also erected adjacent to the stop line Requirements for the design construction and per formanc
157. dvance detector loops are located at a distance from the stop line that corresponds to the actuated signal gap setting Under free flow conditions AUSTROADS Figure 8 5 Use of queue loop for demanding a right turn phase 65 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS c use of roundabout metering signals to create gaps for roundabout legs with excessive queuing see Figure 15 3 in Section 15 7 where the main approach contributing to the circulating stream causing the queuing problem metered approach is stopped by a red signal when the queue reaches the advance queue loop on the controlling approach Ak elik Chung and Besley 1998 and d use of part time metering signals at sign controlled intersections to create gaps in major road traffic to reduce excessive delays experienced by vehicles on the sign controlled approach by stopping the major road traffic using a queue detector on the sign controlled approach Section 15 13 8 3 5 Operational Characteristics of Loop Detectors In previous sections only the principal characteristics of presence and passage detection have been discussed For satisfactory performance other operational para meters of loop detectors may need to be considered These include sensitivity paralysis time response delay and other factors that are beyond the scope of this guide Further details concerning operational require ments can be found
158. e Basic information necessary to promote uniformity in the design of traffic signal installations is provided in this guide Design practice signal equipment used and the signs and pavement markings that are uniquely associated with traffic signals are discussed The guide can generally be applied in situations where the speed limit is 80 km h or less When installed in locations where the speed limit is above 80 km h measures should be taken to ensure safe operation Although the guide may be applied to situations with higher traffic speeds allowance should be made for the fact that driver judgement and response are more critical and the possibility of unsafe operation is in creased in such situations It is emphasised that this is not a standards document The hierarchy of documents in relation to the use of this document is i Australian and New Zealand Standards ii Guide to Traffic Engineering Practice series and iii Local in house standards and manuals Any reference to right turn and left turn movements in this document is based on driving on the eft hand side of the road as applicable in Australia and New Zealand Any specification or recommendation related to these movements should be applied to driving on the right hand side of the road by interchanging the terms left turn and right turn 1 3 Statutory Provisions The installation of and compliance with traffic control devices are the subject of legislat
159. e A traffic management method for increasing capacity under conditions of high traffic demand and marked directional split by means of reversible lanes or carriageways Time Distance Diagram A graphical representation of the movement of a vehicle or traffic stream in terms of its time and distance coordinates e g used to show signal coordination along a route or for showing vehicles queuing at traffic signals Time Occupancy Ratio The proportion of time in a given period when the passage or occupancy detector at a point along the road is occupied by vehicles xxiv Timing Plan A plan that defines the cycle time green splits and offsets for each intersection in a coordinated signal system Traffic Movement of vehicles and pedestrians people and goods along a route Traffic Actuated Control A control method that allows a variable sequence and variable duration of signal displays depending on vehicle and pedestrian traffic demands All vehicle movements phases are actuated in Fully Actuated Control in contrast with Semi Actuated Control where only minor vehicle movements e g side road traffic are actuated Traffic Composition The proportions usually expressed as a percentage of the different vehicle classes and turning vehicles within the total traffic flow Traffic Control Device Any traffic sign road marking traffic signal or other device placed or erected under public authority for the purpose of reg
160. e Figures C 2 and C 3 C 5 1 Pedestrian Walk Time The purpose of the Walk Time Setting is to give pedestrians sufficient time to begin their crossing This setting determines the duration of the green Walk display Its value depends on the amount and type of pedestrians using the crossing Table C 2 indicates that typical Pedestrian Walk Times used in practice are in the range 5 to 16 seconds Pedestrian Walk Times can be determined as follows a Use a minimum value of 5 seconds However where the signalised crossing is on a very narrow carriageway such as a slip lane a minimum of 4 seconds is permissible b Add 2 seconds for each additional rank of pedestrians waiting optional TZ c Allow more time for i schools ii railway stations iii elderly children and people with disabilities and iv crossing of wide roads in one movement i e beyond medians When crossing a wide road with median in one move ment the Walk Time may be calculated from b Led Veg C 5 1 subject to t 5 where tow pedestrian Walk Time s Low pedestrian walking distance m determined as the larger of the first carriageway width plus median width measured in each direction and Vow pedestrian walking speed m s When Walk Time is determined using Equation C 5 1 the calculation of clearance distance is based on the larger of the two carriageway widths i e excluding the median width as disc
161. e Section 11 3 5 Illuminated signs may apply continuously or at certain limited times during the day They may flash con tinuously or for that part of the signal cycle when emphasis is required 11 3 Signs at Signal Installations 11 3 1 Parking Signs Signs controlling or prohibiting parking or stopping are used extensively in the vicinity of signalised inter sections in order to improve intersection capacity and to reinforce statutory no stopping requirements assoc iated with traffic signals see R5 series signs in AS 1742 Parts 1 and 11 See Section 3 6 1 on parking control 11 3 2 STOP HERE ON RED SIGNAL ARROW Signs The STOP HERE ON RED SIGNAL and STOP HERE ON RED ARROW signs R6 6 and R6 14 shown in Figure 11 1 are not intended for routine use at signalised intersections Uses to which it may be put are generally limited to the following Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS a To define a stopping point which is different from the location of the primary signal and where the stopping point cannot be adequately defined by a stop line b TZ In situations where traffic turning with a green signal is required to stop at a red signal in the cross street e g internal approaches of staggered T intersections or within a wide median opening where right turn traffic filtering through an opposing stream is not safe c As a reinforcement in situations where signals might be unexp
162. e and pedestrian movements at signalised intersections are shown in Figure C 2 Pedestrian and vehicle phase intervals at a midblock Pelican crossing are shown in Figure C 3 see Section 6 5 3 Pedestrian displays are Walk Flashing Don t Walk and Steady Don t Walk The Flashing Don t Walk display corresponds to Clearance Intervals 1 and 2 The Clearance 2 interval overlaps with part of the vehicle clearance interval The Pedestrian Delay interval shown in Figure C 2 pro vides a delay between the push button actuation and the placement of the pedestrian demand Section C 5 3 125 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Figure C 2 Definition of pedestrian movement phase intervals and relationship with parallel vehicle movement intervals where applicable Start of Start of End of pedestrian pedestrian pedestrian Pedestrian movement movement clearance movement Pedestrian Placement of push button pedestrian operation demand Total clearance time Pedestrian Delay Clearance 1 Steady Don t Walk Green Flashing Don t Steady Don t Walk Red Walk Red Walk Red Start of Phase change Endlos Phase point Phase Vehicle Movement Vehicle Green Running Intervals Vehicle Intergreen Clearance Intervals Vehicle All Red Applicable for parallel vehicle pedestrian movements at intersections Vehicle Yellow
163. e arranged to achieve a better grouping of the intersections with similar cycle times as far as the network geometry permits For an overall benefit to be derived from signal coordination the benefit from progressions must exceed the disbenefit from the operation of some intersections at a higher than required cycle time Wherever possible measures should be taken to decrease the cycle time requirement of the critical intersection so as to improve the performance of traffic not only at the critical inter section but also in the control area as a whole Since all intersections in the area are to operate with the common system cycle time the green splits for each intersection are calculated using this cycle time except in the case of double cycling An offset is the difference between the beginning or end times of the green periods at the given intersection and aselected reference intersection i e it is the time difference between phase introductions or terminations Accordingly offsets can take positive or negative values For example in Figure 13 7 a Intersection 1 is the reference intersection offset O 0 and Inter sections 2 3 and 4 have positive offset values O5 O3 O gt 0 In Figures 13 1 b and c Intersection 3 is the reference intersection offset O 0 Intersection 4 has a positive offset value O gt 0 and Intersections 1 and 2 have negative offset values O4 O lt 0 The reference intersec
164. e deg E uu etd a ee 62 8 3 1 Detector Types ss 4suse ak Rete Rd Reb ee dan ad dame 62 8 3 2 Detection System Functions 62 8 3 3 Loop Shape and Size seose sde sata dan Gee e eed tr a rede 62 8 3 4 Location of Detectors 64 8 3 5 Operational Characteristics of Loop Detectors 66 8 4 Pedestrian Traffic Demands 66 8 4 1 Pedestrian Detection 66 8 4 2 Automatic Introduction of Pedestrian Movements 66 8 4 3 Push Button Location 66 8 5 Special Traffic Detection 67 8 5 1 BUSES aede nre dre terres er er re ire ee RR Re No ee o Wer 67 8 5 2 lcu eL 67 8 5 3 Bicycles cox cese Sd a UN torso edet 67 8 5 4 Emergency Vehicles 68 8 5 5 Emergency Service Demand 68 8 5 6 Railway Traffic 68 Signal Controllers 69 9 1 GSS Ta ae od e gei bed dime tein enne Ge RERUM NIAE 69 9 2 Types Of Control 5eme tae artubus dta arundo 69 9 2 1 Traffic Actuated Control 69 9 2 2 SCATS Master Isolated Control 69 9 2 3 Semi A
165. e following examples a Where the warning or stopping function of primary or dual primary lanterns is adversely affected on left hand curve approaches an additional lantern should be provided on the right hand side of the road b Where it is not practicable to screen a lantern effectively from traffic for which the signal display is not intended see Section 4 2 2 that lantern should be relocated or omitted Where it is necessary to prevent a lantern from being seen by traffic at an upstream stop line tilting of the lantern or other measures to limit the field of view can provide effective solutions Some agencies tilt only the green face display as the confusion normally only occurs when green is displayed c d Where a railway line is in close proximity to a signal installation lantern screening and aiming arrangements must ensure that signals do not constitute a source of confusion to train drivers see Section 15 3 4 Where a low bridge over an approach roadway obstructs visibility of the lanterns an advance warning sign may be used see Figure 15 1 When the bridge is adjacent to the intersection an additional primary signal may be placed in advance of the bridge not more than 10 m from the stop line e AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 7 5 8 Other Street Furniture To reduce street furniture clutter suitably located existing utility poles may be
166. e forced to stop intermittently In this case this phasing operates as a metering device The use of a repeat right turn phase introduces an additional intergreen period that may impact the efficiency of the intersection if the right turn is a critical movement 6 4 Left Turn Movements Left turn movements do not control phasing selection They can run in one or more phases depending on phasing requirements for other movements When controlled by circular signals alone left turning traffic will filter through gaps in the parallel pedestrian traffic during the green and intergreen periods Red left turn arrows may be used where this practice is considered unsafe due to an unacceptable accident history or where the following conditions contribute to an increased risk of accident a the volume of left turn traffic is high or b the speed of left turn traffic is high due to the turn geometry or c the visibility of pedestrians by turning vehicles is inadequate AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 SIGNAL PHASING Figure 6 6 Examples of complementary left and right arrow controlled turns J m m An example of the use of left turn red arrow is holding the left turn movement on red during pedestrian Walk and or Clearance intervals The red left turn arrow can also be used to provide priority for special vehicle move ments e g train or tram level crossings Figures 5 12 and 5 14 in
167. e introduced according to a weekly schedule or timetable Each plan defines the cycle time green splits and offsets to be used for the duration of the plan Depending on the complexity and variation of traffic demand patterns between three and ten plans are usually provided typically for the morning and evening peak periods business hours late night traffic and weekends Signal timing plans are calculated off line using manual or computerised methods Fixed time control does not rely on data from vehicle detectors although some variants include a degree of local traffic actuation that requires the use of detectors Fixed time systems offer the advantage of relative simplicity of both equipment and control philosophy On the other hand they are unable to cope with unpredicted traffic conditions Furthermore as traffic conditions change in time signal plans become inappro priate aged This requires collection and processing of large amounts of data for updating of signal timing plans Deferral of the development of new timing plans or introduction of ad hoc changes to the plans and timetables result in sub optimal traffic performance 13 5 2 Traffic Responsive Plan Selection System This system selects predetermined signal timing plans using algorithms that respond to changing traffic conditions based on data collected from detectors The simplest form of traffic responsive operation is based on pattern matching In this method
168. e of portable traffic signal systems are specified in AS 4191 Location and operation of portable traffic signals is described in AS 1742 Part 3 15 12 Left Turn On Red A LEFT TURN ON RED PERMITTED AFTER STOPPING LTOR sign Figure 11 9 allows vehicles on the signed signalised intersection approach to turn left when facing a red circle display subject to having first stopped at the stop line on that approach then proceeding only if it is safe to do so Location of the LTOR sign is discussed in Section 11 3 8 LTOR may be used as a delay reduction measure subject to any jurisdictional regulations and the criteria described in the Australian Standard AS 1742 Part 14 to ensure the safety of pedestrians cyclists and motorists LTOR may be considered for use where the left turn movement is controlled by circular aspects only In addition to the conditions for use specified in AS 1742 Part 14 LTOR is not permitted on any approach where the LTOR movement would conflict with a bus or tram movement proceeding on a white display The loop detectors in the left lane where LTOR is used will need to be presence timed to zero to ensure that a 106 vehicle having turned from the lane during the red period does not unnecessarily initiate a phase change Slip lanes should not be provided with LTOR signs as other road rules apply to this situation 15 13 Metering Signals at Sign Controlled Intersections The use of metering signals at i
169. e requirements of AS 2276 are used For reasons of aesthetics and operational benefits cables are installed underground Multicore cables have core insulation based on a four colour system as follows a Earth core Green Yellow b Neutral core Black c ELV return Grey d Other numbered cores White Installation techniques will depend on local practice and policies The common bus system or the radial routing system are two techniques used It should be noted that the conductor sizes of multi core cables are defined by AS 2276 Part 1 For long cable lengths or high electrical loading conditions calculations of voltage drop and current carrying cap acity may indicate that larger conductors are required The number of circuits required will determine the number of cores required in each cable Provision must be made for i one active cable core for each colour of each signal group ii one cable core for each pedestrian push button demand circuit and iii a number of spare cores Spare cores allow for modifications to the signal control mode without recabling In the event of core damage it may allow repair to be carried out without the need to replace the cable Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 12 4 Vehicle Loop Detector Cables For vehicle loop detector sensors either post mounted or located in the controller housing the feed to the loops should be by screened feeder cable
170. e to operate as efficiently as possible AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 INTRODUCTION Figure 1 1 Traffic signal external factors General community Trip generation Expectation of travel conditions route selection information e Information e Public policies Transportation Regulations Reports requirements Restrictions Suggestions Non road based transport Y Traffic authorities Road user requirements Measures of Design Road signal system Settings Driver characteristics performance Vehicle Signal system Vehicle and pedestrian signal displays Road users Environmental variables Observance levels e Weather Enforcement levels Time of day Road conditions e User characteristics Traffic movements Accident rates AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Table 1 1 Signalised intersection design process Design Tasks Section i Collect design data 2 ii Determine the geometric requirements 3 iii Determine signal phasing and time settings 6 App B C This involves determining capacities and traffic performance characteristics for a number of possible phasing schemes and geometric layouts iv Determine signal face layouts 5 v Select signal hardware determining location of signal displays 4 7 10 11 and appropriate use of pavement markings an
171. ecified by the type of master control system to be installed Detector placement and function options include individual lane detectors approach detectors stop line detectors advance detectors or queue detectors see Section 8 Cycle and Phase Timing Determination of a common system cycle time and phase green times is discussed in Section 13 2 1 Phasing Design The phasing design of signals needs to consider the coordination requirements see Section 6 For example it may be necessary to vary the phase sequence to achieve two way coordination and this may not be apparent until the system progression strategy has been determined Some isolated signal features such as conditional pedestrian movements can irregularly interrupt associated traffic movements and impair progres sion or capacity These features should be removed by redesign of the intersection phasing Side Road and Pedestrian Delay At intersections in a coordinated system there could be an increase in delays to vehicles entering from side roads and pedestrians crossing the main route compared with operation on an isolated traffic actuated basis due to a longer cycle time imposed by the critical intersection in the system Therefore careful consideration must be given to this factor to ensure minimisation of this adverse effect e g through sub area optimisation in order to reduce the cycle time Public Transport The needs of public transport should be c
172. ected such as at temporary signals Section 15 11 Figure 11 1 STOP HERE ON RED SIGNAL R6 6 and STOP HERE ON RED ARROW R6 14 signs STOP HERE STOP HERE ON RED ARROW ON RED SIGNAL J entered In this situation turning vehicle drivers may assume there is no crossing and may become unaware of pedestrians The sign should only be used in the above circum stances Indiscriminate use would reduce the effective ness of the sign and the traffic regulation that requires drivers to give way to pedestrians crossing the road drivers are entering Generally this sign is erected on the same traffic signal posts as the signal faces which control the movement Internally illuminated or fibre optic GIVE WAY TO PEDESTRIANS signs that are activated by pedestrian demand may be used for greater conspicuity 11 3 3 GIVE WAY TO PEDESTRIANS Sign The GIVE WAY TO PEDESTRIANS sign R2 10 shown in Figure 11 2 is used at signalised intersections under following circumstances a Turning vehicles are observed not to give way to pedestrians using a signalised crossing This may occur with filter right turn movements through a parallel pedestrian movement where the signalised crossing distance is long In this case the right turn movement may become established before a pedestrian enters the conflict zone particularly from the same side of the road that the right turn commences b TZ Turning traff
173. ected through a transponder transmitter fitted to the vehicle The appropriate authority provides the necessary advance warning of the approach of the vehicle and special arrangements are made to ensure their prompt passage When emergency vehicle demands are recorded by a controller existing displays are terminated safely and 68 a special priority traffic phase is introduced and main tained until the demand is removed 8 5 5 Emergency Service Demand Emergency service demands are normally recorded by push buttons Typical applications involve signals in close proximity to fire stations and ambulance depots The emergency service may require a green movement of fixed duration within a fixed time of the demand being made or they may be prepared to wait for the required movement and move off when indicated by the control equipment 8 5 6 Railway Traffic Where railway level crossing signals are coordinated with road traffic signals the usual sequence of oper ations is as follows see Section 15 3 i traffic queued across the line is cleared ii vehicles crossing the railway line are stopped and iii if the intersection signals have not reached a safe display by the time railway signals begin to operate then the intersection signals are switched to flashing yellow The precise method of operation required should be obtained from the local rail authority Common inputs from the level crossing control equip ment are
174. ections OR b TZ For each of eight one hour periods of an average day the pedestrian flow crossing the road exceeds 175 ped h and the vehicular flow exceeds 600 veh h in both directions or where there is a central pedestrian refuge at least 1 2 m wide the major road flow exceeds 1000 veh h in both directions and there is no other pedestrian Zebra crossing or signalised crossing within a reasonable distance OR Where the crossing is used predominantly by children and for each of two one hour periods of an average day the pedestrian flow exceeds 50 ped h and the vehicular flow exceeds 600 veh h in both directions OR c d Where at least 50 per cent of pedestrians using the crossing are elderly or handicapped persons and for each of two one hour periods of an average day the pedestrian flow exceeds 50 ped h and the vehicular flow exceeds 600 veh h in both directions OR A midblock signalised crossing may also be considered in special situations if one of the following warrants is met e i The location has been the site of two or more pedestrian casualties over a three year period where these could have been prevented by a midblock signalised crossing OR ii There is a large seasonal variation in the vehicular traffic flow such as at a holiday resort and it can be shown to meet the general criteria during the busy season even if during the rest of the year the general cri
175. ed during Phase B providing 300 mm signals ii North approach Four signal faces primary d Use of Mast Arm dual primary secondary and tertiary are provided The primary and tertiary signal faces are three aspect circles The dual primary and secondary signal faces are six aspect with three aspect circles and three aspect arrows As the medians are of sufficient width these signal faces are on posts located in the medians The green e arrow is displayed in Phase C only The green circle is displayed in both A and C phases and the C A intergreen The use of mast arm or overhead signal faces is not warranted at this site For the South and North approaches the dual primary signal face can be accommodated on the median islands as its width is greater than the 1 5 m recommended for dual column aspects of 200 mm size Target Boards All vehicle signal faces are provided with a target board appropriate to the signals being used f Visors and Louvres iii South approach Four signal faces primary dual primary secondary and tertiary are Closed visors are to be provided on all secondary provided As the medians are of sufficient and tertiary signal faces except the three aspect width these signal faces are on posts located right arrow signal faces see Section 7 6 The in the medians All signal faces are three use of louvres is not warranted in this case aspect circles The green circle is displayed g Locati
176. ed for Traffic and Pedestrian Control Lanterns Research Report ARR No 38 ARRB Transport Research Ltd Vermont South Australia STANDARDS AUSTRALIA 1996 Manual of Uniform Traffic Control Devices Part 14 Traffic Signals AS 1742 14 Standards Australia Sydney STANDARDS AUSTRALIA 175 2000 Sydney For online search http www standards com au AS 1100 401 1984 Technical drawing Engineering Survey and Engineering Survey Design Drawing AS 1158 1986 1999 Road Lighting AS 1348 1986 1992 Road and Traffic Engineering Glossary of Terms 156 AS NZS 1428 4 1992 Design for Access and Mobility Tactile ground surface indicators for the orientation of people with vision impairment AS 1580 1992 2000 Paints and Related Materials AS 1742 1990 2000 Manual of Uniform Traffic Control Devices AS 1743 1992 1995 Road Signs AS 1744 1975 Forms of Letters and Numerals for Road Signs AS 1798 1992 Lighting Poles and Bracket Arms AS 1906 1981 1997 Retroreflective Materials and Devices for Road Traffic Control Purposes Glass Beads for Road Marking Materials AS 2009 1991 AS NZS 2053 1995 1997 AS 2144 1995 AS NZS 2276 1992 1998 AS 2339 1997 Conduits and Fittings for Electrical Installations Traffic Signal Lanterns Cables for Traffic Signal Installations Traffic Signal Posts and Attachments Pedestrian Push Button Assemblies AS 2353 1999 AS 2578 1983
177. ed movements number of approach and exit lanes at the stop line median width at the stop line if a median strip exists approach grade negative for downhill positive for uphill upstream and downstream short lanes any turn bans busonly or tram only lanes details of parking restrictions bus stops tram stops emergency access Accessed by AR M VICROADS on 02 Jun 2005 iii For each approach lane lane type including slip lane continuous lane short lane due to turn slot or parking lane discipline left turn through right turn exclusive or shared lane width lane storage length free non blocking queue values for shared lanes basic saturation flow e number of parking manoeuvres and buses stopping affecting saturation flow b Volume Data i Demand volume counts or estimates in vehicles per 15 minutes 30 minutes or 60 minutes in origin destination format describing left turn through and right turn movements as well as any diagonal movements or U turns ii Heavy vehicle data for each movement iii The method of counting heavy vehicles HVs percentage HVs separate light and heavy vehicles or HVs included in the total count iv Pedestrian volume counts Z Peak flow factors for peaking effects and flow scales for design life analyses v c Signal Control Data i Actuated or fixed time analysis ii Signal phase seque
178. ed position to a final speed of 60 km h For a heavy vehicle with a power to weight ratio of 12 the model indicates an average acceleration rate of 0 8 m s and a corresponding maximum acceleration rate of 1 4 m s for acceleration from stopped position to a final speed of 60 km h 113 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS B 3 Basic Properties of Vehicular Traffic B 3 1 General Various traffic characteristics are used to describe collective behaviour of vehicles in traffic hence referred to as traffic flow parameters Knowledge of relation ships among traffic flow parameters is useful for traffic signal control purposes as discussed in Section 8 1 in relation to traffic detection The basic parameters describing traffic flow character istics can be summarised as follows i distance based traffic flow parameters spacing Ly space gap length L vehicle length L ii time based traffic flow parameters headway h vehicle passage time t gap time t occupancy time t space time t and iii other traffic flow parameters derived from the time based and distance based parameters speed v flow rate q density k time occupancy ratio O and space occupancy ratio O Average values of the above parameters are considered when representing aggregate characteristics of traffic streams The parameters are explained in Sections B 3 2 and B 3 3 For further information ref
179. eduction in the friction coefficient occurs with wet pavements Oliver 1979 a situation that is not always realised by drivers since the friction charac teristics of a pavement surface are not apparent from its appearance particularly where polishing of the aggregate has occurred Data given in Glauz and Harwood 1999 indicates that appropriate friction coefficients for cars on wet surfaces are in the range 0 28 to 0 40 corresponding to deceleration rates in the range 2 7 to 3 9 m s2 Glauz and Harwood 1999 suggest that deceleration rates up to 3 0 m s are comfortable for passenger car occupants and suggests this value for determining yellow time at signals see Appendix C Section C 4 6 1 AUSTROADS APPENDIX B VEHICULAR TRAFFIC FACTORS In terms of deceleration characteristics for normal operational analysis maximum deceleration rates of 1 7 m s for cars 1 5 m s for light trucks and 1 2 m s for heavy trucks were observed during deceleration manoeuvres at signalised intersections roundabouts and priority intersections in urban areas in New Zealand Dibley and Reid 1990 The deceleration model for normal operating conditions for light vehicles at intersections described in Ak elik amp Associates 2001a indicates an average deceleration rate of 1 8 m s and a corresponding maximum deceleration rate of 3 1 m s for stopping from an initial speed of 60 km h For a heavy vehicle with a power to weight ratio of 12 the
180. een time only for the cyclists effectively providing an early cut off Since this reduces the bicycle green time it should be ensured that the combined green plus intergreen time is sufficient for a cyclist accelerating from rest at the stop line to clear the controlled area ii Allowing the cyclists to move off before the vehicle traffic late start This is appropriate where the bicycle lane does not continue through the inter section and bicycles have to merge with other traffic 135 Accessed by AR M VICROADS on 02 Jun 2005 Appendix D Worked Example D 1 Introduction This appendix presents a worked example to illustrate various aspects of signalised intersection timing perfor mance analysis and implementation procedures for a signalised intersection design A four way intersection controlled by actuated signals is considered Under current conditions Design 1 a two phase system is used which is inadequate due to filter right turn movements against heavy opposing through flows As a result improvements to the intersection geometry and signal phasing are considered Design 2 Signal timing and performance analyses presented in this section were carried out using the aaSIDRA soft ware package Akcelik amp Associates 2001a The aim is to ensure that the model replicates the observed conditions for current Design 1 and then to see that the proposed Design 2 provides satisfactory operating performance The anal
181. een the two intersections internal approaches Typical examples are staggered T intersections and freeway diamond interchanges as seen in Figures 15 6 a and b Inter sections with a wide median have similar characteristics Paired intersections are regulated either by a single traffic signal controller using built in offset arrange ments achieved through special phasing arrangements or by two separate signal controllers that are linked under a signal coordination system With paired intersections care should be taken to avoid the potential see through problem i e downstream green signals being seen by motorists stopped at the upstream stop line see Section 7 5 7 SPECIAL APPLICATIONS AND FACILITIES Severe unequal lane utilisation may be observed due to heavy origin destination flows in paired intersection systems e g dog leg movements at staggered T intersections This should be taken into account in designing geometry and signal phasing for paired intersections Management of queuing in internal approaches of a paired intersection system is important to avoid block age of upstream signals by through and turning vehicles queued in internal approach lanes Early cut off and early start phasing arrangements simultaneous offsets Section 13 2 2 and shorter signal cycle times are useful methods for this purpose see Appendix C It is important to ensure that adequate queue storage spaces are provided for vehicles tur
182. eith VicRoads Geoff Horni Department of Infrastrtucture Planning and Environment Northern Territory Geoff Lake Roads and Traffic Authority New South Wales John Buckland Transport South Australia Jon Douglas Queensland Department of Main Roads Ken Grattan Department of Infrastrtucture Planning and Environment Northern Territory Martin Chelini VicRoads Michael Day Department of Urban Services Australian Capital Territory Peter Freeman Department of Infrastructure Environment and Resources Tasmania Peter Lowrie Roads and Traffic Authority New South Wales Ross Thomson New Zealand Published by Austroads Incorporated Level 9 Robell House 287 Elizabeth Street Sydney NSW 2000 Australia Phone 61 2 9264 7088 Fax 61 2 9264 1657 Email austroads austroads com au www austroads com au Reproduction of extracts from this publication may be made subject to due acknowledgement of the source Austroads believes this publication to be correct at the time of printing and does not accept responsibility for any consequences arising from the use of information herein Readers should rely on their own skill and judgement to apply information to particular issues Guide to Traffic Engineering Practice Traffic Signals THIRD EDITION Accessed by AR M VICROADS on 02 Jun 2005 Austroads Profile Austroads is the association of Australian and New Zealand road transport and traffic authorities whose purpose is to c
183. en Setting maximum green time minimum green time The following formula provides a simple manual method for determining the Maximum Extension Green Setting Ak elik 1995b Appendix B Geomax ly Rmax x yl Gmin C 4 1 where Gomax maximum Extension Green Setting s mi minimum green time Basic Minimum Green Setting with stop line detectors s y flow ratio demand flow rate saturation flow rate for the critical lane Rmax maximum red time that is acceptable to drivers e g 60 seconds and Xp practical degree of saturation maximum value acceptable at high demand conditions e g xy 0 95 AUSTROADS APPENDIX C SIGNAL TIMINGS C 4 4 Gap Setting The Gap Setting is used to set the maximum allowable time between successive detector actuations before the movement terminates due to large gaps between vehicles If the Gap Setting is too short the phase may terminate before a platoon of vehicles is passed and if it is too long the phase will extend unduly Microprocessor based controllers provide for at least 2 and up to 8 gap timers so that different approach char acteristics such as grade and turning radius can be catered for The Gap Setting is determined as a space time value measured between consecutive vehicles by the detector i e as the time when the detector is not occupied Table C 2 indicates that typical Gap Settings used in Australian practice are in the range 2 5 to 4 0 se
184. entation Table 7 2 shows the coverage provided by a lantern for various aiming distances 57 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS b TZ Table 7 3 lists the recommended aiming distances from the stop line towards the centre of the approach lanes for stopping and for warning functions c Starting signals should be aimed at a point 3 metres from the stop line at the centre of the approach d Manoeuvring signals should be aimed at the centre of the stop line e A lantern should not be required to be seen from closer than 8 m Table 7 2 Visual coverage of lanterns Visual Coverage Aiming Distance Ground Mounted Overhead metres from lantern metres from lantern 40 10 70 60 25 95 80 40 120 50 110 100 55 145 65 140 120 75 170 130 90 170 140 105 195 150 125 225 Approach Stopping Warning Speed km h metres from stop line 40 40 80 50 60 100 60 80 130 70 100 150 80 120 170 58 7 5 7 Modification for Unusual Geometry and Other Physical Considerations Alternative positions and or additional lanterns may be provided where fixed obstructions such as poles trees awnings underground services and background interference including illuminated advertising signs or the intersection approach geometry are such that standard positions and numbers of lanterns are not adequate to carry out the required functions These are illustrated in th
185. ents within the controlled area during which only red aspects are illuminated for conflicting movements Approach That section of road consisting of one or more lanes used by vehicles approaching an intersection or mid block site Approach Speed see Speed Area Traffic Control System see Wide Area Control System Arrow Aspect A masked vehicle aspect that displays an arrow shape when illuminated Arrow Controlled Turn A left turn or right turn movement at a signalised intersection that is made with a green arrow display and therefore is unopposed Also see Unopposed Turn Full Control Partial Control Arrow Mask A mask placed over a vehicle aspect so that an arrow shape will be displayed when the aspect is illuminated Also see Symbolic Mask Arterial Demand A feature of traffic signal controllers whereby a perma nent demand is placed for a particular phase or signal group Also see Recall Feature Arterial Road A road that predominantly carries through traffic from one region to another forming principal avenues of travel for traffic movements Aspect A single optical system circular arrow or symbolic on a signal face capable of being illuminated at a given time Red yellow green and white aspects are used for vehicle movements Also see Pedestrian Aspects Bicycle Aspect Special Vehicle Aspects Lantern Availability A measure of the probability in signal maintenance that the equipment will be
186. er to Akcelik Besley and Roper 1999 and Akcelik Roper and Besley 1999 B 3 2 Basic Parameters This section discusses all parameters listed in Section B 3 1 except flow rate density and occupancy ratios which are discussed in Section B 3 3 Figure B 1 gives a simple diagram that summarises the relationships among basic traffic parameters See Figure 8 1 in Section 8 for a diagram showing parameters relevant to the measurement of traffic parameters by presence detection Spacing is the distance between the front ends of two successive vehicles in the same traffic lane Space gap length is the following distance between two successive vehicles as measured between the rear end of one vehicle and the front end of the next vehicle in the same traffic lane spacing less vehicle length Headway is the time corresponding to spacing i e time between passage of the front leading ends of two successive vehicles h t t in Figure B 1 114 Vehicle passage time is the time between the passage of the front and back ends of a vehicle from a given point along the road Gap time is the time between the passage of the rear end of one vehicle and the front end of the next vehicle measured at a given point along the road and is equivalent to headway time less vehicle passage time Occupancy time starts when the front of a vehicle enters the detection zone and finishes when the back of the vehicle exits the detection zone Thus
187. ere it is safe to do so the arrow controlled right turn can be allowed to filter through the opposing through movement during the following phase the right turn movement from the West approach in Phase B in Figure 6 4 If filtering causes safety problems this right turn must be stopped using a red arrow display when the opposing through movement is operating full control Where the leading right turn movement is allowed to filter during the following phase in the case of six aspect signal face the arrow controlled turn must be terminated and held on a red arrow display at the beginning of the green circular display at the start of Phase B in Figure 6 4 The red arrow is then extin guished for the remainder of the green circular display red arrow drop out This phasing system becomes inefficient for shared lanes when a through vehicle calls the right turn phase and there are no right turn vehicles during that phase The provision of an exclusive right turn lane turn bay or full length lane is recommended 42 6 3 3 Lagging Right Turn Phasing A lagging trailing right turn sequence is where a right turn phase follows the phase in which the opposing through movement runs see Figures 6 7 and 6 5 In Figure 6 5 the lagging right turn movement from the West approach runs in Phase B and the opposing through movement from the East approach runs in Phase A A lagging right turn phase is controlled by three aspect right t
188. erminal assemblies provide for the connection of the cable to the signal equipment see AS 2276 Part 1 The signal cable provides 240 volt nominal 50 Hz power to the signal lanterns and circuits for pedestrian push buttons and other traffic demands This is a low voltage installation and must be installed to require ments of the local electricity authority and AS 3000 Part 1 4 2 5 Signal Controller The traffic signal controller regulates the sequence and duration of signal displays see AS 2578 Part 1 The main features of this equipment include a power switches for the signal lanterns b TZ failsafe systems to prevent conflicting signal displays c d vehicle detector systems provision for inputs from pedestrian push buttons or any other device lt e a logic unit to control the sequence and timing of movements or phases including minimum greens and safe clearance periods between conflicting movements f facilities for traffic personnel to monitor and alter its operation and facilities to allow data communications between the controller and a master control computer VS g 4 2 6 Traffic Detection The most common form of vehicle detector for most traffic control applications is the inductive loop AS 2703 Several turns of wire are placed in a slot cut in the road pavement AS 2276 Parts 2 and 3 The wire is connected via a feed cable to a detector sensor uni
189. erse a point or uniform segment of a lane or roadway during a specified time period under given roadway geometric traffic environmental and control conditions usually expressed as vehicles per hour passenger cars per hour or persons per hour Channelisation A system of controlling traffic by the introduction of a traffic island or median or markings on a carriageway to direct traffic into predetermined paths usually at an intersection or junction Clearance Time Time given to allow a terminating movement of vehicles or pedestrians to vacate the controlled area before the beginning of the next movement of traffic Also see Pedestrian Clearance Period Column of Aspects A combination of signal aspects arranged in a vertical assembly Conflicting Movements The vehicle or pedestrian traffic streams at an inter section whose paths cross or merge when moving simultaneously Controlled Area That portion of a carriageway or intersection the entry into which is controlled by traffic signals Controller The equipment including the housing that switches power to signal lanterns and controls the duration and sequence of signal displays xvi Controller Algorithm Programmed logic sequence internal to the controller which transforms operator input and traffic demands into traffic control signal sequences Controller Personality A unique program that configures the controller to the specific operational design of
190. es may be used as discussed in Section 5 3 4 Single aspect signals are not permissible except for overhead lane control signals as discussed in Section 15 10 Figure 5 3 Basic three aspect signal face layout eee f no column contains more than three aspects VS only one aspect of each colour is permitted in each column g h at one time not more than one aspect is illuminated in each column The use of three columns in a display is not recom mended as they are difficult to comprehend and are not catered for in standard mountings Therefore where possible they should be split into separate two column displays mounted on different posts or mast arms Multi column display sequences are discussed in Section 5 7 2 5 3 2 Multi Column Signal Face Layouts Multi column signal faces can contain four five or six aspects Generally these face layouts have an arrow aspect column adjacent to the basic three aspect column Section 5 3 1 Six aspect face layouts as shown in Figure 5 4 are used to control left turn or right turn movements independently of the through movement on the same approach Multi column signal faces shall comply with the following a aspects of the same shape and orientation are located in the same column b left turn arrow aspects are located to the left of the circular aspects and right turn arrow aspects are located to the right of the circular aspects c co
191. ess and detector position may be affected m location and size of drainage pits and pipes n the position of telecommunication sewer gas water and any other underground services these locations should be verified with the relevant authorities The following information should be noted for use in the design i work proposed by other authorities ii constraints on locations of controller and power supply posts intersection signalised crossings and pedestrian Zebra crossings cable ducts junction pits for ducting iii any special traffic which uses the intersection e g over dimensional vehicles special pedestrian needs and iv strategic location within the road network 2 3 Traffic Data Traffic demand volumes are essential for the design of traffic signal installations The design should place emphasis on serving transport needs of people and goods rather than vehicles only Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Traffic signals should operate efficiently over a wide variety of traffic conditions While designs are based on peak traffic conditions efficient operations at peak and lower volumes are provided by the use of adaptive control It is usually necessary to provide for a number of peak traffic conditions e g am and pm commuter retail recreation and special event peaks Local policies and consideration of demand flow patterns determine the
192. essure detectors Detector Loop One or more loops of wire embedded in the road surface and connected to the controller energised by a low voltage current The inductance of the circuit changes when a vehicle passes over the loop which is detected by a unit in the controller Diamond Overlap Phasing Phasing that allows right turns from opposing directions to operate either simultaneously or independently with the through movement on the same approach dep ending on demand for the right turns and conflicting through movements AUSTROADS GLOSSARY Display A signal aspect that is illuminated Display Sequence The order in which traffic signal displays occur Also see Phase Sequence Divided Road A road with a median that separates the opposing directions of travel Dividing Line A road marking formed by a line or two parallel lines whether broken or continuous designed to indicate the parts of the road to be used by vehicles travelling in opposite directions Dividing Strip An area or structure that divides a road lengthways but does not include a nature strip bicycle path footpath or shared path Downstream In the direction of the movement of traffic Dual Primary Signal Face The signal face mounted on a post either on the median at or near the right of the stop line or if there is no median or median is too narrow to the right and near the projection of the stop line Also see Primary Signal Face Du
193. etector The efficiency of the detection system is maximised by providing one loop per lane The dimensions and placement of loops affect performance and are discussed in the following sections Figure 8 2 Typical loop shapes a Rectangular I I l l l l l l l b Symmetripole d Slanted c Quadrupole ii e Double diamond 3 direction of travel AUSTROADS 63 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 8 3 4 Location of Detectors The location of the loop affects the functions that the detector is able to perform The types of vehicle loop detectors used for traffic signal control include i stop line detection ii advance detection and iii queue detection Based on a study of traffic signal control practice in Australia Akcelik 1995a as well as more recent experience a the setback distance for stop line detectors is generally 1 5 m but ranges from 0 3 m to 2 5 m b the detector loop length used for stop line detection is generally 4 0 m or 4 5 m however recent research indicates that shorter loop length could be appropriate especially for right turn lanes Ak elik Besley and Roper 1999 c in Queensland loop lengths in the range 1 2 to 3 0 m have been used and the current practice is 2 m loops at setback distances of 35 45 m for major roads and 6 m for minor roads 8 3 4 1 Stop Line Loop Detection
194. f each com ponent Australian Standards and other sources for technical specifications and reference to sections of this guide where the subject is discussed in detail Figure 4 2 shows various signal components 4 2 1 Signal Lanterns Signal lantern is an assembly comprising one or more signal aspects together with the means of connecting them to power supply and facilities for mounting the complete assembly AS 1742 2144 Signal aspect is a single optical system on a signal face capable of being illuminated at a given time See Section 5 Vehicular Lanterns These lanterns convey the control signals to vehicular traffic They include 200 mm diameter red yellow green and white aspects as well as 300 mm aspects see Section 5 2 3 Each aspect may have arrow masks or other qualifying symbols Pedestrian Lanterns These lanterns are provided for the control of pede strians Red and green symbol aspects are used Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Figure 4 1 The traffic signal system Traffic engineers Detector sensor units o amp o D 2 D e Loop feeds Loop sensor A Vehicle trajectories n A M Signal AAA displays d actuations System design Controller settings Instruction data Master control where area control applies Signal controller Movement demands Movement timing Circuit switching logic
195. face can provide more than one function as detailed in Table 7 1 A signal face does not adequately provide the function if two or more lanes of traffic separate approaching vehicles and the signal face 51 TRAFFIC SIGNALS Figure 7 3 Symbols used to describe signal faces 7 4 Signal Face Site refer to AS 1100 Part 401 and local Requ irements standards for additional symbols 7 4 4 Recommended Minimum Three aspect circular Number of Signal Faces Three aspect circular with i a The minimum number of signal faces for a given closed visor optional approach is three with the exception of special applications and facilities see Section 15 An approach with a primary a secondary and a tertiary signal face satisfactorily provides for all essential signal face functions while still providing a limited degree of safety in case of individual lamp failure 000 RAT Three aspect left arrow b TZ The minimum number of signal faces for each left turn movement is two They should be located in the primary and tertiary locations Where the E IT road left turning vehicles are turning into has a Three aspect right arrow median or island the tertiary signal face may be located on that median or island if a suitable post is provided split tertiary arrangement Signal faces for a channelised left turn carriageway are covered in Section 7 5 2 2 m Two aspect pedestrian c The minimum nu
196. fic lane Traffic island Traffic management Traffic sign Traffic signal Vehicle actuated Vehicle spacing Abstract The Austroads Guide to Traffic Engineering Practice provides a comprehensive coverage of traffic surveys analysis layout design traffic management and road safety standards and practices in Australia To date 15 parts of the guide have been published Part 7 Traffic Signals 2003 is a major revision of the 1993 publication It incorporates the latest practice in the safe and efficient design of traffic signal installations Part 7 presents detailed information and provides guidelines on collection of design data geometric elements signal system and components signal face layouts and display sequences signal phasing location of signal equipment traffic detection signal controllers pavement markings signs electrical design coordination of traffic signals installation checks and maintenance and special applications including advance warning signals emergency vehicle facilities public transport priority bicycle facilities roundabout metering signals ramp metering signals special intersection treatments overhead lane control signals single lane operation and portable signals left turn on red and metering signals at sign controlled intersections Appendices provide detailed discussions on human factors and vehicular traffic characteristics relevant to traffic signal control provides guidelines for determining
197. fic signal installations This edition is a major revision of the 1993 publication and incorporates the latest practice throughout Australia It has been pre pared after extensive consultation with Australian State Territory and New Zealand authorities It is hoped that it will give readers a better insight into the Australian and New Zealand practice and be helpful in developing improved control practices for the benefit of road users This document presents detailed information and pro vides guidelines on collection of design data geometric elements signal system and components signal face layouts and display sequences signal phasing location of signal equipment traffic detection signal controllers pavement markings signs electrical design coordi nation of traffic signals installation checks and main tenance and special applications including advance warning signals emergency vehicle facilities public transport priority bicycle facilities rrundabout metering signals ramp metering signals special intersection treatments overhead lane control signals single lane operation and portable signals left turn on red and metering signals at sign controlled intersections Appendices provide detailed discussions on human factors and vehicular traffic characteristics relevant to traffic signal control provide guidelines for determining signal timings and give a complete worked example A glossary of terms is included at the st
198. ficiencies in the geometric layout see the worked example in Appendix D Detailed geometric characteristics of the intersection as discussed in this section need to be considered when improving an existing intersection and designing of a new signalised intersection 3 2 Traffic Lanes 3 2 1 Lane Arrangements The number of lanes and thus the capacity of each approach is determined by the total available width and the scope for widening of the approach and the traffic volume on that approach To increase the capacity of an intersection it is necessary to provide additional capacity on the critical approach or approaches An approach is critical if its capacity is limiting the capacity of the intersection with a given flow pattern Different approaches can be critical with different flow patterns i e different times of day Increasing the capacity of any critical approach may also increase the capacity of other critical approaches as additional green time can be given to the other approaches Increasing the number of lanes in order to increase capacity can be achieved by either reducing the width of existing lanes or by widening the approach and departure carriageways to introduce short lanes on the approach and departure sides turn pockets and flares and providing appropriate tapers to allow proper usage of lanes Recommended lane widths are given in Austroads GTEP Part 5 The capacity gained from lanes with limited queue
199. green time for Phase C is selected as 6 s Figure D 5 Lane flow capacity and performance results for Design 1 Austroads Guide TEP Part 7 Traffic Signals Worked Example TEP7D1 Design 1 Two Phase Intersection ID TEP7A Actuated Coordinated Signals Cycle Time 102 Table S 7 Lane Performance Effective Red Arv Flow Cap Aver Eff Queue Shrt Lane amp Green Times sec veh veh Deg Delay Stop 95 Back Lane No R1 G1 R2 G2 h h Satn x sec Rate vehs m m South Main Road South 1 LT 54 48 0 0 524 857 0 612 20 2 0 62 18 4 136 2T 52 50 0 0 552 902 0 612 16 5 0 54 17 9 132 3R 86 16 0 0 65 86 0 759 59 9 0 80 4 3 30 East Side Street East 1 LT 62 40 0 0 153 301 0 507 27 5 0 66 6 2 46 50 2 TR 73 29 0 0 211 416 0 507 372 0 75 10 7 77 North Main Road North RE 54 48 0 0 691 861 0 802 13 5 0 62 23 1 172 2T 52 50 0 0 719 897 0 802 8 8 0 51 21 0 156 3R 75 27 0 0 230 142 1 624 630 0 2 32 49 2 330 West Side Street West 1 LT 68 34 0 0 151 275 0 547 32 8 0 70 6 8 50 50 2 TR 69 33 0 0 271 496 0 547 34 1 0 75 13 2 95 142 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 APPENDIX D WORKED EXAMPLE Figure D 6 Proposed intersection layout Design 2 2 o No Stopping Zone 50 Parking ELP Shopping 70 centre 12 8 Clearway 24 5 Street 12 8 32 lt Level 50 No Stopping Zone
200. h Wales Sydney Australia FISHER A J and COLE B L 1974 The photometric requirements of vehicular traffic signal lanterns Proc ARRB 7th Conf 7 5 pp 246 264 ARRB Transport Research Ltd Vermont South Australia FHWA 1996 Traffic Control Systems Handbook Federal Highway Administration Report No FHWA SA 95 032 Washington D C U S A FOX J C GOOD M C and JOUBERT P N 1979 Collisions with Utility Poles Summary Report Department of Transport Office of Road Safety Canberra GARDNER R 1996 Vehicle characteristics In Traffic Engineering and Management Eds K W Ogden and S Y Taylor Institute of Transport Studies Department of Civil Engineering Monash University Melbourne Australia Reprinted 1999 pp 3 20 GAZIS D HERMAN R and MARADUDIN A 1960 The problem of the amber signal light in traffic flow Operations Research 8 1 pp 112 132 154 GLAUZ W D and HARWOOD D W 1999 Vehicles In Traffic Engineering Handbook Ed J L Pline Prentice Hall Eaglewood Cliffs New Jersey U S A Fifth Edition pp 50 77 HEBB D O 1955 Drivers and the conceptual nervous system Psychological Review Vol 62 pp 243 254 HOMBURGER W S HALL J W REILLY W R and SULLIVAN E C 2001 Fundamentals of Traffic Engineering Course Notes UCB ITS CN 01 1 Institute of Transportation Studies University of California Berkeley U S A 15th Edition HULSCHER FR 1974 Practical
201. h movement would be stopped when the side road movement operates e g in Phase C in Figure 15 5 b Generally traffic signals should be installed on seagull intersections only where right turn vehicles from the stem of the T intersection do not have to merge with through traffic on the departure and weave across through traffic to turn left just beyond the signals Any merging by these right turn vehicles can result in rear end collisions If traffic has to merge on the departure the safest option is for through traffic in the left most lane to merge to its right This means providing right turn vehicles from the stem of the T junction with their own lane or lanes on the departure as shown in Figure 15 5 a A capacity and performance evaluation should be carried out to determine if the seagull operation is more efficient than other intersection design options This should account for lane underutilisation on the major approach road from the left of the T intersection that is likely to be caused by this treatment Figure 15 5 Seagull T intersection geometry and signal phasing a Intersection geometry b Signal phasing Phase A Phase B Phase C T gt lt _ ED 102 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 15 9 2 Paired Intersections Paired intersection is a term used for two closely spaced intersections with limited queuing space betw
202. he maximum available deceleration expressed in units of the gravitational acceleration rate For example the deceleration rate of a 3 0 m s2 used in Appendix C Section C 4 6 1 for determining yellow time implies a friction coefficient of f 0 31 on a level road G 0 In this case using Equation B 2 2 for an initial speed of v 60 km h a braking distance of D 46 m braking time t 5 6 s and a total stopping distance of D 71 m are found While Equations B 2 1 and B 2 2 are based on a constant acceleration model Akcelik and Biggs 1987 described a polynomial model that better represents the S shaped speed time profiles of vehicles in acceleration or deceleration However they found that percentage errors in deceleration distances predicted by the constant deceleration model compare reasonably well with prediction errors from the polynomial as well as linear and sinusoidal models Note that the friction coefficient varies due to many factors such as types and conditions of tyres and road surface Clean wet hard surface pavements and tyres in reasonable condition are assumed in determining the value of friction coefficient for traffic control and design purposes Gardner 1996 Austroads 2000 Guide to the Selection of Pavement Surfacings gives information on the skid resistance and surface texture levels at which investigation might be considered to determine whether remedial treatment is required A marked r
203. he mini mum phase green time due to a pedestrian movement equals or exceeds the duration of vehicular running intervals for the phase Methods to determine pedestrian Walk Time and Clearance Time settings are described in Section C 5 C 3 3 Actuated Controller Settings Selecting appropriate values of controller settings for efficient operation of actuated signals for a given phas ing system is not an easy task The location number and other characteristics of detectors affect the choice of actuated signal settings also For the purpose of determining the values of actuated controller settings it is necessary to identify the pro portion of flow in the critical lane Critical lane is the lane that places the highest demand on green time in a given phase or signal group considering all movements in the phase or group In terms of capacity analysis this is the lane with the largest degree of saturation demand flow rate to capacity ratio Where capacities of all lanes are equal and all lanes are utilised equally this is the lane with the highest demand flow rate A simple manual method to determine the proportion of flow in the critical lane is given in Ak elik 1995b Appendix B The methods recommended for determining actuated signal controller settings are described in Sections C 4 to C 6 Typical signal controller settings used in Australian practice are given in Table C 2 Ak elik 1995a b AUSTROADS APPENDIX C SIGNAL
204. he others In such systems usually one of the signal controllers assumes the role of master and may contain a number of timing plans to suit traffic conditions at different times An intersection signal controller with a nearby midblock signalised crossing controller can be coordinated via local interlinking In this case the intersection controller imposes restraint periods on the pedestrian signal con troller during which the introduction of the pedestrian phase is inhibited AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 A variety of local interlinking systems have been used in the past They have now been replaced by wide area control systems Section 73 4 3 13 4 2 Synchronous Linking The synchronous or cableless linking system can be applied to a large system of signals without relying on a central computer e g the SCATS Flexilink mode of operation as discussed in Section 13 5 3 Coordination of signals is achieved by reference to an accurate clock in each signal controller These clocks are initially set to exactly the same time and maintained in synchronism by reference to the mains supply frequency Each controller contains one or more signal timing plans and a weekly schedule for the introduction of the plans according to the time of day and day of the week The timing plans include the cycle time and green splits to be used and because the clocks are synchronised the cycle position of each controller can
205. he roundabout b TZ To stop traffic at a signalised crossing on a left turn slip lane where traffic may continue to filter after the pedestrian phase has finished comprising red and yellow circular or arrow aspects Figure 5 6b In this case green circle or green arrow is not used in order to avoid conflict with the requirement to give way to other traffic at the slip lane give way line c Yellow and green arrow aspects on the far right side of a divided road dual secondary signal as shown in Figure 7 1b in Section 7 to reassure right turn traffic in a wide intersection that they may proceed Figure 5 6c d Split tertiary signals comprising yellow and green arrows which are used where the road that left turners are turning into has a median or island Figure 5 6d Refer to Section 7 4 1 b Figure 5 6 Two aspect signal face layouts a Roundabout metering b Slip lane with or signalised crossing signalised crossing near a roundabout entry d Split tertiary signals for wide intersections c Dual secondary signals for wide intersections e AUSTROADS SIGNAL FACE LAYOUTS AND DISPLAY SEQUENCES 5 4 Face Layouts with Right Turn Arrow Aspects 5 4 1 Six Aspect Signal Face Layouts with Right Turn Arrow Aspects A six aspect signal face layout with red yellow and green arrow aspects can be used to independently control right tur
206. herefore exclusive right turn lanes should be provided where practical If the right turn volume is low a turn ban prohibition of the right turn movement may be considered Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS The use of a shared through and right turn lane adjacent to an exclusive right turn lane may be considered where right turn traffic demand volumes are large Impli cations of this in terms of signal phasing should be considered carefully see Section 6 There should be sufficient clearance distance between swept paths for opposing right turn movements that occur simultaneously Where there is insufficient width to allow opposing right turn movements to occur simultaneously these turns should be separated in the signal phasing Section 6 or banning one or more right turn move ments may be considered 3 2 3 Left Turn Lanes The use of exclusive left turn lanes should be considered where left turn traffic demand volumes are large Slip lanes may be provided for left turn movements These lanes may be controlled by signals or by give way rule The TURN LEFT AT ANY TIME WITH CARE Section 11 3 7 or GIVE WAY signs may be used at slip lanes not controlled by traffic signals A high entry angle exclusive slip lane subject to give way control is shown in Figure 3 1 East approach Safety of pedestrians crossing in front of slip lanes is an important issue that should be addressed carefully in the
207. hicle e g left turn lane through lane right turn lane bus lane Also see Shared Lane Extension Period The interval of variable length during the green period that begins after a demand for another phase is regis tered following the minimum green interval and ex tends according to vehicle detector actuations subject to a maximum green extension setting in the controller Face see Signal Face Filter Turn A turning movement that must give way to and find safe gaps in conflicting opposing vehicle or pedestrian traffic before proceeding e g filter right turn slip lane left turn left turn on red Also called Opposed Turn Finishing Offset Coordination Coordination of the end times of green periods using a signal offset that equals the average uninterrupted travel time in the travel direction so as to minimise delay along the route Also see Offset Fixed Time Control A signal control method that allows for only a fixed sequence and fixed duration of displays Fixed Time Plan Selection A signal coordination method that uses predetermined signal timing plans introduced according to a weekly schedule or timetable Flexilink The cableless linking mode of operation in the SCATS control system used to maintain a level of signal coordination in the event of failure of the regional computer or parts of the communication system Flow Rate Number of vehicles or pedestrians per unit time passing arriving or departing
208. i a Walk period indicated by a steady green person display that permits pedestrians to commence their crossing ii a Clearance period consisting of a red flashing standing person display that permits pedestrians to complete their crossing but prohibits pedestrians starting to cross and iii a Don t Walk period consisting of a steady red standing person display that prohibits crossing Pedestrian aspects are shown in Figure 5 1 in Section 5 In some jurisdictions the steady red Don t Walk display is extinguished after a short period until the pedestrian demand is registered see Section 5 8 2 The flashing rate for the Clearance period should be approximately 1 Hz with an on off ratio of 60 40 6 5 2 Pedestrian Movements at Intersections a Under normal conditions the introduction of a green pedestrian display would be subject to a pedestrian demand but where pedestrian move ments are consistent and heavy automatic intro duction of the relevant green pedestrian display may be considered Normally pedestrian movements Walk displays are introduced with the parallel vehicle movements If the number of pedestrian vehicle conflicts is high or the speed of approaching vehicles is high red arrow or flashing yellow arrow displays may be required to protect pedestrians If this creates phase transitions that are too complicated or additional phases are needed to fully service the vehicle movements an exclusive pedes
209. ia BLANKS H S DAVIES L W and HULSCHER F R 1976 Failsafe requirements of road traffic signal equipment Proc ARRB 8th Conf 8 5 pp 27 35 ARRB Transport Research Ltd Vermont South Australia Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS BLEVIN W R 1972 Colour Specification IES Convention CHARLES P 2001 Time for a change Traffic Technology International June July issue pp 68 71 COLE B L and BROWN B 1966 A preliminary examination of the optimal performance of road traffic signal lights Australian Road Research 2 8 pp 24 32 COLE B L and BROWN B 1968 Specification of road traffic light intensity Human Factors 10 3 pp 245 254 CUMMING R W 1964 The analysis of skills in driving Australian Road Research 1 9 pp 4 14 DAVIES L W HULSCHER F R and SYME J W 1978 Failsafe requirements of road traffic signal equipment Il Proc ARRB 9th Conf 9 5 pp 69 78 ARRB Transport Research Ltd Vermont South Australia DEAN K G MACDONALD D E and MORRIS D J 1981 Vehicle Detector Loop Configurations Phase 2 Report No R81 3 AWA Research Laboratory DIBLEY T and REID J 1990 Acceleration Deceleration Profiles at Urban Intersections Report for Transit New Zealand Australasian Traffic Survey Pty Ltd Melbourne FISHER A J 1971 A Photometric Specification for Vehicular Traffic Signal Lanterns Report 3 parts University of New Sout
210. ial and subsequent detections and as a consequence the design and oper ation of traffic responsive signal control are determined 8 1 2 Vehicle Detection Modes The sensor units for vehicle loop detectors have a switch to allow the detector to be operated in one of two modes a Presence mode In this mode the sensor unit produces a continuous output whenever a vehicle is in detection zone The duration of the output occupancy time depends on the length and speed of the vehicle Both moving and stationary vehicles can be detected in the presence mode b Passage mode In this mode the sensor unit produces a brief pulse when a vehicle enters the detection zone thus detecting only moving vehicles regardless of their length or speed Passage detection does not provide further pulses if stationary or very slow moving traffic occupies the detection zone Figure 8 1 shows basic traffic parameters relevant to measurements by a vehicle loop detector system in presence detection mode These include spacing distance headway time occupancy time space or gap time and distance vehicle length as well as the fundamental traffic parameters speed flow rate and density which are not shown in the figure The defi nition of spacing and headway parameters with refer ence to the front ends of the leading and following vehicles is adopted in Figure 8 1 Relationships among basic traffic parameters are summarised in Appendi
211. ian clearance time s L pedestrian clearance distance m and Voc pedestrian walking speed m s ii Determine the durations of the Clearance 1 and Clearance 2 intervals t and t from ty C 5 3 ta B toc ail where intergreen time s see Section C 4 6 and tj total clearance time s from Equation C 5 2 134 The pedestrian clearance distance in Equation C 5 2 is based on the length of the marked crossing between kerb lines Where the sides of the crossing are of unequal length the length of the longest side is used If a median exists its width is included in the clearance distance when crossing both carriageways in one move ment i e the pedestrian clearance distance includes both carriageway widths as well as the median width However if the Walk Time is calculated using Equation C 5 1 for the case when crossing a wide road with median in one movement the clearance distance in Equation C 5 2 should be based on the larger of the two carriageway widths i e excluding the median width Where a median is wide enough to store pedestrians a staged signalised crossing can be used see Section 6 5 In this case the crossings are treated separately and the width of appropriate carriageway is used as the clearance distance for each crossing Where an exclusive pedestrian phase is provided at an intersection the shortest distance between diagonally opposite corner kerb radii for the longes
212. ic experiences an unexpected conflict with a signalised pedestrian movement This can occur where the signalised crossing is located a short distance down the street being 76 Figure 11 2 GIVE WAY TO PEDESTRIANS R2 10 sign GIVE WAY TO PEDESTRIANS 11 3 4 Pedestrian Scramble Crossing Sign The PEDESTRIANS MAY CROSS DIAGONALLY or pedestrian scramble crossing sign allows pedestrians to cross the road diagonally at signalised intersections where an exclusive pedestrian phase is used sign R3 5 shown in Figure 17 3 During the scramble crossing phase all pedestrian movements including diagonal movements operate simultaneously within the marked limits of crossing see Section 10 3 2 Scramble crossing phases must operate full time They should be installed only where there is demonstrated need for pedestrians to cross diagonally and there are delay reductions to vehicles and pedestrians AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 SIGNS Figure 11 3 Pedestrian scramble crossing R3 5 signs 11 3 5 Signs to Control Turning Movements Signs to control turning movements consist of Turn Ban signs and Must Turn signs Figure 11 4 These signs must always be consistent with signal arrow displays and or pavement arrow markings Generally these signs are erected on the same traffic signal posts as the signal faces which control the movement 11 3 5 1 Turn Ban Signs NO LE
213. ic management and environmental objectives such as improving the level of service of major arterial roads to reduce the pressure on residential streets and central business district CBD areas and reducing fuel consumption and pollutant emissions In addition to improving the level of service of preferred routes coordination may be utilised to discourage the use of certain routes by providing bad progression also reducing green times at intersections along the route to make those routes unattractive The benefits of traffic signal coordination were reported in Australian studies by Bastable 1980 Luk Sims and Lowrie 1983 and Negus and Moore 1984 Further references and a summary of benefits of signal coordin ation can be found in Lowrie 1996 These benefits include a reduction in travel time and delay b c TZ reduction in the number of stops improved capacity of closely spaced signalised intersections d reduction in intersection accidents e reduction of noise levels air pollution and energy fuel consumption f achievement of other area or corridor traffic management goals VS benefits from the increased capacity of the road network which helps to avoid expensive road widening projects g 13 2 Principles of Coordination 13 2 1 Fundamentals of Signal Coordination There are three fundamental control parameters in preparing a signal coordination plan
214. iently a lagging right turn sequence may be an option see Section 6 3 3 If neither right turn can be banned a leading right turn sequence may be an option if one of the right turns can filter safely and efficiently and the other cannot filter efficiently see Section 6 3 2 If both right turns cannot filter efficiently then a diamond overlap sequence may be an option see Section 6 3 5 If both right turns are required but the diamond turn is not practical a split approach sequence may be an option see Section 6 3 4 41 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 6 3 2 Leading Right Turn Phasing A leading right turn sequence is where a right turn phase precedes the phase in which the opposing through movement runs see Figures 6 7 and 6 4 In Figure 6 4 the leading right turn movement from the West approach runs in Phase A and the opposing through movement from the East approach runs in Phase B A leading right turn phase is controlled by three aspect right turn arrows red yellow green in a six aspect signal face or by two aspect right turn arrows yellow green in a five aspect signal face see Figures 5 4 and 5 7 in Section 5 This phasing is a suitable option where an arrow controlled right turn has a filter right turn from the opposing direction the right turn movement from the East approach in Figure 6 4 which cannot be banned and is able to filter safely and efficiently Wh
215. in Hulscher and Sims 1974 Figure 8 3 illustrates the recommended loop layout and configuration for stop line detectors The derivation of the loop configuration symmetripole is given in Dean et al 1981 The transverse spacing between the outer loop conductors and the lane boundary must be chosen to minimise a unwanted detection of vehicles in the adjacent lane overcounting and b the number of undetected vehicles especially two wheeled traffic which do not travel through the loop s detection zone undercounting The optimum transverse spacing is achieved when overcounting errors are equal to undercounting errors Similarly the gap between the two sections comprising each 4 5 m loop must be kept to a minimum to give good longitudinal response for all classes of vehicle However the smaller this gap is made the more overall sensitivity is reduced A spacing of 0 5 m as shown in Figure 8 3a is a good compromise figure 66 8 4 Pedestrian Traffic Demands 8 4 1 Pedestrian Detection Push button detectors are the most common detectors for pedestrians To register a demand a pedestrian must actuate the appropriate pedestrian push button When the button has been pressed an illuminated panel pedestrian indicator when present may be used to indicate to the pedestrian that the demand has been recorded by the controller The illuminated panel switches off when the demand is satisfied Audio tactile push buttons
216. ing measure ment corresponds to a unique speed value On the other hand Figure B 3 shows that under all except saturation flow conditions v 42 km h h 1 75 s APPENDIX B VEHICULAR TRAFFIC FACTORS each headway measurement corresponds to two speed values These represent two contrasting traffic flow conditions i e free flowing conditions with high speeds vs forced flow congested conditions with low speeds For example a 3 0 s headway represents both 1200 veh h at 67 km h and 1200 veh h at 11 km h This severely restricts the application of passage detectors for traffic control In contrast with the headway measurement each occupancy time or space time measurement by presence detection may correspond to a unique speed value as seen in Figure B 4 However it is seen that occupancy times increase sharply and the space time becomes zero when speed drops to very low values Zero space time continuous occupancy is a result of the bridging effect that occurs at low speeds when the front end of the following vehicle enters the detection zone before the rear end of the leading vehicle exits Table B 1 Basic traffic parameters observed at eighteen signalised intersections in Sydney and Melbourne Through Right Turn Traffic Lanes Traffic Lanes Saturation or maximum flow rate s or q veh h 2057 2033 Free flow speed v km h 69 65 Jam spacing Lni m 7 0 6 4 Jam gap length Lj m 2 6 2 0 Jam density kj veh km
217. ion anticipated in the design Section 8 i are unusual vehicles being missed by detectors and are they in sufficient numbers to justify special detection techniques 14 3 Maintenance Traffic signal installations require maintenance to ensure satisfactory operation in terms of capacity and safety Regular checks should be made to ascertain whether signal settings are still appropriate for the prevailing traffic conditions Appendix C This aspect is some times overlooked during routine maintenance and only examined when a major problem becomes evident 14 3 1 Maintenance Management Signal maintenance management aims to minimise costs while maximising the availability and life of the installation AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 The level of maintenance required should be considered during design For example lamp burn outs can reduce the number of displays below the minimum considered necessary for safe control If at the design stage some additional displays were provided the time taken to respond to advice of a lamp burn out would be less critical 14 3 2 Maintenance Records To adequately schedule maintenance it is necessary to estimate the Mean Time Between Failure MTBF and Mean Time To Repair MTTR for various signal com ponents If this information is sufficiently detailed it may also be useful in identifying those components that may reduce the reliability of the signal system Main
218. ion in each Australian State or Territory and in New Zealand Before con struction of any signal installation compliance with the relevant statutes and regulations must be assured 1 4 Associated Standards and Manuals This guide is complementary to AS 1742 Manual of Uniform Traffic Control Devices and other associated Australian Standards dealing with components of signal systems see Table 4 1 in Section 4 The guide should be used in conjunction with those standards Standards Australia 1975 2000 Austroads has issued a number of publications relevant to signalised intersections In particular various parts of the Guide to Traffic Engineering Practice GTEP Austroads 1988 1999 are companions to this guide Examples of local guidelines are a Traffic Signal Practice Design Roads and Traffic Authority of New South Wales RTA NSW 1992 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS b Traffic Engineering Manual Volume 1 Traffic Management VicRoads VicRoads 1997a c Road Planning and Design Manual Queensland Department of Main Roads QMR 2000 d Manual of Traffic Signs and Markings Parts and II Transit New Zealand and Land Transport Safety Authority 1997 1998 1 5 Guidelines The following general guidelines can be used to determine whether installation of traffic signals is justified at an intersection subject to following considerations a Where alternative or additional
219. ipline or manoeuvring where required and f minimising competing information in the immediate vicinity of traffic signals Figure A 3 Postulated relationship between performance and arousal after Hebb 1955 o o E oO E 5 Optimal level SE Ha Increasing emotional Increasing disturbance alertness positive emotion anxiety point of waking deep sleep Arousal AUSTROADS APPENDIX A HUMAN FACTORS For safety reasons pedestrian movements must be care fully analysed when designing traffic signals Pedestrians will ignore the protection offered by pedestrian signals if they are faced with what they consider is an unrea sonable delay or a badly located signalised crossing Determination of pedestrian Walk and Clearance times for pedestrian signals is discussed in Appendix C A 3 Vision The detection of a signal is dependent on intensity colour luminous contrast with the background position of the signal in the visual field of the observer and its exposure time Three visual attributes are of major importance in the context of drivers ability to perceive and respond to traffic signals These are a visual sensitivity b visual acuity and c colour perception The same attributes apply to pedestrians who are also required to obey traffic signals but pedestrian response characteristics are not as critical because of their slower movements Some pedestri
220. ised They should not be used to indicate a turn where the turn is restricted during certain hours of the day 10 6 Raised Pavement Markers These devices may be used to augment painted lines at traffic signals where it is considered necessary to improve night or wet weather visibility or to indicate paths that would otherwise be confusing Reflective markers are often used on intersection approaches whereas non reflective markers may be used to delineate lanes which change direction through the intersection e g curves and misalignment between approach and departure lanes AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 11 Signs 11 1 Introduction This section refers to traffic signs that are associated with traffic signal installations Unless otherwise specified in this section all signs should be designed and located in accordance with AS 1742 Refer to AS 1742 Part 1 for a general index of signs and Section 2 of AS 1742 Part 2 for treatment at intersections Sign numbers given in this section refer to those based on these standards In New Zealand reference should be made to the Manual of Traffic Signs and Markings Part Transit New Zealand and Land Transport Safety Authority 1998 11 2 General Requirements 11 2 1 Erection At signalised intersections signs must not be located where they obscure signal displays or limit the sight distance to conflicting or merging traffic Sight distance is important in
221. istance m t reaction time s v initial speed before braking km h f longitudinal coefficient of friction assumed constant throughout braking and G approach grade per cent grade divided by 100 negative value for downhill grade and positive value for uphill grade e g 0 05 for 5 per cent downhill grade While a general purpose reaction time of t 2 5 s is recommended in the literature possibly appropriate for unalert drivers in general driving conditions Gardner 1996 Lay 1985 a reaction time of t 1 0 or 1 5 sis used in Appendix C Section C 4 6 1 for determining the yellow time at signals Using t 1 5 s the vehicle stopping distance can be determined from 2 _ a Ni Te B 2 2 The above expressions assume a constant deceleration rate ay in m s from an initial speed v km h to zero final speed and calculate the braking distance from D 0 5 v 12 96 ay where a g f G for braking on a road with frictional coefficient f and grade G g is the gravitational acceleration rate g 9 8 m s The braking time t in seconds for constant acceleration rate can be determined from tj 7 2 D vj v 3 6 ag where v is in km h and ay is in m s Accessed by AR M VICROADS on 02 Jun 2005 The road grade G is seen to add to or subtract from the value of the friction coefficient f For braking on a level road G 0 a g f Thus the friction coefficient represents t
222. it is the duration of the period when the detection zone is occupied by a vehicle Space time is the time between the detection of two consecutive vehicles when the presence detection zone is not occupied It is equivalent to gap time less the time taken to travel the effective detection zone length Speed is the distance travelled per unit time In a time distance diagram the slope of the trace of a vehicle is its speed as seen in Figure B 1 The relationships among the basic parameters described above and shown in Figure B 1 are summarised below time based parameters are in seconds distance based parameters are in metres and speed is in m s L L L hv 3 6 B 3 1 L L l t v 3 6 B 3 2 h 36L v t t t t 8 33 t 3 6L v B 3 4 t 3 6 Lp L v t 3 6L v B35 t h t 3 6L v B 3 6 t h t 23 6 L L v B 3 7 v 3 6L h 36L t B 3 8 where L spacing m L space gap length m L vehicle length m Lb effective detection zone length m h headway seconds t vehicle passage time seconds ts gap time seconds t occupancy time seconds t space time seconds and v vehicle speed km h AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 APPENDIX B VEHICULAR TRAFFIC FACTORS Figure B 1 Diagram showing the relationships among basic traffic parameters Distance A A ls i 1v ts Ls Lp v Ly Lh Ls ls E
223. ith positioning and determining the radii of turn lines Austroads 1995 It is suggested that a gap of 1 2 to 2 0 m is provided between the overhang lines of the Austroads templates At major urban intersections with double right turn lanes from opposite directions it is necessary to select the design vehicles for the turns e g car and semi trailer from both directions Turn lines should not be carried through pedestrian crosswalks 10 3 Transverse Lines 10 3 1 Stop Lines Stop lines indicate to drivers the point behind which vehicles must stop when required e g during the red interval Where approach speeds are 80 km h or above lines 600 mm wide are preferred elsewhere lines 300 mm wide may be used To minimise the controlled area stop lines should generally be located as follows a Intersections with signalised crossings 1 2 m to 2 0 m desirable 0 6 m minimum in advance of and parallel with the crossing This distance is increased where bicycle head start storage areas are provided see GTEP Part 14 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS b TZ Urban intersections without signalised crossings generally at or just in advance of the primary signal post and not less than 1 m from the kerbline projection in the intersecting street except as provided for in c Additional clearance from the kerbline may be required for occasional pedestrian movement Rural Intersections or intersecti
224. ix C to determine initial controller settings D 5 3 1 Controller Operation Sheets Controller Operation Sheets are used to record operat ional specifications and all related information including controller type signal group allocation detector map layout and numbering detector functions phasing diagram approach timing details controller time settings including pedestrian time settings signal coordination details and special functions Utilising the Controller Operation Sheets a personality to adapt a controller to the intersection is prepared by use of a generation program specific to the brand and model of controller being used These programs require considerable experience and expertise to implement effec tively The manufacturer or a professional with expertise in the particular controller being used should be consulted Figure D 15 Location of detectors for Design 2 ll C A1 detector B1 detectors C A2 detectors B2 detectors AUSTROADS 149 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS D 5 3 2 Detectors and Approach Timers b The approach timers are allocated as follows Detectors and approach timers must be decided before Phase A approach timer 1 A detectors the controller settings are determined These are Phase A approach time
225. l i Two aspect green yellow right turn arrows on a five aspect signal face The green arrow indicates that the vehicle can turn unopposed A green circle without the green arrow permits the vehicle to filter 39 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Figure 6 2 Two phase system with filter right turns and parallel pedestrian movements Phase A Phase B LS t e Figure 6 3 Conflict points in the two phase system shown in Figure 6 2 Figure 6 4 Three phase system consisting of leading right turn phasing on the East West road and a through phase with filter right turns on the North South road Phase A Phase B Phase C lt gt lt lt m FPT I e i N YA S Ec We 40 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 SIGNAL PHASING Figure 6 5 Three phase system consisting of lagging right turn phasing on the East West road and a through phase with filter right turns on the North South road Phase A Phase B Phase C A gt A gt Aum Deed Done ue o a gt gt Q v CY NRT v ii Red Arrow Drop Out Three aspect red yellow green right turn arrows on a six aspect signal face are provided but the red arrow extinguishes drops out and the adjacent green circle display permits filter turns after a few seconds in the through phase iii Flashing Yellow Arrow As an alternative to blanking the
226. l controllers can also be used to control overhead lane signals ramp metering signals metered roundabouts and similar devices Where two devices are very closely spaced there can be advantages in using one controller for both devices provided the controller has sufficient signal groups AUSTROADS SIGNAL CONTROLLERS This reduces installation and recurrent costs and guar antees traffic progression offsets between the two devices but increases the complexity of the personality The personality specifies which signal groups run in each phase the sequence of phases detector functions detector alarm conditions and default time settings Signal groups can be controlled conditionally within a phase e g in a diamond overlap phase see Section 6 3 or completely independently of the phasing e g slip lane vehicle and pedestrian groups Where there are unusual operations such as a railway interlink the personality logic can be quite complicated 9 5 Preventing Hazardous Displays Hazardous displays arise from failures in the mech anisms that switch power to the signal lanterns These hazards can be minimised by interlocked switching and or conflict monitoring The general principle is that if a signal group is showing green when it should not then conflicting signal groups are forced to red Interlocked switching is used with relay switching of lamp circuits Switching a green to one signal group will open the circui
227. l faces add to the visual clutter at the intersection and add to intersection operating costs The provision of additional signal faces that are not warranted may become confusing 52 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 7 4 2 Dual Primary Signal Faces A dual primary signal face is normally provided when there is a median island of sufficient width and a there are two or more approach lanes and or b there are right turn arrow aspects 7 4 3 Overhead Signal Faces 7 4 3 1 Overhead Signal Warrants a Overhead signal faces are expensive to install and to maintain Their use should be minimised They are required in the following situations i where the stopping sight distance to the post mounted signal face is inadequate e g because of vertical or horizontal alignment awnings poles trees or similar sight obstructions and ii where the roadway is too wide for kerb mounted signal faces to fall within the driver s line of sight b TZ Overhead signals may be omitted if it is likely that they could appear to apply to an adjacent upstream signalised intersection 7 4 3 2 Overhead Signal Location a The primary signal face location is preferred for overhead signal faces see Table 7 7 because it provides i The greatest sight distance from the stop line and ii Warning and stopping functions when dual primary signal faces are warranted but cannot be provided b TZ Pr
228. l the maximum extension green time after minimum green intervals available to each phase or signal group Set the maximum allowable time period between successive detector actuations before the movement terminates gaps out Allow the termination of some signal groups earlier than others To provide sufficient warning of the termination of the phase Provide a safe clearance for vehicles that cross the stop line towards the end of the yellow interval Set the period for which a detector must be occupied before a demand is recorded Set the desirable space time between successive detector actuations for efficient traffic flow Set the value of the sum of the excess of the actual space time over the space time setting at which the phase is terminated To allow appropriate red arrow display time considering driver reaction perception characteristics Set the duration of the green Walk display Set the duration of the Flashing Don t Walk display Provide a delay between the push button actuation and the placement of the pedestrian demand 100 120 seconds simple two phase 150 180 seconds complex phasing 0 6 seconds 4 10 seconds 0 5 2 0 seconds Depends on the distance of advance detectors from stop line see Section C 4 2 2 Choose for optimum traffic performance under different traffic conditions avoid unduly long cycle times see Table C 2 1 0 4 0 seconds O 10 seconds
229. leg is a one way approach and the right turn move ment from the West leg to the South leg is banned Pavement markings should reflect the physical direction of travel as appropriate as shown in Figure 15 7 This consideration also applies to three way and four way intersections where legs intersect at other than 90 degree angles e g Y junctions Signalised crossings may require special attention depending on the vehicle movements permitted in the same phase to ensure that there are no safety problems The inclusion of signal controlled bus bicycle or tram lanes can further complicate the signal phasing for this type of intersection Where possible these special vehicles should be controlled by normal vehi cular displays For intersections where legs intersect at other than 90 degree angles care needs to be taken to avoid the potential see through problem by ensuring that the green signals on one leg are not seen by drivers on an adjacent leg Figure 15 7 Example of an intersection with more than four legs a Intersection geometry b Signal phasing Phase A Phase B S A Phase D 104 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 15 10 Overhead Lane Control Signals Overhead lane control signals may be used to control a reversible flow lane as part of a peak period tidal flow scheme or to control lane usage at a toll station or a similar facility Overhead lane control signa
230. lock Signalised Crossing Warrants The need for a midblock signalised crossing depends on the probability of pedestrians being able to find suitable gaps in vehicular traffic stream This probability is decreased with the increased speed and increased volume and density of vehicles Other factors to consider include platooning of vehicle flows from upstream signals number of traffic lanes to cross pedestrian desire lines impact of future development as well as proportion of children elderly or handicapped pedestrians Justification for the provision of a midblock signalised crossing should be based on the potential pedestrian flows rather than the existing flows considering that this facility may attract additional pedestrians to the site AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 Provision of a midblock signalised crossing should be avoided within 130 m of a signalised intersection The following guidelines for midblock signalised crossings differ from those given in Austroads GTEP Part 13 Pedestrians and AS 1742 Part 10 As a guide a mid block signalised crossing may be considered if one of the following warrants is met a For each of four one hour periods of an average day the pedestrian flow crossing the road exceeds 250 ped h and the vehicular flow exceeds 600 veh h in both directions or where there is a central pedestrian refuge at least 1 2 m wide the major road flow exceeds 1000 veh h in both dir
231. ls Signs amp markings Visual characteristics Pedestrian Human characteristics behavioural characteristics Driver characteristics Vehicles characteristics Environment Road conditions Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS A 2 Human Behaviour The complexity of human behaviour makes it impossible to deal adequately with this vital subject apart from describing a few basic concepts within the scope of this guide Important aspects of human performance relevant to traffic control are information processing and decision making visual characteristics and information needs Ogden 1996 Various aspects of information pro cessing and decision making are discussed in this section and visual characteristics are discussed in Section A 3 Refer to Ogden 1996 for a discussion of key needs of road users in relation to traffic control namely conspicuity legibility comprehensibility and credibility Considerable evidence shows that humans can deal with only a limited amount of information at a time and that they require a measurable length of time to respond to events in their environment The length of time required to respond to an event depends amongst other things on the number of other activities or events being attended to the probability of the event occurring how far ahead the event can be predicted whether a subsequent important event is anticipated
232. ls are single aspect white arrow or red cross as shown in Figure 15 8 The white downward pointing arrow permits travel in that lane the red cross prohibits travel in that lane White arrows are used to ensure that no confusion exists with traffic signal control displays Where a lane control signal aspect display is not required to change since the traffic is always allowed to use the lane in the same direction it may be replaced by a fixed sign subject to various conditions including a The lane arrow shall be a downward pointing white arrow on a black background or black arrow on a white background b The lane cross shall be red on a white background TZ c The minimum signboard size shall be 600 x 600 mm d TZ On each set of signals across a roadway signals over lanes immediately to the left or right of reversible lanes shall be signal aspects and not sign alternatives e Sign alternatives shall be as conspicuous as the signal displays White portion of the sign shall comprise retroreflective material and external illumination shall be considered for this purpose Figure 15 8 Signal face layouts with white arrow and red cross aspects for overhead lane control AUSTROADS SPECIAL APPLICATIONS AND FACILITIES 15 11 Single Lane Operation and Portable Signals 15 11 1 Single Lane Operation Single lane roadway operation by means of traffic signals
233. lumns containing only a yellow aspect are not permitted d columns containing only red and green aspects are not permitted AND except in the case of a four aspect single column display as detailed in Section 5 3 3 e aspects of the same colour are located on the same horizontal level 22 Figure 5 4 Six aspect multi column signal co 0609 oe 0O Ge 069 5 3 3 Four Aspect Single Column Signal Face Layouts A single column of four aspects can be used consisting of red and yellow circular aspects and two green aspects circular and arrow or two arrows as shown in Figure 5 5 This is not permitted for overhead mounted signals Four aspect columns should not be used in multi column displays Figure 5 5 Four aspect single column signal face layouts 6 0 o oe 6000 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 5 3 4 Two Aspect Signal Face Layouts Where regulations permit two aspect signal face layouts Figure 5 6 are used in the following circum stances also see ramp metering signals in Section 15 8 and metering signals at sign controlled intersections in Section 15 13 a Roundabout metering signals see Section 15 7 or at signalised crossings near a roundabout entry comprising red and yellow circular aspects Figure 5 6a In this case a green circle is not used in order to avoid conflict with the requirement to give way at t
234. mal give way conditions just downstream of these signals see Sections 3 2 3 and 5 3 4 Figure 7 6 in Section 7 shows a signalised crossing on a two lane slip lane Staged Crossing Staged signalised crossings can be considered where median widths provide adequate storage for the pedestrian traffic and large Walk plus Clearance time values cause the intersection performance to deteriorate seriously The staged crossings should be offset to make it clear to the pedestrians that the crossings are separately controlled and to reduce the chance of pedestrians on one side of the road reacting to a Walk display on the far side of the road 47 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 6 5 3 Midblock Signalised Crossings At a midblock signalised crossing all vehicles must face a red display during the pedestrian Walk and Clearance periods i e while the pedestrian signals display green and flashing red signal An exception to this is the Pelican crossing which permits vehicles to proceed giving way to pedestrians by displaying a flashing yellow signal to the vehicles during the pedestrian Clearance 2 interval see Sections 1 5 2 5 7 1 and C 3 2 This helps to reduce delay to vehicle traffic 48 In the case of controlling pedestrians crossing two carriageways separately staged crossing median widths should provide adequate storage for pedestrians and the crossings should be offset for the same reaso
235. mary Signal Face The primary signal face for any approach is that signal face mounted on a post at or near the left of the stop line on that approach Secondary Signal Face The secondary signal face for any approach is that signal face mounted on a post on the downstream side to the right of that approach Tertiary Signal Face The tertiary signal face for any approach is that signal face mounted on a post on the downstream side to the left of that approach Dual Primary Signal Face The dual primary signal face for any approach is that signal face mounted on a post either a if there is no median or median is too narrow to the right and near the projection of the stop line as shown in Figure 7 1 a or b on the median at or near the right of the stop line on that approach as shown in Figure 7 1 b Dual Secondary Signal Face The dual secondary signal face for any approach is that signal face mounted on a post on the downstream side to the right of that approach in addition to the secon dary signal face located on the median Figure 7 1 b Overhead Signal Face Signal faces mounted on a mast arm see AS 2979 above the roadway are similarly designated as Over head Primary Overhead Secondary and Overhead Tertiary Signal faces Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Figure 7 1 Signal face designations for four way intersections a Undivided road approach at a cross road inte
236. mber of signal faces for each right turn movement is two They should be located as follows i ona divided road with medians of sufficient width in the dual primary and secondary qe Pedestrian push button locations ii otherwise preferably in the overhead primary OG S 002 eec Accessed by AR M VICROADS on 02 Jun 2005 and secondary locations or iii as a last choice in the primary and Table 7 1 Signal face functions secondary locations Location of Mein Funeions Periormed Furthermore if both the secondary and overhead ARR Waning ee ORRIN ae eae uvTn secondary are provided right turn aspects should Primary Yes Yes No No be placed on both Secondary Yes Yes On a divided road where there are two or more lanes turning right consideration should be given Tertiary t Yes Yes to installing a right turn signal face in the dual Dual Primary Yes Yes No No far right secondary location Overhead Primary Yes Yes No No d Atintersections where geometry physical features approach widths or other factors restrict the Overhead Secondary t Yes 5 functions provided by only three signal faces Overhead Tertiary Yes additional signal faces may be necessary for example at multiple leg intersections or where the These functions may also be provided depending on site controlled area is exceptionally large or complex geometry topography and other conditions Excessive numbers of signa
237. ments involved in the traffic control process is given in Figure A 1 The interfaces between the human elements and the external world are the senses and the most signifi cant sense is vision which is of particular interest Information transfer from the traffic control system to the road user is aided if the traffic signals signs and pavement markings match the human visual character istics of the majority of the population This involves visual acuity sensitivity to light and colour discrimi nation as well as the time related effects of perception and reaction On the other hand successful application of traffic signal control depends on the extent to which it matches the traffic requirements At low levels of traffic conflict between different road users moving at speed increases accident risk whereas under congested con ditions such conflict generates delays and builds up frustration Delay and the number of stops experienced by vehicles and pedestrians may not always be reduced by installation of traffic signals but the efficient use of signals may generally cause delays and the number of stops to be redistributed Similarly the number of acci dents may not decrease significantly after installation of signals but the type of accidents will be different and in general accident severity will be reduced Figure A 1 Basic elements interacting in the traffic situation Control system Detection Signa
238. metering may also be applied to similar situations on ramps leading onto roads other than freeways Metering signals may be used on a part time basis Two aspect red and green signals are used for ramp metering The sequence of aspect display is Green to Red to Green When metering is not required neither aspect shall be displayed A typical ramp metering signal layout for a one lane entry ramp is illustrated in Figure 15 4 The signals are driven by a ramp metering controller that permits one vehicle to enter the freeway each time the green signal is displayed In the case of ramps where traffic queues in two lanes at the metering signal a dual release system displays green signals to each queue alternately A minimum of two signal faces one primary and one tertiary shall be provided The distance from the associated stop line to the entrance ramp nose shall be sufficient to allow a vehicle stopped at the signals SPECIAL APPLICATIONS AND FACILITIES to accelerate to freeway speed before merging with the freeway stream Adequate provision for queuing at the signals should also be made including provision for possible queuing back beyond the ramp If a sign is used to indicate that the entry to the ramp is restricted it may take one of the following forms a A variable message sign with legend FREEWAY ENTRY RESTRICTED b A fixed FREEWAY ENTRY RESTRICTED sign with times of operation below the legend c A fixed FREEWA
239. model indicates an average deceleration rate of 1 3 m s and a corresponding maximum deceleration rate of 2 2 m s for stopping from an initial speed of 60 km h Based on these values average deceleration rates are seen to be approximately 60 per cent of the maximum deceleration rates B 2 2 Acceleration Characteristics Acceleration rates observed under normal operating conditions are also smaller than maximum acceleration rates that represent acceleration capabilities of vehicles the latter is relevant to for example design of acceleration lanes at interchanges Jarvis 1982 observed maximum acceleration rates in the range 1 1 to 3 9 m s and the corresponding average acceleration rates were in the range 0 8 to 1 2 m s Glauz and Harwood 1999 give maximum acceleration rates in the range 1 7 to 2 8 m s for cars and 0 2 to 0 9 m s2 for trucks and states that normal acceleration rates are less than 65 per cent of the maximum acceleration rates for cars Ak elik and Biggs 1987 reported that the observed values of the ratio of average acceleration to maximum acceleration in each acceleration manoeuvre were in the range 0 24 to 0 67 Akcelik Biggs and Lay 1983 The acceleration model for normal operating conditions for light vehicles at intersections given in Akcelik amp Associates 2001a indicates an average acceleration rate of 1 5 m s and a corresponding maximum acceleration rate of 2 7 m s for acceleration from stopp
240. movement from the West approach in Phase A in Figure 6 5 If filtering causes safety problems this right turn must be stopped using a red arrow display when the opposing through movement is operating full control 6 3 4 Split Approach Phasing Split approach phasing allocates separate phases to opposing approaches at four way intersections see Figure 6 1 The through and turning movements from each approach operate simultaneously and right turn movements are unopposed under this phasing Split approach phasing is controlled by four aspect signal faces i e three circular aspects red yellow green and a green arrow aspect see Figure 5 9 in Section 5 AUSTROADS SIGNAL PHASING Split approach phasing may also be appropriate where a side streets at an intersection are slightly offset so right turns cannot make a diamond turn or sight distance makes opposing filter right turn movements unsafe b TZ turn proportions vary significantly during the day requiring flexible shared lane arrangements or c a particularly heavy right turn movement is opposed by a very light movement in which case the right turn vehicles may fail to give way to opposing through vehicles Other phasing options should be evaluated against split approach phasing before adopting it since it may result in inefficient site operation However safety is a prime consideration in the evaluation 6 3 5 Diamond Overlap Phasing
241. n 2005 CONTENTS Tis SIENS nne aat det a bse eed RR Re Rehd ied b 80 De A E du un ca do 11 1 Introduction 2 2e i eh ER eR RR eb RU b Se oobi dew tween 11 2 General Requirements ccce De e DR rene dents 11 2 1 Bur C 11 22 jP riodic SIBHis sedges eie edP Rep e eR See Bed ac Cc C i en ba 11 23 Illuminated Signs 11 3 Signs at Signal Installations 11 3 4 Parking Signs 11 3 2 STOP HERE ON RED SIGNAL ARROW Signs 11 3 3 GIVE WAY TO PEDESTRIANS Sign 11 3 4 Pedestrian Scramble Crossing Sign 11 3 5 Signs to Control Turning Movements 11 3 6 U TURN PERMITTED Sign 11 3 7 TURN LEFT AT ANY TIME WITH CARE Sign 11 3 8 LEFT TURN ON RED PERMITTED AFTER STOPPING Sign 11 3 9 Hook Turn Only Sign 11 3 10 Traffic Signal STOP Sign 11 3 11 Warning Signs 4 4444 444444 ii eh d ee dde ee de he des 11 3 12 NOT IN USE SIEM 254 rasta des E eR E c Ga REQUE Ace 11 3 13 Fault Reporting Sign 11 3 14 Oth rSIgHS uns mim Algal ack iia eR DL Aca a does da RE Aad de 12 Electrical D sign
242. n Victoria e Department of Main Roads Queensland Main Roads Western Australia Transport South Australia e Department of Infrastructure Energy and Resources Tasmania e Department of Infrastructure Planning and Environment Northern Territory e Department of Urban Services Australian Capital Territory Commonwealth Department of Transport and Regional Services e Australian Local Government Association Transit New Zealand The success of Austroads is derived from the synergies of interest and participation of member organisations and others in the road industry ge Australia STANDARDS Handbook Endorsement NEW ZEALAND In December 1993 Austroads and Standards Australia signed a Memorandum of Understanding regarding the development of Standards and related documents primarily for the development and management of the Australian road system Standards Australia s support for this handbook reflects the cooperative arrangement between the two organisations to ensure there is a coordinated approach in this area In August 1995 Austroads Transit New Zealand and Standards New Zealand signed an agreement regarding the development of Standards and related documents for endorsement of the appropriate Austroads publications as SNZ handbooks Standards New Zealand and Transit New Zealand s support for this handbook reflects the cooperative arrangement with Austroads to ensure that there is a coordinated approach in this area Handbook No HB 19
243. n during the intergreen period between Phases A and B In some jurisdictions a flashing yellow arrow is used to protect pedestrian movements see Section 6 5 2 In Figure 6 7 this applies to left turn from the East approach in Phase A and to left turn from the South approach in Phase B Some jurisdictions allow left turn on red as a delay reduction measure subject to various criteria being met see Section 15 12 This arrangement permits vehicles to turn left through a red circle display after first stopping at the stop line provided it is safe to do so When unsignalised slip lanes are provided for left turn movements vehicles can turn during all phases subject to giving way to conflicting vehicle movements as well as pedestrians crossing the slip lane For example in Figure 3 1 in Section 3 2 3 left turn movements using the slip lane on the East approach give way to through traffic from the North approach and the right turn traffic from the West approach 45 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Figure 6 7 T intersection phasing to demonstrate use of complementary left and right arrow controlled turns Phase A O O s O oe e pcs OO OO AN Phase B Phase C 46 AUSTROADS TZ TZ Accessed by AR M VICROADS on 02 Jun 2005 6 5 Pedestrian Movements 6 5 1 General a Control of pedestrian movements is achieved through
244. n movements see Figure 5 4 The green left turn arrow should be displayed only when no conflicting traffic movements vehicle or pedestrian are permitted The red left turn arrow should be displayed following the yellow arrow display when the left turn movement or a conflicting movement vehicle or pedestrian must be protected Vehicle movements include special vehicles such as tram bus or train The column of left turn aspects should be blacked out when the left turn movement may filter through a parallel walk or other traffic movement i e when the circular green only is displayed AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 5 5 2 Five Aspect Signal Face Layouts with Left Turn Arrow Aspects Left Turn Yellow and Green Arrow Aspects When it is not required to protect conflicting move ments during the display of the circular green the red left turn arrow aspect may be omitted from the six aspect face layout forming the five aspect signal face layout shown in Figure 5 17 The left turn green arrow should be displayed only when no conflicting traffic movements are permitted Left Turn Yellow and Red Arrow Aspects The yellow and red arrow aspects alone Figure 5 72 should be provided when the left turn movement may be stopped during the circular green display but the requirements for a left turn green arrow in Section 5 5 1 are not met This occurs infrequently but may be required to stop left turn traffic
245. n movements see Figure 5 4 The green right turn arrow should be displayed only when no conflicting traffic movements vehicle or pedestrian are permitted The yellow right turn arrow is always displayed follow ing the green arrow display The red right turn arrow should be displayed follow ing the yellow arrow display when the right turn move ment or a conflicting movement vehicle or pedest rian must be protected Vehicle movements include special vehicles such as tram bus or train 5 4 2 Five Aspect Signal Face Layouts with Right Turn Arrow Aspects Right Turn Yellow and Green Arrow Aspects A five aspect signal face layout with yellow and green arrow aspects as shown in Figure 5 7 may be used in lieu of a six aspect face layout when a the right turn movement may filter at all times when the circular aspect is green hence no need for red arrow and b there is no conflicting pedestrian movement or special movement which requires protection from the right turning vehicle see Section 6 3 Right Turn Yellow and Red Arrow Aspects A five aspect signal layout with yellow and red arrow aspects as shown in Figure 5 8 is rarely needed and is not permitted in some jurisdictions It may be used to terminate a right turn filter movement during the circular green display to avoid blockage of the inter section during a nearby tram bus or train movement 23 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SI
246. nalysis of signalised intersections include degree of saturation which is the ratio of arrival demand flow rate to capacity and flow ratio i e the ratio of arrival demand flow rate to saturation flow rate These parameters can be determined from Q sg c B 3 16 x q Q qc sg B 3 17 y q s B 3 18 where Q is capacity veh h s is the saturation flow rate g is the effective green time s c is the cycle time s and q is the arrival demand flow rate veh h Traffic flow conditions with demand flow rates below and above capacity are referred to as undersaturated and oversaturated conditions respectively AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 Akcelik Besley and Roper 1999 described analytical models for queue discharge and uninterrupted flow conditions at traffic signals The models were calibrated using data collected at eighteen signalised intersections in Sydney and Melbourne Table B 7 summarises the average parameter values for through and right turn traffic lanes at these intersections for light vehicles only The parameters for right turn lanes are for arrow controlled movements For data presented in Table B 1 average vehicle length was L 4 4 m and the effective detection zone length was L 745m Figures B 2 to B 4 show various relationships among the basic parameters based on the use of data given in Table B 1 for through traffic lanes As seen in Figure B 2 each vehicle spac
247. nce facility is available in the most recent microprocessor based signal controllers d Priority sequence This provides for the abrupt insertion of a phase into the sequence e g in response to a train tram or bus demand e Forced sequence This provides for a sequence of phases to be determined by a master controller and or external logic This facility is required in most coordinated and other master controlled systems 9 3 1 2 Display Duration Facilities a Fixed duration The duration of the display is fixed b Traffic actuated The duration of the display is determined by the actuations of the vehicle detectors and pedestrian push button detectors associated with that phase This facility is available in most controllers in various degrees of complexity c Traffic responsive The duration of the display is determined by the traffic demands on all approaches of the intersection This facility is not yet commercially available in isolated controllers d Master controlled The duration of the display is determined by signals commands from a master computer or other coordination devices AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 9 3 1 3 Coordination and Communication Facilities These facilities are determined by the coordination requirements and or area traffic control system such as SCATS Lowrie 1982 1990 1996 2001 within which the intersection must operate Some po
248. nces to be tested one or more showing vehicle opposed and unopposed and pedestrian movements which operate in each phase iii Timing data including intergreen times start loss and end gain times minimum and maximum green times pedestrian Walk and Clearance times iv Movements for green split priority for allocation of any excess green times in long cycles AUSTROADS APPENDIX D WORKED EXAMPLE v Phase green times and cycle time if data observed in the field or reported by SCATS or other control system are available for testing current traffic conditions under current signal timings vi Signal coordination data percentage arriving during green or arrival types describing progression quality d Movement Operational Data i Approach and exit speeds approach distances jam spacings ii Negotiation radius speed and distance for movements through the intersection iii Opposing movement specifications and gap acceptance parameters for opposed turns filter right turn and slip lane left turn movements iv Practical target degrees of saturation for signal timing and spare capacity calculations Software packages provide default values for most input data items representing commonly occurring conditions These default values can be used where data are not available D 2 2 Output Information Various output statistics for timing and performance analyses of signalised intersections are pre
249. nctions and can be adopted to intersections with more than four approaches Each phasing element is discussed in detail in Sections 6 3 1 to 6 3 7 37 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Movement symbols used in Figure 6 7 and the phasing diagrams given in this guide do not have any lane use implications i e through right turn and left turn movements are shown separately irrespective of being in shared or exclusive lanes Any movements stopped by red displays are not shown in the full phase sequence diagrams Turning movements that give way to opposing vehicle or pedestrian movements are shown in broken lines The phasing alternatives shown in Figure 6 7 are named by the type of right turn movement operating in the phasing sequence since generally right turn movements determine phasing requirements Phasing requirements for left turn and pedestrian movements are discussed in Sections 6 4 and 6 5 The basic phasing elements in Figure 6 7 show move ments on one road only say East West road Left turn Figure 6 1 Definitions of basic elements of signal phasing left turn and pedestrian movements not shown for clarity Through with filter right turns Leading right turn Lagging right turn Split approach Diamond overlap Lead lag right turn Repeat right turn lt lt _ gt 1 NRT No Right Turn right turn movement must be banned whe
250. nd West approaches do not include any arrow controlled turning movements the basic three aspect signal display is used However as the signal faces for the North approach are required to provide for a leading right turn phase a six aspect multi column signal face is used This consists of a column of three aspect green yellow and red right turn arrows in addition to the basic three aspect signals see Figure 5 4 This operation could also be implemented using a five aspect two column signal face with green and yellow right turn arrows only see Figure 5 7 In the case of three aspect right turn arrows red arrow drop out method is used to achieve filter right turns in Phase A as allowed by the adjacent green circle displays see Section 6 3 Figure D 13 Signal face locations for Design 2 m 2 8 3 4 3 2 3 4 3 0 C l C A C A ONE E N b B B file 3 0 B Wa A E e 23 d B un 32 Lys B 32 EM 32 Ves B Jw IE ye 5 o ESP te B 4 cM e 35 a cal D E Controller 9 A 3 4 3 2 3 4 Signal post numbers AUSTROADS 147 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS b Number of Signal Faces c Size of Signal Aspects i East and West approaches Three signal faces Only 200 mm aspects are used as recommended primary secondary and tertiary are provided in Section 5 2 3 since there are no grounds for The green circle is display
251. ning right from internal approaches to the freeway on ramps a Staggered T intersection Figure 15 6 Examples of staggered T intersection and freeway diamond interchange AUSTROADS 103 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 15 9 3 Intersections With More Than Four Legs At intersections with more than four legs potentially there are more than four origin destination movements from each approach road The design of lane arrange ments Section 3 and signal phasings Section 6 for such intersections is a significantly more complex task Where allowed U turn movements will also need to be considered in the design Refer to AS 1742 Part 14 Section 6 2 3 Generally these complex intersections would be treated on a site specific basis An example of a five way intersection geometry and phasing arrangements is shown in Figure 15 7 The complexity of signal design for such intersections depends on the number of conflicting vehicle move ments The main aim is to minimise the number of phases as much as possible by eliminating some of the conflicting movements This may mean banning some movements by using regulatory signs introducing one way approach and one way exit conditions or intro ducing partial or total road closure Where movements are banned alternative routes should be available and may need to be signposted as such In Figure 15 7 the East
252. nly be used in green aspects when absolutely necessary Where all traffic on an approach must turn left and or right and there is no conflict with a pedestrian or other traffic movement extra guidance may be given by replacing green circular aspects with arrows Downward pointing arrow aspects should not be used with intersection control signals their use is confined to overhead control signals Pedestrian Aspects The Don t Walk aspect is a red standing human figure and the Walk aspect is a green walking human figure as seen in Figure 5 1 Bicycle Aspects Where regulations permit bicycle aspects can be used in a similar way to pedestrian aspects to control cyclists crossing the road or in a similar way to vehicle aspects to control on road bicyclists at an intersection The symbol for bicycle aspects is shown in Figure 5 1 Two aspects red and green are used for road crossings Three aspects red yellow and green are used at road intersections with exclusive bicycle lanes or at inter sections of a road and exclusive bicycle path Special Vehicle Aspects Special vehicle aspects are used to control bus tram and emergency vehicle movements at traffic signals as regulations permit The symbols for special vehicle aspects are given in Figure 5 1 AUSTROADS The white T or B and in some jurisdictions E aspect is used to indicate that trams buses or emergency vehicles may proceed White arrows are also used occ
253. ns distances destinations routes and location of services for road users and points of interest Headway The time between passage of the front ends of two successive vehicles corresponds to Spacing Not to be confused with the Headway Setting in a signal controller Headway Setting A controller setting equivalent to a predetermined space time measured between successive vehicles at the given saturation or queue discharge speed detection zone length and vehicle length values Also see Space Time Intensity see Luminous Intensity AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 Intersection A place at which two or more roads meet or cross Intergreen Time Duration of the clearance part of the phase corres ponding to the period between the phase change point the end of running intervals and the beginning of the green display for the next phase end of phase Normally it comprises Yellow Time and All Red Time The Early Cut off Green interval that follows the phase change point is also considered to be part of the Intergreen Time Irradiation Blurring of the edges of a bright object viewed adjacent to a dark background Junction see ntersection Lagging Right Turn An arrow controlled right turn movement that is started and terminated in the phase that immediately follows the phase in which the opposing through movement runs Lane A portion of the carriageway allocated for the use of a single line
254. ns given in Section 6 5 2 e Figures 7 9 b and 7 9 c in Section 7 show midblock two stage signalised crossings with an offset Pedestrian sensors may be used to detect pedestrians waiting to cross the road as well as pedestrians who are on the crossing so as to provide variable length clearance interval for pedestrians e g Puffin crossings see Section 8 4 1 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 7 Location of Signal Equipment 7 1 Introduction Signal face layouts are discussed in detail in Section 5 This section discusses location of signal equipment within the area of the intersection including location of pedestrian signal faces Signal faces should be located in accordance with specification in AS 1742 Part 14 Standards Australia 1996 Location of pedestrian push button assemblies is discussed in Section 8 4 3 7 2 Designation of Signal Faces The designation of signal faces in relation to their locations for a given approach road are given below and shown in Figures 7 1 and 7 2 for i an undivided road approach at a cross road intersection ii a divided road approach at a cross road intersection iii a terminating road at a T intersection and iv an approach road at a midblock signalised crossing Various symbols used in figures given in this section to describe signal faces are explained in Figure 7 3 Refer to AS 1100 Part 401 and local standards for additional symbols Pri
255. nsportation Research Center University of Florida Gainesville Florida U S A LOWRIE P 1982 The Sydney Coordinated Adaptive Traffic System principles methodology algorithms Proc International Conference on Road Traffic Signalling Institution of Electrical Engineers London pp 67 70 LOWRIE P 1990 SCATS A Traffic Responsive Method of Controlling Urban Traffic Roads and Traffic Authority of New South Wales Sydney LOWRIE P 1996 Signal linking and area control In Traffic Engineering and Management Eds K W Ogden and S Y Taylor Institute of Transport Studies Department of Civil Engineering Monash University Melbourne Australia Reprinted 1999 pp 461 480 LOWRIE P 1996a Freeway Ramp Metering Systems Paper presented at the TE Inaugural Regional Conference Transport and Liveable Cities Melbourne Australia AUSTROADS REFERENCES LOWRIE P 2001 SCATS The history of its development Paper presented at the 8th World Congress on Intelligent Transport Systems Sydney Australia Paper No ITS00738 Session No 147 CD LUK J SIMS A G and LOWRIE P 1983 Parramatta Experiment Evaluating Four Methods of Area Traffic Control Research Report ARR No ARR 132 ARRB Transport Research Ltd Vermont South Australia McGINLEY F J 1983 Active tram priority in co ordinated signal systems Australian Road Research 13 3 pp 173 184 MIDDLETON I J 1969 Study of Acci
256. ntersections controlled by give way or stop signs is an unusual application and can only be applied where local traffic regulations permit The system is similar in operation to roundabout metering signals Section 15 7 However it is only recommended for local urban collector roads where the posted speed limit is 60 km h or below The objective of the system is to reduce excessive delays experienced by sign controlled movements that have difficulty in finding adequate gaps in priority traffic streams As an alternative to full signalisation the metering signals are employed on a part time basis at sites where they are required only during peak demand periods This arrangement consists of two aspect yellow and red signals see Figure 5 6 a in Section 5 3 4 for metering the major road traffic and a queue detector Section 8 3 4 3 to detect vehicles waiting on the sign controlled approach The sequence of aspect display is Off to Yellow to Red to Off When metering is not required metering signals facing the major road traffic are in Off state blank display When the queue detector on the approach subject to sign control detects vehicles waiting the metering signals display Yellow and then Red When the Red display is terminated on the major road the intersection reverts to normal operation In one jurisdiction two aspect yellow and green displays were used on the sign controlled approach In this case the display sequence wa
257. ntial point of conflict with vehicle and pedestrian traffic of the next phase the length of the clearing vehicle and the time for starting traffic to reach the furthest point of potential conflict with vehicles or pedestrians A detailed method to take these factors into account was described by Hulscher 1980 The following simplified method is recommended for determining the All Red Time t 36L v C 4 3 subject to t 1 0 where t All Red Time s L clearance distance between the stop line and furthest point of potential conflict with vehicles or pedestrians of the next phase m and vp design speed km h The All Red Time values calculated as a function of speed for various clearance distances are shown in Figure C 5 While there may be isolated instances when longer All Red Times are justified to meet unusual traffic situations additional All Red Time must not be provided to clear any vehicles waiting to make a right hand turn Exces sive All Red Times are likely to give rise to running the red behaviour particularly if yellow times are too short Special All Red setting for a phase is used for phase transitions that require significantly longer or shorter all red values e g due to phase skipping compared with the all red setting for normal phase transition C 4 7 Other Vehicle Settings C 4 7 1 Presence Setting This is used to set the time for which a detector must be occupied before a demand i
258. number of closely spaced signals interconnected by a cable usually with one of the signal controllers assuming the role of master Also see Master Controller Louvres An assembly of mechanical baffles mounted within the visor to reduce sun phantom horizontal louvres or to restrict the angular coverage of a signal vertical louvres Luminance Luminance at a point of a surface and in a given direction is the luminous intensity per unit projected area of a light emitting or reflecting surface Luminous Intensity Luminous intensity in a given direction is the luminous flux emitted by a light source in an infinitesimal cone containing the given direction divided by the solid angle of that cone Marked Foot Crossing A transverse strip of carriageway marked for the use of pedestrians crossing the road mid block or at an intersection controlled by vehicular and pedestrian signals The term Signalised Crossing used in this docu ment includes Marked Foot Crossing Masterlink The fully adaptive mode of operation of the SCATS control system Median A dividing strip that separates vehicles travelling in opposite directions xix Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Master Controller A traffic signal controller controlling a system of sec ondary controllers Movement A stream of vehicles that enters from the same app roach and departs from the same exit i e with the same origin and destination
259. oads An unbroken dividing line may be a single unbroken line or a parallel pair of unbroken lines Both types of dividing lines prevent overtaking A single unbroken line may be crossed to enter or leave the road but a parallel pair of unbroken lines may not be crossed to enter or leave the road unless a local jurisdiction road rule permits Normally dividing lines should be provided for a minimum of 30 m in approach to the stop line see Section 10 3 1 This length may be extended if road conditions on an intersection approach require it 10 2 2 Lane Lines On the immediate approaches to traffic signals the use of lane lines is essential where the approach width will accommodate two or more traffic streams Lane lines are generally broken lines but must be unbroken where lane changing is to be prohibited on the approach 10 2 3 Turn Lines Turn lines are used to provide guidance for two or more traffic streams turning in the same direction Turn lines are not used for single turning movements unless in their absence opposing right turns would be in danger of colliding or the turning path to the departure is not obvious under all conditions Where opposing right turn movements operate in the same phase care must be taken with positioning turn lines so that sufficient swept width is provided for each vehicle and a sufficient gap is left between opposing turning traffic The use of Austroads turning path templates can assist w
260. od The Flashing Don t Walk period that immediately follows the termination of pedestrian Walk display to enable pedestrians who have just stepped off the kerb at the commencement of this period to complete their crossing to the nearest kerb or refuge Pedestrian Clearance Time is the duration of the Pedestrian Clearance Period AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 Pedestrian Crossing A transverse strip of carriageway marked for the use of pedestrians crossing the road mid block or at intersections at a place with a pedestrian crossing sign and with or without alternating flashing twin yellow lights Also called Zebra Crossing where indicated by parallel white stripes on the road surface Pedestrian Green Time The duration of the green Walk display Pedestrian Indicator An indicator mounted on the pedestrian push button assembly that is illuminated to acknowledge when a demand has been recorded Pedestrian Push Button Assembly Device to enable pedestrians to register a demand for right of way It includes the pedestrian indicator Push button devices are also used for bicycles and emergency vehicles Pedestrian Refuge A place usually in a carriageway set aside for exclusive use of pedestrians Pedestrian Signal Face A two aspect signal face for the control of pedestrian movements that consists of green Walk and red Don t Walk aspects Also see Pedestrian Aspects Perception and Reaction Time The
261. of green time available to a platoon along a route Figure 13 1 a shows a time distance diagram for an idealised situation where the green times on the arterial approaches of all intersections are equal and good progression is provided in both directions Unequal green times and different spacings between inter sections make it difficult to achieve coordination in both directions of a route or on all directions in a network Figures 13 1 b and 13 1 0 illustrate the starting offset and finishing offset strategies for one way progress ions respectively In these cases the value of offset equals the average travel time based on the design progression speed The aim of a starting offset strategy is to provide minimum stops The lead vehicles are presented with green signals before they reach each intersection in order to achieve smooth progression There may be however a penalty for vehicles towards the rear of the platoon At those intersections where less green time is available to the through phase all vehicles may not have cleared the intersection before the phase is terminated Consequently the trailing vehicles will be stopped forming residual queues These vehicles must then wait until the next cycle and experience delays and may also interfere with the progression of the platoon from the next cycle By coordinating finishing offsets minimum delay can be achieved since few vehicles travelling on the arterial route will be
262. of the kerb lines unless a signalised crossing is provided and e f when a signalised crossing is provided the median should be terminated at the crossing unless a gap in the median as wide as the crossing is provided and the median continued for at least 2 m beyond the crossing 3 4 2 Undivided Roads with Small Median Islands at the Intersection The practices listed in Section 3 4 1 for divided roads also apply to sites with minor channelisation The median islands should be at least 10 m long to ensure adequate conspicuity If a signal post is provided the median should be at least 1 2 m wide for single column lanterns wider for two column lanterns 3 5 Painted Medians and Islands Painted medians or islands may be used where there is not sufficient carriageway width to construct a kerbed median or island or where it is desirable to permit vehicles to cross the median Painted medians may be used with painted five lane intersection treatments in urban areas as shown in Figure 3 1 For this treatment lane widths on a four lane undivided road are reduced in the vicinity of the intersection to permit the creation of a separate sheltered right turn lane Viability of this treatment depends on being able to achieve accep table lane widths See Austroads GTEP Part 5 Traffic signal posts should not be placed in the painted areas and they should always be located behind raised kerbing see Section 10 4 11 Acces
263. of traffic a vehicles generally b pedestrians c special vehicles i e buses trams bicycles emergency vehicles fire engines ambulances and trains Detection methods used for these types of traffic are discussed in the following sections 61 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 8 3 Vehicle Detection 8 3 1 Detector Types To satisfy the normal requirements of intersection control detectors must have a clearly defined detection zone so that interference from adjacent lanes is low Detectors that emit a broad beam of energy e g micro wave and infrared detectors fail to satisfy this criterion Currently the best type of detector that meets the detection requirements discussed in Section 8 1 2 is the inductive loop detector Although there are other types of detectors that satisfy these requirements they are generally operationally or economically inferior in normal situations and are not considered further Inductive loop detector systems vary mainly in the specification of detector location and size Abnormal situations or temporary detection require ments during road works or situations of road surface instability may be satisfied by use of microwave detector units Video image processing has found increased use over seas in recent years 8 3 2 Detection System Functions Vehicle detectors provide the following functions on a lane by lane or approach basis 8 3 2 1 Dem
264. ol computers usually by leased data lines or in some cases by dedicated cable systems Yellow Time Duration of the yellow display for a phase or a movement Yellow Trap see Right Turn Trap Zebra Crossing see Pedestrian Crossing XXV soog unf Zo uo SQVOHOIA W HV q pesseooy Accessed by AR M VICROADS on 02 Jun 2005 1 Introduction 1 1 General It is not practicable to standardise the design of inter sections or the signal installations that control them However to ensure uniformity it is important to stan dardise design procedures and the operating character istics of traffic signals This guide deals mainly with the design of traffic signals Traffic signal design can vary from simple two phase to very complex phasing control Signal phasing mainly depends on safe operation the volume and direction of traffic flows and intersection geometry Coordination can also affect signal phasing To ensure safe operation the signals roadway signs and pavement markings should provide consistent operating characteristics and be adequately maintained The design installation operation and maintenance details given in this guide needs to be tempered by the requirements practices and regulations of individual jurisdictions The guide presents general guidelines for design of signals and good engineering judgement is required for effective design to resolve issues that may arise in specific situations 1 2 Scop
265. om each approach to operate simultaneously Staged Signalised Crossing A system by which a long signalised crossing is divided or staged into several time separated sections each being a separate group controlled by individual signals Start Loss Duration of the interval between the start of displayed green period and the start of effective green period for a movement This is used in signal timing and perfor mance analysis to allow for queue discharge time losses at the start of green period due to vehicles accelerating to saturation speed or due to giving way to opposing vehicle or pedestrian movements Late Start time can be treated as a start loss for the movement that starts after the Late Start interval Also see End Gain Starting Display see Starting Signal Starting Offset Coordination Coordination of the start times of green periods using a signal offset that equals the average uninterrupted travel time in the travel direction so as to minimise stops along the route Also see Offset Starting Signal A signal which is located so that the drivers who have stopped at the stop line can see the signal display Stop Line A single continuous line double continuous lines in New Zealand known as limit line marked across all or part of a road behind which vehicles should stand when required to stop by traffic light signals or regulatory signs Also see Give Way Line Stopping Display see Stopping Signal Stopping
266. omic life of equipment and when replacement should be scheduled AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 15 Special Applications and Facilities 15 1 Introduction This section presents information on functional and operational aspects of special traffic signal applications and facilities For further information refer to AS 1742 Parts 2 and 14 15 2 Advance Warning Signals Advance warning signals are an active warning device consisting of a warning sign with Alternating Flashing Yellow lights Alternative formats for advance warning signals are shown in Figure 15 1 The advance warning device is cabled to the traffic controller and timed as a separate signal group The yellow lights should flash alternately one being Off while the other is On at a frequency of 1 Hz There are two main purposes for the use of an active advance warning device rather than a passive device a Arterial roads with a high proportion of heavy or long combination vehicles where there is a high risk of frequent infringement of signals and a high risk of rear end and cross accidents due to the inability to stop in time for the red display e g due to high approach speeds or significant PW 64 should be used W8 27 sign Figure 15 1 Alternative formats for advance warning signals Note the two alternatives shown on the right hand side of the diagram are not permitted in New Zealand where MOTSAM sign Alternate
267. on a lane or carriageway during a specified period of time Also see Demand Flow Demand Volume Flow Rate Traffic Count Trailing Right Turn see Lagging Right Turn Transponder A device fitted to a bus tram or emergency vehicle that allows the signal controller to selectively identify the presence of that vehicle in a stream of mixed traffic Undivided Road A road without a median Also see Divided Road Unopposed Turn A left turn or right turn movement at a signalised intersection that is made with no opposing or conflicting vehicular or pedestrian flow allowed Upstream In the direction opposite to the movement of traffic Urban Traffic Control System see Wide Area Control System AUSTROADS GLOSSARY Vehicle Actuated Control see Traffic Actuated Control Vehicle Passage Time The time between the passage of the front and back ends of a vehicle from a given point along the road Visor An attachment to the face of a signal aspect to minimise the sun phantom effect and or to reduce the possibility of a signal being seen by traffic for which it is not intended Also called Cowl Volume of Traffic see Traffic Volume Walk Time Duration of the Walk display steady green person for pedestrians Wide Area Control System A signal coordination system comprising one or more centrally or regionally located computers controlling relatively large numbers of signals with all signals connected to the traffic contr
268. on of Controller Housing and Signal Posts in Phase A only The controller should be located in an unexposed iv Pedestrian signals Only one pedestrian position in close proximity to the intersection signal face is required at each end of the and available power supply In Figure D 13 signalised crossing as the crossing width and this is located on the South West corner distance criteria are satisfied see Section 7 4 4 Note that the East West crossing The posts are numbered sequentially 1 to 10 in a clockwise manner for the identification used Pedestrian signal faces display green Walk in the cable connection diagram Note that the signal during the appropriate phases C A number of posts has been minimised by accommo A or B see Figures D 7 and D 13 dating the various signals where practicable on a common post distance is close to the limit value of 25 m Figure D 14 A typical cable layout diagram for Design 2 Post number Cable 9 3 Cable 8 8 Cable 7 O Cable 6 Cable 5 8 B o et Dm 5 A amp Le E yj U Det Feeder cable Conner Cable 1 Cable 2 Cable 3 Cable 4 B Q Post D number se e Det C A An optional cable can be added between Posts 4 and 5 This cable is available to restore the service quickly in the event of a breakage elsewhere in the loop 148 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 D 5 2 Cable Connection Design The cable layout for the in
269. on t Walk Green amp Red Green amp Yellow Yellow amp Red Green amp Yellow amp Red ix ix No Walk amp No Don t Walk X Acceptable display I Undesirable display Unsafe display Ld Acceptable display where 1 shown during intergreen or for intervals not exceeding 4 seconds 2 multiple relay failures occur 3 the Off signal group has the majority of its displays on the same post s as the signal group which displays the colour Red 72 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 10 Pavement Markings 10 1 General This section provides information on pavement mark ings used at signalised intersections It contains addit ional and supplementary data to that contained in AS 1742 Part 2 and AS 1742 Part 14 and Austroads GTEP Part 5 Intersections at Grade In New Zealand reference should be made to the Manual of Traffic Signs and Markings Part Il Transit New Zealand and Land Transport Safety Authority 1997 Pavement markings at traffic signal installations are subject to constant wear by turning and braking traffic and they are often obscured by general traffic There fore they must be properly maintained for effective and safe operation of signals 10 2 Longitudinal Lines 10 2 1 Dividing Lines Unbroken dividing lines are marked on the roadway to separate opposing traffic movements on the approaches to signalised intersections and midblock signalised crossings on undivided r
270. on the South approach are specified D 3 2 Analysis Results for Design 1 With the default actuated signal settings an average cycle time of 102 s is estimated with green times of 50 s for Phase A maximum and 40 s for Phase B Highly oversaturated conditions and therefore very AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 long delays level of service F are predicted for the filter right turn movement from North as seen in Figures D 4 and D 5 All other movements appear to operate satisfactorily with the exception of right turn from South level of service E From Figure D 5 the right turn lanes on North and South approaches are seen to be operating as de facto exclusive lanes right turns only due to long delays experienced in these lanes This indicates inefficient use of the road space available Optimisation of cycle time as coordinated actuated signals indicates that the performance of right turn movements can be improved significantly at an opti mum cycle time of 84 s green times of 46 s for Phase A and 26 s for Phase B However the right turn move ment from the North approach is still highly over saturated average delay 322 4 s Furthermore the coordination requirements may not allow the use of a shorter cycle time These results confirm the need for improvements to the intersection layout and signal phasing to cater for the right turn movement from the North approach in particular APPEND
271. ons without kerbing on high speed approaches 3 m to 5 m clear from the nearest point of conflict with cross traffic and upstream of the primary traffic signals c d Midblock Signalised Crossings nominal 6 m in advance of crossing but not less than 10 m in advance of secondary signal 10 3 2 Pedestrian Crosswalk Lines The signalised crossing should be at least 2 m wide and delineated by two parallel lines This width should be increased when there are heavy pedestrian volumes The line nearest the centre of the intersection should be not less than 0 6 m desirably 1 0 m clear of the cross street kerbline projection For scramble crossings Section 11 3 4 the lines nearest the centre of the intersection are removed and in some jurisdictions diagonal lines connecting opposite corners of the controlled area are used Signalised crossings should generally follow the shortest route across the carriageway or be angled at no more than 20 degrees to the pedestrian s shortest route Pedestrian Zebra crossings defined by parallel white stripes on the road surface and two Walking Legs signs Section 11 3 14 are not used within the control led area of signalised intersections However some juris dictions use Zebra crossings at unsignalised slip lanes at signalised intersections 10 4 Painted Medians and Islands Painted areas see Section 3 5 may be line marked to prevent or permit vehicles to cross the a
272. onsidered in the overall design Benefits to public transport may be achieved by either introducing a passive bias to the signal settings or by actively responding to the presence of a public transport vehicle to adjust the signal operation It may also be possible to relocate bus or tram stops at certain critical points 89 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 13 8 Coordination Timing Criteria As discussed in Section 13 7 the principal objective of coordination timing is to optimise a selected perfor mance measure Usually delay number of stops or a combination of delay and stops is used as the perfor mance measure It is generally recognised that the following factors favour minimising stops a crash risk this is greatest at the change of signal phases and is reduced if fewer vehicles are stopped b fuel consumption exhaust pollution and operating cost these are increased by stop start driving cycles therefore reduced if fewer vehicles are stopped c driver expectation drivers relate coordination more to the number of stops than to overall delay Minimising the number of stops fuel consumption emissions or operating cost does not yield the same signal timing plans as the minimum delay criterion due to the different offset and cycle time requirements However as shown in Figure 13 3 such longer cycle times do not involve a significant delay penalty On the other hand long cy
273. ontribute to the achievement of improved Australian and New Zealand transport related outcomes by e developing and promoting best practice for the safe and effective management and use of the road system providing professional support and advice to member organisations and national and international bodies acting as a common vehicle for national and international action e fulfilling the role of the Australian Transport Council s Road Modal Group e undertaking performance assessment and development of Australian and New Zealand standards developing and managing the National Strategic Research Program for roads and their use Within this ambit Austroads aims to provide strategic direction for the integrated development management and operation of the Australian and New Zealand road system through the promotion of national uniformity and harmony elimination of unnecessary duplication and the identification and application of world best practice Austroads Membership Austroads membership comprises the six State and two Territory road transport and traffic authorities and the Commonwealth Department of Transport and Regional Services in Australia the Australian Local Government Association and Transit New Zealand It is governed by a council consisting of the chief executive officer or an alternative senior executive officer of each of its eleven member organisations e Roads and Traffic Authority New South Wales e Roads Corporatio
274. ordination of traffic signals is implemented to improve the level of service of a road or a network of roads where the spacing of signals is such that isolated operation causes frequent stopping and unnecessary delays to platoons of vehicles formed at upstream signals Signal coordination also helps to prevent queues forming at a downstream intersection extending back and reducing the capacity of an upstream intersection particularly where there is limited queue storage space between intersections Ak elik 1981 Lowrie 1996 Signal coordination is accomplished essentially by a operating all signals in the area on the same system cycle time and b maintaining a time offset relationship between start or end times of green displays at adjacent upstream and downstream signals according to the speed of vehicle platoons so as to obtain a progression of green periods along the road An exception to the use of common system cycle time is double cycling see Section 13 2 1 The design objective in determining a signal coordi nation plan the system cycle time durations of green displays and offsets is to optimise a selected perfor mance measure e g minimise delay or the number of stops or a combination of delay and stops The perfor mance measure can be applied for the area as a whole or for selected routes in the area e g major arterial roads Signal coordination is an important tool in the achieve ment of other traff
275. out stopping during the associated intergreen period s Also see Overlapping Signal Group Overlapping Signal Group A signal group that displays green in consecutive phases and during the associated phase transition s Also see Overlap Movement Painted Island An area of a road surrounded by a line or lines whether broken or continuous on which there are stripes marked on the road surface in white or another colour contrasting with the colour of the road Parallel Pedestrian Movement A signalised pedestrian movement that runs at the same time as the parallel vehicle movement s that are controlled by circular green displays Partial Control Control of a turning movement by a green arrow display in one phase as an unopposed movement and by a green circle display in another phase as a filter or opposed movement Passage Detector A detector which produces a short output pulse of relatively constant duration independent of the mass or type of a moving vehicle within the detection zone Peak Period The period that has the highest demand volume of traffic during the day peak hour peak half hour etc Also see Off Peak Period Pedestrian Actuated Control see Traffic Actuated Control Pedestrian Aspects Signal aspects for pedestrians consisting of the Walk aspect a green walking human figure and the Don t Walk aspect red standing human figure Also see Pedestrian Signal Face Pedestrian Clearance Peri
276. ovided adequate sight distance is available an overhead secondary signal face may be used instead of an overhead primary signal face where additional starting and or manoeuvring functions are required e g if secondary median signal faces are not available or for additional right turn arrow aspects when dual primary signal faces are not available Where two overhead signal faces are required for each approach primary and secondary signal faces for opposite approaches are often mounted on the same mast arm to reduce costs AUSTROADS LOCATION OF SIGNAL EQUIPTMENT c Provided adequate sight distance is available an overhead tertiary signal face may be used instead of an overhead primary signal face when additional starting or manoeuvring functions are required e g for additional signal faces incorporating left turn arrows d Provided signal face functional requirements are met see Section 7 3 economy in the use of mast arms can be achieved by mounting more than one signal face on a mast arm e g on cross road inter sections a primary signal face for one approach and a tertiary signal face for the approach from the right Unless obstructions such as power lines are present the mast arm outreach selected should ideally locate the signal face above the second lane from the kerb e Where obstructions are present and inadequate sight distance is the main reason for providing an overhead signal face
277. permit filter turns after a few seconds in the through phase Red Time Duration of the red signal display for a phase or a movement Also see Effective Green and Red Times Repeat Right Turn Phasing Phasing that introduces the arrow controlled right turn twice in the same cycle Reversible Lanes see Tidal Flow Scheme Right Turn Trap A situation where a driver executing a filter right turn manoeuvre at the start of yellow interval thinks that the signals change to yellow for the opposing traffic at the same time and therefore proceeds and runs into an opposing through vehicle for which the signal display would still be green Also known as lagging right turn problem or yellow trap Also see Lagging Right Turn Road Marking A word figure symbol mark line raised marker or stud or something else on the surface of a road to direct or warn traffic but does not include a Painted Island SCATS A well known fully adaptive wide area control system developed in Australia and used in many cities around the world Sydney Coordinated Adaptive Traffic System SCATS DS Degree of saturation in the SCATS adaptive control method SCATS Master Isolated Control The SCATS adaptive control method for a single isolated signalised intersection Scramble Crossing Phase An Exclusive Pedestrian Phase at an intersection where pedestrians are allowed to cross in any direction including diagonally within the limits of the crosswalk
278. plan intro duction times are modified or selected by comparison of measured traffic parameters usually flow and or occupancy with predetermined levels of these para meters Typically these parameters are derived from 88 data measured on a limited number of detectors located so as to capture predominant characteristics of known traffic conditions This mode of operation offers flexibility in plan intro duction times but suffers from most of the problems of fixed time system and cannot allow for unpredicted demand patterns in a satisfactory way 13 5 3 Fully Adaptive System Fully traffic responsive control employs a large number of vehicle detectors usually at every controlled signal Two such systems that have been widely accepted are SCOOT Hunt et al 1981 and SCATS e g Lowrie 1996 2001 The adaptive mode of operation of SCATS is known as Masterlink SCATS also provides for a fall back cableless linking mode known as Flexilink which is used to maintain a level of signal coordination in the event of failure of the regional computer or parts of the communication system Section 13 4 2 A fully adaptive system generates appropriate signal timing plans on line in a continuously variable fashion using the extensive traffic flow and density data provided by vehicle detectors As a result signal timing plans can suit a wide variety of traffic conditions responding to wide variations in demand pattern and changes in netwo
279. quate kerbside parking controls or unfore seen variations in traffic demand flow are examples of problems that may be identified When a signalised intersection is commissioned users may experiment with alternative routes during the fine tuning period Thus the timing of the monitoring and evaluation process needs careful consideration The pro cess may need to be repeated a number of times While the design may be based on selected peak traffic flows see Section 2 3 monitoring and evaluation should also consider conditions during off peak periods public or school holidays and unusual traffic flow periods The monitoring and evaluation process essentially repeats the design process using the data collected after the commissioning to verify the adequacy of the design in terms of safety and efficiency If deficiencies are evident it may be possible to implement changes to improve performance e g fine tuning of signal timings phase sequencing restrictions on movements and extension of kerbside controls In some cases deficiencies can only be corrected by a complete redesign of the channelisation associated with the signal installation particularly when the design has been constrained The decision to implement a redesign involves a complex process of engineering assessment 14 2 2 Check List The following checks should be made when monitoring and evaluating the operation of a site a are the signs and road markings
280. quipment is correctly installed and are in accordance with the design plan operating h check signal faces for correct aiming and coverage by visual inspection from each 14 1 2 Check List approach lane see Section 7 5 The following checks should be carried out i check signal visors and louvres to ensure that sun phantoms are acceptably low and that signal cut off in relation to conflicting movements has been achieved see Sections 7 6 and 7 7 a ensure that an insulation check in accordance with AS NZS 3000 has been completed prior to switching on the controller and detectors generally the relevant electricity supply authority will not check that the flashing yellow mode and start up provide connection to mains supply unless their sequence operate correctly special requirements and those of AS NZS 3000 k with lamp switching circuits energised check have been met the operation of the signal groups by cycling b ensure that the controller has been tested in the the controller through all of its phases this is a workshop for compliance with the controller further check that the controller programming programming procedures Section 9 4 and applied to the site is correct phasing requirements of the design I check that the site communicates to the central c check vehicle detectors for correct operation computer if applicable presence or passage and ensure that the loop m check that any necessary changes to the design
281. r 2 C A2 detectors detailed below Phase B approach timer 1 B1 detectors a All detectors are 4 5 m presence detectors Phase B approach timer 2 B2 detectors located at the stop line in each lane except Phase C approach timer 1 C A1 detector for the C phase right turn detector which is approach section an 11 0 m detector because both an arrow controlled turn and a filter turn are provided see Figure D 15 also Figure 8 3 in Section 8 c Pedestrian features will be as follows Individual detector loops are labelled for Pedestrian feature number 1 C A pedestrian identification purposes Method of labelling varies from jurisdiction to jurisdiction and Phase C approach timer 2 C A2 detectors Pedestrian feature number 2 A pedestrian may reflect detector operational functions Pedestrian feature number 3 B pedestrian Figure D 16 Phase and pedestrian time settings recorded in a typical Timing Card for Design 2 Controller Time Settings Phase Time Settings Time Phase Setting B C D E F G No Description Limit 1 2 3 4 5 6 7 1 RED YELLOW 5 5 2 LATE START 20 5 3 MINIMUM GREEN 20 8 8 6 4 INCREMENT 5 gt 5 MAXIMUM INITIAL GREEN 40 6 MAXIMUM EXTENSION GREEN 90 27 27 8 7 EARLY CUT OFF ECO 20 8 YELLOW 7 5 0 4 0 4 0 9 ALL RED 15 1 0 2 0 2 0 10 SPECIAL ALL RED 15 11 GAP 1 10 2 5 2 5 2 0 12 GAP 2 10 2 5 2 5 2 5 13 GAP 3 10 gt 14 GAP 4 10 gt 15 HEADWAY 1 5 0
282. r boundaries for red green and yellow signals apply to a four colour system the fourth colour being white As stated previously it is important to maintain AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 the maximum separation between colours to allow for colour vision defect At the same time the boundaries of the red and green signals should be chosen away from the extremities of the visible spectrum where the sensitivity of the eye is reduced and much higher signal intensities would be required to satisfy the criteria outlined in Section A 3 1 Colour and signal intensity are significantly interconnected and in practice red signals are chosen as close as possible to the yellow boundary of the chromaticity diagram while green signals are selected as close as possible to the white boundary for maximum light output A 3 4 Photometric Requirements of Signals The photometric requirements of signals cover not only the intensity distribution of the coloured light and the colour boundaries but also the amount of sun phantom and size of target boards AUSTROADS APPENDIX A HUMAN FACTORS Cole and Brown 1968 determined the actual intensity for rapid perception of a red signal The standard has been set by the criterion of 200 cd of red light at a distance of 100 m This distance is equivalent to a stopping distance from a speed of 80 km h under dry conditions or 65 km h under wet conditions Fisher 1971 developed a spe
283. r right turn traffic lanes Using a limiting speed value of v 5 km h shorter optimum loop length values are determined 120 On this basis the optimum loop lengths were in the range 3 0 to 3 8 m for through traffic lanes and 2 2 to 3 1 m for right turn traffic lanes The saturation space time t is useful for determining appropriate gap settings for actuated signal control see Appendix C Section C 4 4 and for obtaining information about green time utilisation Average values of t 1 0 s for through traffic lanes and 0 5 s for right turn traffic lanes are given in Table B 1 An average space time during a signal cycle that exceeds the saturation space time indicates that the green time is not fully saturated This principle is used in SCATS to determine the degree of saturation DS for each cycle by comparing the total space time measured in each cycle with the space time at maximum flow MF Lowrie 1982 1990 1996 2001 An important advantage of the space time parameter for traffic control purposes is that unlike the headway and occupancy time parameters it is independent of the vehicle length Assuming that the gap length is not affected by vehicle type to a great extent the above considerations are valid irrespective of the vehicle type AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 Appendix C Signal Timings C 1 Introduction Allocation of appropriate green times to competing traffic movements at a
284. re opposing through movement overlaps 1 Both filter right turns may be allowed gt 2 Filter right turns from Aic approach opposite NRT may be allowed 3 3 Leading turn must be L fully controlled and NAT gt y lagging turn may be allowed to filter 38 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 and pedestrian movements are not shown for reason of clarity The leading lagging and repeat right turn phasing options are shown in terms of the right turn movement from the West approach but they are equally applicable to a right turn movement from the East approach Similarly the split approach and the lead lag phasing options can be in reverse order i e East approach first The phasing elements shown in Figure 6 7 can be used to build a total phasing arrangement for the whole intersection a complete signal cycle The simplest signal phasing at an intersection involves two through phases with filter right turns and parallel pedestrian movements as illustrated in Figure 6 2 By allocating right of way to each road alternately the two phase system eliminates all crossing conflicts between through traffic movements However it leaves four turning conflicts between right turn and through vehicles four merge conflicts between right turn and left turn vehicles and eight turning vehicle pedestrian conflicts as shown in Figure 6 3 Some of these turning conflicts
285. rea a A single broken outline will permit vehicles to cross the median or island to overtake vehicles enter an abutting property or enter the road from an abutting property 74 b A single unbroken outline will prevent overtaking but enable a vehicle to cross the median or island to enter a turn bay enter an abutting property or enter the road from an abutting property Double unbroken outlines will prevent overtaking turning to access an abutting property entering the road from an abutting property or crossing the painted area to enter a turn bay c Traffic signal posts must not be placed in the painted areas and should always be located behind raised kerbing 10 5 Pavement Messages and Symbols The use of pavement messages and symbols should be minimised in advance of signalised intersections They may be hazardous if placed in the path of braking traffic Where advance warning of signals is required signs should be used in lieu of pavement messages see Section 11 3 11 The KEEP CLEAR marking may be used at minor un signalised intersections and access roads where entering or exiting traffic may be impeded by queues from a nearby signalised intersection Pavement arrows in a lane are provided to indicate the direction in which a driver is legally obliged to travel through the intersection from that lane They should only be used where necessary so that skidding prob lems for motorcycles are minim
286. reasons a reduction in safety due to the higher number of conflict points the larger intersection conflict area and the difficulty for right turning motorist to select appropriately sized gaps in opposing traffic on two carriageways during the given signal phase and b reduction in intersection capacity because of increased pedestrian and vehicle clearance times Thus where service roads are provided problems can be minimised by terminating the service road or by carrying it around the corner as a left turn movement only AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 4 Signal System and Components 4 1 System 4 1 1 Purpose Signal control is provided to a reduce traffic conflicts and delays b share time between conflicting movements c reduce crashes 4 1 2 System Process As seen in Figure 4 1 which illustrates the signal system process demands for traffic movements are identified through vehicle detectors pedestrian push buttons and where relevant externally supplied data from a master control computer The signal system transforms traffic demands in a manner determined by the cont roller algorithms and operational settings into a sequence of signal displays Also see Figure 1 1 in Section 1 for the interaction between a traffic signal system and various external factors 4 2 Components The major components of the signal system are listed in Table 4 7 together with the purpose o
287. reen ii Red and Yellow arrows Red to Off to Yellow to Red iii Red and Yellow arrows Red to Flashing Yellow to Off to Red iv Red and Yellow arrows Red to Flashing Yellow to Yellow to Red d Any green display shall always be followed by a yellow display applicable to that movement although not necessarily in the same column of duration sufficient for termination of that movement e A red display must be preceded by its associated yellow display where present or a circular yellow display The alternatives for use of the Flashing Yellow enables termination of the phase by either a yellow disc or a yellow arrow as considered appropriate for the application Figure 5 19 gives examples of fully controlled right turn display sequences for six aspect arrangements As a general principle only one colour change is desirable at a time and a red or green display change during a yellow circle or yellow arrow display is not desirable except with diamond overlap phasing where these conditions can occur due to the independent operation of circle and arrow displays 29 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 5 7 3 Right Turn Sequences In addition to the examples of right turn display sequences for six aspect arrangements shown in Figure 5 19 examples of display sequences to initiate and terminate arrow controlled right turn movements are illustrated in Figures 5 20 and 5 27 respectively
288. reen and Early cut off yellow upstream and downstream movements refer to an example of paired intersection Start of Phase Running intervals Phase change End of point Phase Clearance intervals Intergreen Green Downstream movement Upstream movement C 4 6 Vehicle Clearance Settings Intergreen period as a vehicle change and clearance interval involves two intervals a a yellow interval to warn approaching drivers that the phase is terminating and b an all red interval to enable vehicles within the intersection to clear the controlled area There is a large number of publications on determining appropriate values of Yellow Time and All Red Time e g Hulscher 1980 1984 ITE 1994 It is recom mended that the Yellow Time be set as detailed in Section C 4 6 7 and the All Red Time be set as detailed in C 4 6 2 C 4 6 1 Yellow Time The purpose of the yellow interval is to provide sufficient warning of the termination of the phase A driver must stop for a yellow display provided it can be done safely Table C 2 indicates that typical Yellow Times used in practice are in the range 3 0 to 6 0 seconds 130 Traffic regulations prohibit the entry of vehicles into a controlled area when a red signal is displayed The yellow signal is used to allow for the fact that a traffic stream cannot be stopped abruptly at the end of the green interval The stopping performance of
289. rk capacity caused by incidents and other factors such as road works Fully adaptive control systems require expertise to set up and review if optimal performance is to be main tained The flexibility of the system is dependent on a large number of detectors The cost of installing and maintaining these detectors is high compared to lower performing fixed time systems 13 6 Design Factors While detailed aspects of the design process are quite specific to the control system chosen the following factors are taken into account in designing signal coordination systems a Traffic Management Policies The strategies for the routes and networks to be coordinated should be determined including public transport considerations see Sections 13 1 and 15 5 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 b Roadway Factors Information is required on the capacities of roads both at and between intersections This enables an assessment of the manner in which traffic platoons will behave The effective capacity of the coordinated system is determined by the capacities of critical intersections that must be identified In addition data on the geometry of the intersections in the network including the location of existing and planned intersections and signalised crossings and the distances between the stop lines are required c Geometric Factors Examination of intersection and roadway geometry may indicate the need
290. rom the intersection and relocation of the stop line would require a longer intergreen period flashing or non flashing signals may be used Section 15 4 2 These are operated from the emergency service facility to allow safe exit of the emergency service vehicles A special emergency service phase may be provided at the intersection if it is warranted on the basis of i conflict between emergency service vehicles and other traffic ii possibility of queued vehicles blocking the exit from the emergency service facility or iii delays to emergency service vehicles if the emergency service phase is not provided The special emergency service phase should clear any queued vehicles within the path of the emergency vehicle to allow it unimpeded travel in any direction through the intersection Figure 15 2 Signals for midblock access points to or from emergency service facilities a Typical signal location Emergency vehicle entry b Signal face flashing signals AUSTROADS 97 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 15 4 2 Signals for Midblock Access Points Signals for midblock access points from emergency service facilities shall comprise signal faces provided in accordance with Figure 15 2 a in one of the following forms a Non flashing signals If provided as a two aspect signal face the display sequence shall be Off to Yellow to Red to Off If provide
291. rrently in use a Loops Trams in a dedicated lane may be detected by inductive loops placed between the rails They may produce passage or presence actuations b TZ Transponder Transmitter Systems In a mixed traffic lane inductive loops do not uniquely identify trams Transponder or transmitter systems as described in Section 8 5 7 for buses can be used c Skates Skates are overhead contacts in the energy supply lines to the tram As the tram pickup passes a momentary isolated contact closure is transmitted to the controller These perform a locked call function only 8 5 3 Bicycles When separate bicycle lanes are provided and bicycle detection is required loop detectors with very sensitive loop arrangements spanning the whole width of the bicycle lane are necessary An evaluation of inductive loops for bicycle detection has been reported by Leschinski 1994 67 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Where bicycle traffic shares lanes with other vehicles it is not possible to ensure detection of bicycles due to their narrow width In this case push buttons may be provided in special positions to assist bicycle riders to lodge a demand Figure 8 6 Push button location and orientation 1 Arrow legends point upwards on these push buttons 2 Arrow legends point horizontally on these push buttons 8 5 4 Emergency Vehicles Emergency vehicles can be selectively det
292. rsection mA R Secondary nad an lem secondary Primary f Dual primary Overhead primary Approach b Divided road approach at a cross road intersection ertiary Secondary Dual far right secondary Overhead tertiary Soora secondary Dual primary Primary Overhead primary Approach 50 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 LOCATION OF SIGNAL EQUIPTMENT Figure 7 2 Signal face designations for T intersections and midblock signalised crossings a Terminating road at a T intersection Tertiary Secondary 7 Alternative position if no median or median is too Primary Dual primary Dual primary pes Overhead primary Approach b Midblock signalised crossing Primary gt Approach Tertiary Pedestrian Secondary 7 3 Signal Face Functions A design must provide for the following signal face functions for each approach as relevant a Warning Display To alert the approaching drivers to the presence of traffic signal control b Stopping Display To inform approaching drivers sufficiently in advance of the stop line that they are required to stop AUSTROADS c Starting Display To inform drivers stopped at the stop line when they may proceed d Manoeuvring Display To inform drivers about to enter the intersection or within the intersection of any priority or restriction allocated to them Each signal
293. s All signals in centrally controlled systems are connected to the traffic control computers usually by leased data lines or in some cases by dedicated cable systems In Australia and New Zealand SCATS Sims 1979 Sims and Dobinson 1979 Lowrie 1982 1990 1996 2001 Charles 2001 is widely deployed except in Queensland where the STREAMS and BLISS systems are in use The SCATS system is also used in many cities around the world Typical system architecture used in the PC based SCATS 6 system is shown in Figure 13 2 For detailed description of the SCATS system refer to Lowrie 1996 Figure 13 2 SCATS 6 PC based wide area control system architecture LAN WAN Local controllers up to 250 local controllers per region Regional computers up to 64 regions Cm Cm EPS Control Central ITS Central Remote room management services workstations workstations functions AUSTROADS 87 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 13 5 Coordination Methods Traffic control systems to implement signal coordination can be categorised as follows according to the operating method control philosophy employed i fixed time plan selection system ii traffic responsive plan selection system and iii fully adaptive system These are discussed in Sections 13 5 1 to 13 5 3 13 5 1 Fixed Time Plan Selection System In fixed time control systems predetermined signal timing plans ar
294. s Close to a Signalised Intersection 15 4 2 Signals for Midblock Access Points Public Transport Priority 15 5 1 BUS POLY ee doa o dox n taa 15 5 2 TramPriority 15 5 3 Operation cem Bicycle Facilities Roundabout Metering Signals Ramp Metering Signals Special Intersection Treatments 15 9 1 Seagull T Intersections 15 9 2 Paired Intersections 15 9 3 Intersections With More Than Four Legs Overhead Lane Control Signals Single Lane Operation and Portable Signals 15 11 1 Single Lane Operation 15 112 Portable Signals Left Turn On Red Metering Signals at Sign Controlled Intersections TT 91 Ree Co 91 ich avaeath oh Rua Peaks 91 91 M MEET 92 etwas 92 je tea he d Rd eR ate dre ta ils 92 E ae taie 92 M 92 T de ene een 93 DTP 93 93 TITO 93 E 93 M 94 O 94 Bg ann ou as aera Wha RR MEE 94 TD 95 ET TT ET 95 Se ang agar 95 TET 96 JT 96 ra 96 beside sh dt set qe de ed 96 ne ee eee eee 97 97 Xd d dea kd ah E o 97 E cd EN 98 T 98 de
295. s Off to Green to Yellow to Off A regulatory sign STOP HERE ON RED SIGNAL Section 11 3 2 is used at the major road stop line as in the case of roundabout metering signals AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 Appendix A Human Factors A 1 General This appendix discusses aspects of human character istics relevant to traffic signal control Road users including drivers pedestrians and cyclists are engaged in a variety of tasks in the road environment and have unique elements and characteristics in relation to traffic control purposes Knowledge of human capabilities and behavioural characteristics is a vital input to the successful development of all aspects of traffic engineering and control Ogden 1996 Similarly some critical characteristics of vehicles using road facilities need to be considered in the design of road and traffic control elements Gardner 1996 Vehicular traffic factors are discussed in Appendix B Detailed treatment of pedestrian and bicycle traffic characteristics can be found in the Highway Capacity Manual Chapters 11 18 and 19 TRB 2000 ITE 1998 and Austroads GTEP Part 13 Pedestrians and Part 14 Bicycles Transit bus tram light rail concepts and analysis methods can be found in the Highway Capacity Manual Chapters 14 and 27 TRB 2000 Detailed information on human and vehicle factors can also be found in Lay 1985 A simplified block diagram that shows the basic ele
296. s recorded or to prevent a demand being recorded unnecessarily Typical values of the Presence Setting used in practice are in the range O to 5 seconds Examples of the use of this setting are a shared lane detector for lagging right turn phasing 2 to 5 seconds b left turn detector on overlapped movement 3 seconds c left turn on red lane detector zero Figure C 5 All Red Time as a function of speed vp and clearance distance L 40 4 Lc 40m S 304 KR S T Re ml 3 Le 20m M n C ERR lt 10 Lc215m ma M9 0 0 i 40 50 70 80 Design speed vp km h 132 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 C 4 7 2 Headway and Waste Settings The purpose of Headway Space Time Setting is to set the desirable space time between successive detector actuations for efficient traffic flow It is used in assoc iation with the Waste Setting In general traffic engineering usage the term head way means the time between passage of the front ends of two successive vehicles at an observation point e g at the leading edge of the detector As such the term Headway Setting is a misnomer as it is a space time value see Appendix B 3 2 As seen in Table C 2 typical Headway Settings used in practice are 0 3 to 1 5 seconds for through move ments and 0 6 to 1 2 seconds for arrow controlled right turn movements The Headway setting can be rela
297. se see Section 6 3 3 Had the right turn volume from South approach been considerably higher a diamond overlap phase design would have been assessed see Section 6 3 5 This would have required an exclusive right turn lane to be provided on the South approach as well The left turn movement from North slip lane gives way to right turns from South in Phase A and to through traffic from West in Phase B This movement is designated as undetected and therefore will not affect signal timings The right turn movement from North receives two distinct green periods namely unopposed during Phase C and opposed during Phase A stopping during the intergreen time between Phases C and A On the other hand the through movement from North has a single green period although it runs during both Phases C and A it is not stopped during the intergreen time between Phases C and A The intergreen time for Phase C is calculated on the basis of the conflict between the right turn movement from North clearing the intersection and the pedestrian movement in front of the West approach starting Negotiation radius for this movement is measured as 15 m and the negotiation speed and distance are calcu lated as 22 km h and 24 m Using t 1 5 s ay 3 0 m s Vp 22 km h and G 0 07 in Equation C 4 2 yellow time is calculated as t 4 1 s Using Lo 2 24 m in Equation C 4 3 all red time for 60 km h zone is found as t 1 7 s Therefore inter
298. section would be operating at practical capacity after 8 years Based on the above analysis results it may be concluded that Design 2 provides a satisfactory solution to the problems experienced with Design 1 Figure D 10 Average delay vs cycle time for Design 2 with reduced maximum green settings 30 28 4 26 4 24 4 22 4 Average delay s 20 4 18 16 14 r 60 70 80 90 100 110 120 130 Cy cle time s AUSTROADS 145 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Figure D 11 Lane flow capacity and performance results for Design 2 for a selected cycle time of 90 s Austroads Guide TEP Part 7 Traffic Signals Worked Example TEP7D2 Design 2 Three Phase Option Intersection ID TEP7B Actuated Coordinated Signals Cycle Time 90 Table S 7 Lane Performance Effective Red Arv Flow Cap Aver Eff Queue Shrt Lane amp Green Times sec veh veh Deg Delay Stop 9596 Back Lane No R1 G1 R2 G2 h h Satn x sec Rate vehs m m South Main Road South 1 LT 63 27 0 0 417 548 0 760 33 9 0 80 18 3 135 PEN 60 30 0 0 467 614 0 760 29 1 0 77 19 5 144 3 TR 61 29 0 0 257 339 0 760 33 4 0 79 11 9 86 East Side Street East 1 LT 60 30 0 0 176 307 0 575 29 0 0 70 74 59 50 2 TR 70 20 0 0 188 326 0 575 38 8 0 78 9 1 66 North Main Road North 1L 6 48 16 20 85 943 0 090 10 5 0 67 0 9 7 70 2T 42 48 0 443 987 0 449 3 4 0 17 4 5 33 20 42 48 0 439 976 0 4
299. sed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 3 6 Kerbside Allocations 3 6 1 Parking Appropriate management of parking on approach and exit roads is needed for efficient intersection operation Results of inappropriate management are a a reduction in the number of effective approach lanes b TZ a reduction in the number of effective departure lanes c d misleading detector actuations obstruction of signal displays and other control devices e reduced sight distances for vehicle or pedestrian traffic and f decreased capacity and increased delays and queue lengths Where statutory restrictions are not adequate parking prohibitions and restrictions are necessary to reduce these difficulties Analysis of how additional parking restrictions and prohibitions can improve the inter section performance can be performed using computer programs for intersection analysis 12 3 6 2 Bus Zones The effect of bus bays or zones close to the intersection is similar to that of short term parking Bus stops on the approach to intersections cause detection difficulties when designing bus priority schemes Bus stops on the departure side of the intersection can cause following vehicles to queue into the intersection unless a fully indented bus bay is provided 3 7 Service Roads Generally service roads should not be carried through signalised intersections for the following
300. see Appendix B 3 2 For example where the Gap Setting is 3 0 seconds and the detector occupancy time at a given speed is 0 7 seconds and the headway equivalent of this setting is 3 7 seconds The gap timing logic operates from the start of the green period to enable a green termination at the end of the minimum green period or the rest interval It operates for the whole of the running part of the phase including the rest interval The gap timer is loaded with the Gap Setting when a detector actuation occurs With presence detection the gap timer starts decrementing from the initial value of the Gap Setting when detector actuation ceases If the gap timer reaches zero before the next detector actuation the timer is said to have timed out or gapped out When this occurs during the extension green interval the green period is terminated subject to parallel pedestrian movement timing constraints This point during the phase is called the phase change time This type of extension green termination will be called a gap change The phase change process starts with the yellow signal display unless there is an early cut off green interval in which case the early cut off yellow interval starts Section C 4 5 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 The current Australian control method employs Headway and Waste Settings as additional extension settings The headway waste control method aims to terminate the extension
301. selection of the duration of design period 60 minute 30 minute or 15 minute peak for the purpose of capacity and performance analysis See Austroads GTEP Part 3 Traffic Studies and Section 8 of ARR 123 Ak elik 1981 Motor Vehicles Traffic volumes for the relevant peak periods are expressed in hourly flow rates These should also include information about traffic composition in terms of turning movements and heavy vehicles For definitions of different vehicle classes see Section 5 5 of ARR 123 Ak elik 1981 and Section 9 of Austroads GTEP Part 2 Roadway Capacity These data are normally obtained from manual counts of at least two hour duration for each peak period Usually 15 minute summation intervals are used so the peak flow rates can be identified Traffic counts may vary by day of the week or because of weather school or public holidays or other abnormal conditions The designer should consider the circumstances of the count and adjust or recount if necessary before determining the volumes for the design Pedestrians and Bicycles Counts should identify the pedestrian volumes crossing each vehicle approach and the proportion of children aged or other pedestrians with special needs included in these volumes These are required to enable specific features to be designed where necessary Bicycle volumes should also be counted both along and across each vehicle approach to identify the need for special features in
302. sented at different aggregation levels i e per movement vehicle and pedestrian per lane per lane group or approach and for the intersection as a whole Average total or maximum values are used as applicable e g average delay total operating cost and maximum degree of saturation Detailed information about output statistics and ana lytical models used for predicting them can be found in the aaSIDRA User Guide Ak elik amp Associates 2001a Output data requirements include the following a Input Data Listing and Processed Input Data The listing of input data helps the analyst to check the input data including the default values used Processed data includes arrival demand flow rates that are determined by adjustments to user specified volumes to take account of the volume counting period peak flow factors and flow scales 137 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Figure D 1 Current intersection layout Design 1 E 24 5 d l FT 7 down i dg se D O 4 513 413 213 4 Shopping No Stopping Zone 4 p centre 50m T 32 L Signalised 3 up crossings Side 12 8 Street Des 32 Level Cp 3 2 ELP Parking E j 50m No Stopping Zone Shops b Signal Timings i Cycle time displayed green times for phases and effective green times for movements For actuate
303. should be used where needed by visually impaired or elderly pedestrians Hulscher 1976 Additional detectors in the footpath or overhead usually infrared or microwave may be used to detect the presence of pedestrians on the crossing and to modify the duration of the Walk or Clearance Flashing Don t Walk intervals e g Puffin crossings 8 4 2 Automatic Introduction of Pedestrian Movements In addition to push button detection controllers may also be set to register a fixed demand for any pedestrian movement so that the movement runs each cycle This should only be considered where the pedestrian volumes are high and the cycle time is long enough to accommodate all phases with pedestrian movements Automatic introduction may be invoked by time of day or on the condition that the coordinated signal cycle time exceeds a certain value 8 4 3 Push Button Location a General Pedestrian push buttons are normally mounted on traffic signal posts or mast arms The push buttons shall be located at each end of the signalised crossing and at each pedestrian refuge Consideration should be given to provision of a push button on any median island signal post Typical locations of push buttons are illustrated in Figure 8 6 They should be located so as to be clearly visible to approaching pedestrians and should not be obstructed by other road or footpath furniture b Height The push button should be mounted at a height of 1m
304. signal controllers linked with railway level crossing controls are given in a VicRoads 1997b document titled Linking Traffic Signals to Railway Level Crossings 15 3 2 Linking Requirements If linking with the railway level crossing is justified track switches should be provided by the railway authority to enable the special queue clearing sequence to be initiated before the flashing red signals commence to operate The road signal sequence should be arranged so that after the queue clearing phase has terminated no phases or turning movements can be introduced for traffic needing to cross the rail tracks until the train has cleared The railway track switches should provide an indication when the train has cleared the level crossing In the case of a rail crossing provided with manually operated gates no special provision is generally required When the level crossing opens to road traffic the normal phase sequence is restored and some compensation can be given to the waiting traffic Provision of additional storage may be necessary for vehicles that cannot be released while the railway crossing is closed Common inputs from the railway level crossing control system are given in Section 8 5 6 15 3 3 Railway Road Crossings within the Intersection It may be possible to include the railway road crossing within the conflict area In this situation the train movement will need to be treated as a priority phase The flashing
305. signalised intersection design The design process is the orderly combination of these tasks into a rational and effective design sequence as shown in Table 1 1 Appendices A and B provide the theoretical back ground material for users of this guide Appendix C discusses general aspects of signal timing methods describes actuated signal controller operation and presents guidelines for determining appropriate values of controller settings Appendix D illustrates some aspects of the design process for a sample intersection 1 8 Construction Construction methods employed depend on local resources and practices and are not addressed in this guide It is important to maintain safe traffic operations during signal installation and reconstruction Thus suitable staging of works should be considered The control arrangements at the intersection where the signals are being installed or at adjacent intersections may require special attention during the construction period 1 9 Operation Signal installations should be checked periodically to ensure that the signal operation accommodates any changes in traffic or environment that may have occurred e g increased or decreased demand volumes In general feedback from road users may be sufficient to ensure that the phasing and signal timings are appropriate Feedback from electrical maintenance staff and other traffic professionals should be encouraged to ensure that the signals continu
306. signs Regulate inform and guide traffic AS 1742 11 Roadway Serve normal road engineering Austroads components purposes Guides and ocal Finial cap Prevent inadvertent contact with live AS 2339 12 terminals and to protect the terminal assembly and associated wiring from the weather Arrow and Permit the display of special arrow AS 2144 5 A other masks symbols that control specific turn movements Local traffic administration specifications Figure 4 2 Traffic signal components Outreach Overhead lantern Overhang Target Junction Lantern board I Finial box mounting inial cap strap lt Upper mounting bracket Split shell mounting bracket Three aspect lantern Visors Pedestrian lantern f lt Pedestrian push button Clearance 5 4 m minimum Accessed by AR M VICROADS on 02 Jun 2005 Traffic signal post Traffic signal mast arm Joint use traffic signal and street pole Combination traffic signal mast arm and street light 16 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 4 2 2 Associated Equipment Equipment associated with the lanterns include AS 2144 Lamps Lamps of special manufacture are required for signal lanterns They are designed to be compatible with the optical system of the lantern to produce the specified light output and to obtain the best possible life charact eristics to minimise lamp replacement see Section 14
307. sses the minor road for each of two one hour periods of an average day the pedestrian flow exceeds 60 ped h OR A midblock signalised crossing is warranted within 130 m OR c d Where the pedestrian flow criterion is not met but one or more of the following conditions apply i A number of young children will use the crossing OR Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS ii Elderly or handicapped pedestrians will use the crossing OR iii There will be a hazard to pedestrians due to the width of the carriageway greater than six lanes or 25 m OR iv There will be a hazard to pedestrians due to the high speed or number of vehicles 1 6 Environment This guide is applicable to most Australian environments Engineering judgement should be exercised to confirm its relevance where local conditions occur which may obstruct a driver s vision snow fog pollution affect a vehicle s performance ice sand steep grades or affect the interaction between drivers vehicles pedestrians and traffic signals Figure 1 1 illustrates the interaction between the signal system and various external factors including a road user requirements b TZ expectations of travel conditions c public transport policies d vehicle and pedestrian movements and e accident rates 1 7 Design Process Subsequent chapters of this guide examine the indi vidual tasks of
308. ssible facilities are a time of day linking synchronous or cableless linking b linking by dedicated cable c serial communication telephone cable radio These facilities are discussed in detail in Section 13 9 3 2 Controller Capacity The controller capacity required is determined by the number of signal groups which must be switched and the number of detector and push button input circuits These requirements can be determined from the inter section geometry and the phasing design Spare cap acity may be required for future expansion of the intersection phasing 9 3 3 Controller Operation and Maintenance When selecting a traffic signal controller consideration should be given to the operation and maintenance requirements of each type The staff required for these purposes must be familiar with controller type For new controller types or controllers installed in remote areas consideration needs to be given to the ability of staff to operate and maintain the controllers Arrangements may need to be made for training operations support and spare parts for maintenance 9 4 Controller Programming The task of configuring a controller to the specific requirements of a particular site is known as adaptive engineering Each controller has a unique program called a personality which configures the controller to the specific operational design of the intersection or midblock device it is controlling Traffic signa
309. system has been used for tram detection in the Melbourne tram priority system The system allows a positive coupling between the transponder and in ground detector loops to selectively detect trams in a mixed traffic stream Bus Only Lanes are used as an effective measure of public transport priority A white B signal aspect display permits a bus to move in any direction from the stop line of a bus only lane The movement must be made with safety and in accordance with any regulatory requirements Detailed information on the use of bus lanterns at signalised intersections can be found in RTA NSW 1998 A Queue Relocation method has also been used for bus priority This method limits the queue length at the downstream intersection The bus priority system at the upstream intersection allows buses to advance AUSTROADS SPECIAL APPLICATIONS AND FACILITIES to the end of the queue at the downstream intersection before other traffic leave the upstream intersection The buses are then in position to take advantage of the green period at the downstream location 15 6 Bicycle Facilities Detailed information on bicycle facilities in general can be found in Austroads 1999 GTEP Part 14 Bicycles AS 1742 Part 9 and in Veith 1996 Usually bicycle facilities are combined with pedestrian facilities at signalised intersections and midblock signal ised crossings Signal aspects and sequences for bicycle and pedestrian signals are described
310. t and sight distance available to allow safe filtering of right turn movements c traffic flows the amount of traffic including proportion of heavy vehicles in each through or turning movement d TZ signal coordination progression considerations for an intersection within a coordinated signal system e pedestrians which pedestrian movements need to be controlled and how they will be catered for in the phasing system and f special vehicles whether or not buses trams bicycles need to be separately controlled and how they will be catered for in the phasing system The design of a phasing system cannot be separated from the design of lane arrangements The allocation of lanes to various movements from each approach road must therefore be considered carefully in designing phasing systems Phasing design should also consider safety implications of intersection signal operation during low demand periods when normal phase sequencing may not occur due to phase skipping Certain timing constraints are imposed on signal operation for reasons of safety and maximum tolerable delay Signal controller settings subject to constraints for safety reasons include minimum green time mini mum pedestrian walk time minimum red arrow display time pedestrian clearance time and intergreen time This subject is discussed in detail in Appendix C AUSTROADS SIGNAL PHASING 6 2 2 Evaluation of Phasing Design Alternative sign
311. t crossing is used as the clearance distance The pedestrian walking speed for determining total clearance time is usually 1 2 m s A clearance speed of Ve 1 0 m s may be appropriate for sites with higher populations of slower pedestrians Figure C 6 shows the distribution of walking speeds at mid block signalised crossings in Melbourne Ak elik amp Associates 2001b This indicates that the recommended clearance speeds of 1 0 and 1 2 m s correspond to 5th and 15th percentile speeds respectively i e approx imately 5 per cent of pedestrians were observed to cross with speeds below 1 0 m s and 15 per cent of pedes trians were observed to cross with speeds below 1 2 m s C 5 3 Pedestrian Delay Setting The Pedestrian Delay Setting is used to provide a delay between the push button actuation and the placement of the pedestrian demand see Figure C 2 This helps to form pedestrian platoons and thus avoid unnecessary introduction of the pedestrian movements Where used typical Pedestrian Delay Setting is 5 to 10 seconds applicable to both midblock pedestrian controllers and intersection controller with completely independent pedestrian feature AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 APPENDIX C SIGNAL TIMINGS Figure C 6 Walking speeds of pedestrians observed at three mid block signalised crossings in Melbourne 100 d a 20 N o 804 bo 70 4 o 60 a bp 504 amp 2 404
312. t mounted in the controller cabinet or on a signal post Presence or movement of a vehicle as a large mass of metal over a loop reduces the loop inductance and causes a detector output This output is the closure of a relay contact or the equivalent operation of a semiconductor 17 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Alternative forms of detection such as microwave infrared or video may be used where appropriate Pedestrian demands are usually recorded when a pedestrian presses a push button AS 2353 mounted on the side of the signal post see Section 8 for details Other pedestrian sensors such as overhead infrared or microwave sensors and pressure pads in the footpath may also be used Detection of bicycles and light motorcycles is more difficult but may be achieved by attention to the design of the loop see Section 8 3 Priority vehicles may also be detected if special detector systems are used 18 4 2 7 Roadway Components These include islands medians pavement markings and signs AS 1742 Such components are not unique to traffic signal installations but they are an integral part of the installation and affect its design and performance 4 3 Component Selection The selection of the components to be used for a signal installation will be determined by the signal design Consideration should also be given to factors such as availability of components maintenance requirements stock
313. t to conflicting green signal groups and close the circuit to the red of these signal groups One method of interlocking signal groups is effected by connecting relay contacts in series to create a chain from the lamp active supply to the green feeds of the signal groups When a signal group is switched to green the green feed to signal groups lower down the chain is open circuited green interlocking The groups which are higher in the chain must ensure the red is displayed for groups which are lower in the chain red interlock Signal groups which are designed to have an Off display should be in the lowest positions in the chain They do not require a red interlock as this would override the off display Conflict monitoring is mandatory where solid state lamp switching is used The circuits to the signal group colours should be monitored as closely as possible to the controller output terminals The state of each circuit is compared with a table of conflicting signal groups specified in the personality so that unsafe displays are avoided A detailed study of the techniques used is beyond the scope of this guide Figure 9 2 indicates the acceptable undesirable and unsafe lantern displays The adaptive engineering required is equipment dependent 71 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Figure 9 2 Safety of signal displays Green amp Red Green amp Yellow Green amp Yellow amp Red Walk amp D
314. tation Engineers Prepared by the ITE Technical Council Task Force 4TF 1 Washington D C U S A AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 ITE 1997 Preemption of Traffic Signals at or near Railroad Grade Crossings with Active Warning Devices A Recommended Practice of the Institute of Transportation Engineers Prepared by the ITE Traffic Engineering Council Committee TENC 4M 35 Washington D C U S A ITE 1998 Design and Safety of Pedestrian Facilities A Recommended Practice of the Institute of Transportation Engineers Prepared by Traffic Engineering Council Committee TENC 5A 5 Washington D C U S A ITE Australian Section 1985 Management and Operation of Traffic Signals in Melbourne Australia Prepared by the ITE Australian Section Committee on Traffic Signals Melbourne Australia JARVIS J R 1982 In service vehicle performance In Traffic Energy and Emissions Joint Society of Automotive Engineers Australasia and ARRB 2nd Conference Melbourne Australia LAY M G 1985 Source Book for Australian Roads 3rd Edition ARRB Transport Research Ltd Vermont South Australia LESCHINSKI R E 1994 Evaluation of inductive loops for bicycle detection Proc ARRB Transport Research 17th Conf 17 5 pp 119 131 ARRB Transport Research Ltd Vermont South Australia LI M 1988 Modeling oversaturated conditions in TRANSYT 7F Release 8 McTrans Newsletter Volume 13 Summer 1998 Tra
315. te signal display 11 3 13 Fault Reporting Sign The fault reporting sign is used to inform pedestrians and motorists of the reporting procedure for signal faults Figure 11 13 The use of this sign is recom mended to encourage the public to report faults The sign or signs should be mounted on the signal controller to be visible to passing traffic It should show the follow ing information in black letters at least 15 mm high 80 a identification of the maintenance authority b a 24 hour telephone number to report faults and c an identification code number for the installation if required 11 3 14 Other Signs Other signs used at signalised intersections include FORM 1 LANE G9 15 FORM 2 LANES G9 16 NO HOOK TURN BY BICYCLES R2 22 and Symbolic Walking Legs sign for pedestrian Zebra crossings on slip lanes R3 1 Figure 11 12 NOT IN USE temporary sign NOT IN USE Figure 11 13 Example of fault reporting sign 40 RTA TO REPORT FAULTY SIGNAL OPERATION PLEASE PHONE 9211 3000 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 12 Electrical Design 12 1 General Electrical design is required for power and lighting cir cuits for the interconnection of signal components including controllers lanterns detectors and push buttons Cabling and wiring involved may provide one or more of the following a 240V 50 Hz circuits for lamps and post mounted detectors
316. ted to the SCATS parameter Space Time at Maximum Flow The values of this parameter were found to be 0 85 to 1 02 seconds for through move ments and around 0 61 to 0 74 seconds for arrow controlled right turn movements Ak elik Besley and Roper 1999 The waste is the sum of the excess of the actual space time over the Headway Setting The Waste Setting is used to set the value of this sum at which the phase is terminated Section C 3 1 However research has indicated that with efficient Gap Settings as discussed in Section C 4 4 the phase or signal group is more likely to gap out before a phase change due to the Waste Setting Where employed the Waste Setting may be determined as 10 20 per cent of maximum green time minimum green time plus Maximum Extension Green Setting subject to a minimum value of 4 seconds and a maxi mum value of about 12 seconds Table C 2 indicates that typical Waste Settings used in practice are 4 to 11 seconds for through movements and 2 to 8 seconds for arrow controlled right turn movements C 4 7 3 Minimum Red Arrow Time The minimum duration of a red arrow signal display is governed principally by driver reaction perception characteristics It is recommended that as a safety constraint a minimum value of 3 seconds be used AUSTROADS APPENDIX C SIGNAL TIMINGS C 5 Pedestrian Settings Actuated controller settings for pedestrian movements are described in the following sections se
317. tenance records also provide a basis for the review of specifications and guidance in the appraisal of equip ment tendered for purchase A good maintenance record should include the following data a Fault advice i date and time ii source iii location and iv apparent nature b Service report i date and time of arrival and departure ii location iii travel involved iv personnel identification v action taken to clear fault vi details of further work required and vii materials used including description and serial numbers of operational spares installed and removed c Shop service records i date and time returned for service service actually started service completed ii description and serial numbers of units iii repair hours involved and iv materials used in repair AUSTROADS INSTALLATION CHECKS AND MAINTENANCE 14 3 3 Preventative Maintenance Preventative maintenance involves the provision of service before failure occurs Periodic maintenance is scheduled so that equipment operates between routine servicing with an estimated probability of breakdown These techniques reliability engineering and preven tative maintenance scheduling are beyond the scope of this guide 14 3 4 Breakdown Maintenance Despite efforts to maximise equipment availability random breakdowns will occur and must be repaired Notification of failures can be expected from Police other agen
318. tenus 13 17 Mie 17 SERES 17 Tr 17 PE 17 18 i ives 18 adus 19 TETEN 19 nie 19 addis 19 ie ans 19 19 eos 19 TEREE 19 des 20 PE 21 Den 21 21 bat 22 22 TE 23 are 23 D 23 TET 23 24 24 Lun 24 usa 25 TOE 25 ae 26 ae 29 su dans 29 29 TENET 30 S 30 shine 34 PE 34 34 hol 34 Rida 34 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 CONTENTS 5 9 Bicycle Signals zac ect rosier Tamer LAN CR Cac etu 5 9 1 Signal Face Layout osea ete Bate Der ete ROCA AT E dk 5 9 2 Basic Sequence iip rer PA PW RA da PATE POE ORES EP ERA 5 9 3 Procedure without Bicycle Displays 5 10 Special Vehicle Signals 5 10 1 Signal Face Layout 5 10 2 Special Vehicle Sequence 5 11 Signal Start Up and Failure Displays 5 11 1 Signal Display on Failure 5 11 2 Signal Display on Start Up 6 Sigal PHASING 2120 ie en ne ERE EET ne do eddy deiode 6 1 Introduction and Scope 6 2 General Requirements for Signal Phasing 6 2 1 Fundamental Rules 1 424444 44 AGA esi c9 inde ee ee 6 2 2 Evaluation of Phasing Design
319. teria are not met OR AUSTROADS INTRODUCTION iii The flow warrant for a pedestrian Zebra crossing is realised see AS 1742 Part 10 and Austroads GTEP Part 13 Appendix B but its provision could cause a hazard to pedestrians because of the width of the carriageway insufficient sight distance to the crossing or the speed or number of vehicles OR iv The site meets the warrants for a pedestrian Zebra crossing but a signalised crossing would improve traffic flow by enabling it to be coordinated with another site or sites In accordance with AS 1742 Part 10 and where regu lations permit Pelican crossings Section 6 5 3 may be provided if a a pedestrian actuated mid block signalised crossing is justified using the above guidelines b the site would benefit from reduced vehicle delays and c the site is an area where the 85th percentile speeds are 80 km h or less 1 5 3 Warrants for Pedestrian Signals at Signalised Intersections The following guidelines for pedestrian signals at signalised intersections differ from those given in Austroads GTEP Part 13 Pedestrians and AS 1742 Part 10 As a guide pedestrian signals may be considered at a signalised intersection if one of the following warrants is met a Where the pedestrian movement crosses the major road for each of two one hour periods of an average day the pedestrian flow exceeds 30 ped h OR b TZ Where the pedestrian movement cro
320. terminated by a minimum change or a maxi mum change The minimum change occurs when the phase ends at the end of the minimum green period when a demand for another phase has been received and the gap timer has timed out before the end of the minimum green period AUSTROADS APPENDIX C SIGNAL TIMINGS The maximum change occurs when a gap change or waste change has not occurred during the extension green interval and the total green extension time equals the maximum extension green setting In summary subject to demand for another phase the green period can be terminated by one of four methods i a minimum change ii a gap change iii a waste change or iv a maximum change C 3 2 Pedestrian Intervals At a signalised intersection pedestrian movements can run concurrently with parallel vehicle movements or run in an exclusive pedestrian phase At midblock signalised crossings vehicle and pedestrian movements run in alternate phases see Section 6 5 3 Normally pedestrian movements phases are intro duced by push button detection For parallel crossings at intersections pedestrian demand needs to be received before the relevant phase starts Pedestrian movements phases can also be introduced automatically in areas where heavy pedestrian movements exist The pedestrian movement phase intervals as well as their relationship with parallel vehicle movement intervals applicable in the case of parallel vehicl
321. tersection is prepared next according to the general requirements indicated in Section 12 The layout which uses the open loop system is shown in Figure D 14 Two parallel circuits are set up to connect all signal faces and pedestrian push buttons to the controller A closed loop system may be achieved by adding a cable between Posts 4 and 5 This helps to restore the service quickly in the event of a breakage elsewhere in the loop However this cable would not normally be terminated at Post 5 as it would affect the lamp monitoring The vehicle detectors are connected to the controller separately via screened feeder cables The cable size is chosen to provide sufficient cores to cater for signal requirements with adequate spares The circuits are arranged to achieve the most economic solution in terms of cable size and length and the assoc iated costs of ducting under the prevailing site conditions and existing services Adequate spares in cores must be provided in each cable for possible future expansion The cable size is chosen to provide sufficient cores to cater for signal requirements with adequate spares APPENDIX D WORKED EXAMPLE In view of the above considerations the first circuit caters for Posts 1 to 4 the second circuit caters for Posts 5 to 10 D 5 3 Selection of Controller Settings The results of the signal timing analysis for Design 2 Section D 4 can be used in conjunction with the method described in Append
322. tersections in a common coordination area Section 73 9 3 Selection of Appropriate Control The selection of signal control appropriate for a part icular site is based upon the following criteria a facilities b capacity c operation and maintenance and d cost and availability 9 3 1 Facilities The various control facilities available in the signal con troller determine the nature duration and sequence of signal displays As the number of control facilities required increases the controller logic becomes more complex 70 9 3 1 1 Sequence Selection Facilities a Fixed sequence This provides for a fixed duration of signal display to be allocated to each approach cyclically The sequence never changes and this is the minimum sequence facility available b TZ Skipped sequence traffic actuated This sequence provides for automatically altering the duration of signal displays in accordance with the measured traffic demands Phases or groups are designated to run in a predetermined sequence Phases can be skipped if there is no demand for them when it is their turn in the sequence c Variable sequence This provides for phases to be run as soon as possible in the sequence subject to a priority of movements and termination of conflicting groups Rather than use predetermined data this system uses the most recently measured traffic data fed into the system via traffic detectors This seque
323. the advance detectors Careful site observation is required under a range of conditions especially where lane utilisation varies It is recom mended to allow for an increase for upgrade and a decrease for downgrade at the rate of 0 1 second for each per cent of road grade The Maximum Variable Initial Green Setting limits the additional minimum green time Variable Initial Green time determined by increments The value of this setting depends on the distance of advance detectors from stop line For example if the distance is 50 m then for an average spacing of 7 m per vehicle 7 vehicles will store between the detectors and the stop line in each lane Using a start loss of 2 seconds for the first vehicle at the start of the green period and assuming that a car leaves the queue every two seconds the required setting is 2 7 x 2 16 seconds If the Basic Minimum Green Setting is 6 seconds then the required Maximum Variable Initial Green setting is 16 6 10 seconds Again careful site observation is required to ensure that there is sufficient Variable Initial Green time so that vehicles queued beyond the detectors can move over them and thus extend the phase C 4 3 Maximum Extension Green Setting The Maximum Extension Green Setting is used to control the maximum green time available to each phase or signal group when conflicting demands exist and when operating in the isolated mode see Section 13 3 This setting determines the d
324. the design 2 4 Crash Data Crash data should be obtained to identify hazard problems with the existing geometry or special problems for which traffic signals should cater Crash data for this purpose are best shown as collision diagrams and it is usual to show data for at least three years See Austroads GTEP Part 4 Road Crashes 2 5 Future Developments During the design of traffic signal installations it is desirable to consider potential changes to traffic demand patterns resulting from changes to land use and future traffic growth in the area of the intersection A design life analysis should be carried out to investigate the amount of traffic that can be accommo dated by the intersection in future years This will determine the adequacy of the geometric layout and phasing It will also identify future needs for additional road space and more complex phasing including associated lanterns and detection The design should take account of these changes particularly with regard to ducting arrangements AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 3 Geometric Elements 3 1 General This section deals with aspects of intersection geometry that are specific to signalised intersections For a more detailed treatment of intersection geometry refer to Austroads GTEP Part 5 Intersections at Grade When designing traffic signals for installation at an existing intersection it is important to identify and rectify de
325. the signal face should be located i as near as possible to the ideal location and ii so that necessary safety clearance from the obstruction are maintained 7 4 4 Pedestrian Signal Faces The following requirements apply for signalised cross ings at intersections and midblock locations Also see Section 7 5 2 4 on midblock signalised crossings a A pedestrian signal face must be provided at each end of a signalised crossing It should be located within 1 metre of the projection of the crosswalk lines and aimed at the opposite end of the crossing see Figures 7 2 b 7 4 a 7 6 7 8 7 9 b If the crossing width exceeds 10 m two pedestrian signal faces should be provided at each end of the crossing see Figure 7 4 b If the crossing distance exceeds 25 m supplementary pedestrian signal faces should be installed on a median island where practicable c d The pedestrian signal face should be located and if necessary screened to ensure that it is obvious which crossing is controlled by the signal face e Where a crossing is staged as two separate movements each stage must be signalised as a separate crossing with due regard to d above 53 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Figure 7 4 Pedestrian signal faces pedestrian arrow orientations shown in a and b indicate options available generally a Intersection Signalised Crossing in this
326. thod for determining the Maximum Variable Initial Green and Increment Settings is given in Ak elik 1995b Appendix B C 4 2 1 Basic Minimum Green Setting With stop line detectors the minimum green time is equal to the Basic Minimum Green Setting A longer minimum green display is required when advance detectors only are used as explained in Section C 4 2 2 A minimum green time is needed to ensure that the green signal circle or arrow is displayed for a safe minimum time i e not less than 5 seconds This is to provide enough time for a stationary vehicle at the stop line to begin moving and enter the intersection At a 128 particular site there may be a need to increase the minimum green time to allow for heavy vehicles a steep upgrade pedestrians or clearing of turning traffic Typical Minimum Green Settings used in practice with stop line detectors are shown in Table C 2 C 4 2 2 Increment and Maximum Variable Initial Green The Increment and Maximum Variable Initial Green Settings are applicable when only advance detectors are used Each vehicle arriving against a red signal adds a small amount of time equal to the Increment Setting to the minimum green time This provides sufficient green time to enable those vehicles stored between the detector and the stop line to clear the intersection Typical Increment Settings are in the range 0 5 to 2 0 seconds depending on the number of approach lanes and the location of
327. through a red circle display after first stopping at the stop line pro vided it is safe to do so sign R2 20 shown in Figure 11 9 See Section 15 12 for detailed discussion on Left Turn On Red This sign is mounted below the primary signal face A supplementary sign should also be mounted below the tertiary signal face if drivers have difficulty seeing the sign at the primary signal position when stopped at the stop line Figure 11 10 Hook Turn Only sign M RIGHT TURN FROM LEFT ONLY Figure 11 9 LEFT TURN ON RED PERMITTED AFTER STOPPING R2 20 sign LEFT TURN ON RED PERMITTED AFTER STOPPING 11 3 10 Traffic Signal STOP Sign The Traffic Signal STOP sign Figure 11 11 is used to indicate that a driver approaching a signalised inter section where traffic signals are blacked out or flashing should stop and give way to traffic as if the sign were a stop sign at an intersection without traffic signals This sign is erected on the traffic signal post carrying the primary signal faces Figure 11 11 Traffic Signal STOP sign AUSTROADS 79 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS 11 3 11 Warning Signs The symbolic Signals Ahead sign sign W3 3 shown in Figure 15 1 in Section 15 2 is required where i the sight distance to the signal stop line or to the back of the stationary queue at the signals is less than the stopping sight distan
328. time and t all red time Yellow times are calculated using Equation C 4 2 Appendix C with v 60 km h t 1 5 s ag 3 0 m s and the grades shown in Figure D 1 The resulting yellow times are t 4 8 s for South 5 1 s for North 4 3 s for East and 4 0 s for West approach Intersection widths used for all red time calculations are 13 m for North South movements and 25 m for East West movements and the corresponding all red times from Equation C 4 3 are t 0 9 and 1 8 s respectively Thus the use of 6 0 s is adequate for all approach movements The minimum green times are 8 s for Phases A and B see Table C 2 subject to pedestrian minimum time requirements discussed in point g below Normal start loss values are 3 seconds Left turning and right turning vehicles that conflict with pedestrian movements are assumed to experience a further 8 seconds delay Therefore the start loss values for turning vehicles will be 11 seconds This will impact left turn traffic performance significantly for South North and West approaches but will have less effect on right turn traffic not used for West approach since start losses due to opposing traffic queue clearance intervals are likely to be longer than 11 seconds f The pedestrian Walk period is selected as 6 seconds for all movements The pedestrian clearance times are determined by aaSIDRA using Equation C 5 2 Appendix C with pedestrian clearance speed of 1
329. tion b ensure uniformity of format c promote displays that are simple and easy to comprehend d prevent unsafe or conflicting displays e prevent unsafe sequence of displays and f ensure appropriate number of lanterns with a view to minimising the cost 5 1 2 Definitions The following definitions are important in under standing the presentation in this and other sections of this guide Signal aspect is a single optical system on a signal face capable of being illuminated at a given time Signal display is an aspect that is illuminated Signal face refers to a set of signal aspects in a common assembly generally in one or two columns placed together with a target board to improve signal visibility facing traffic from one direction Signal lantern refers to an assembly of optical com ponents one or more aspects together with the means of connecting them to power supply and facilities for mounting the complete assembly 5 2 Signal Face Elements 5 2 1 Signal Aspects Signal faces are made up of a number of signal aspects generally in one or two columns Their nature is described in AS 1742 Part 14 and design and recom mended size of signal aspects including shapes of symbols are given in AS 2144 5 2 2 Colour of Aspects Vehicle aspects shall be red yellow or green Pedestrian aspects shall be red or green Bicycle aspects for two aspect lanterns shall be red or green and for three
330. tion is used for offset calculation only and is not necessarily the critical intersection The offset is determined by the distance between signals the progression speed along the section of road between signals the sources and flow rates of vehicle platoons entering from the upstream intersection flows entering and exiting midblock platoon dispersion char acteristics and the queue of vehicles waiting at the downstream signal Ideally offsets should minimise the need for a platoon to vary its progression speed and should maximise the number of vehicles arriving at the downstream signal during the green period considering all vehicle move ments However offsets are usually selected to obtain good progression for major movements Basic strategies for determining offsets are discussed in Section 13 2 2 AUSTROADS COORDINATION OF TRAFFIC SIGNALS In addition to the three fundamental parameters dis cussed above alternative signal phase sequences should be considered to achieve improved signal coordination Lowrie 1996 13 2 2 Offset Strategies There are four basic offset strategies for coordination along a route These are i coordination of the starting offsets i e the beginning of green periods at all signals ii coordination of the finishing offsets i e the end of green periods iii simultaneous offsets i e the green periods start at the same time and iv maximum bandwidth i e maximise the amount
331. traffic signal controller depends on the type of control used Different types of signal control for isolated non coordinated intersection operation are discussed in this section For further discussion refer to RTA NSW 1991 1992 FHWA 1996 and Akcelik 1995b Types of coordinated signal operation are discussed in detail in Section 13 4 9 2 1 Traffic Actuated Control Traffic actuated control allows a variable sequence and variable duration of signal displays depending on traffic demands This type of control is also referred to as fully actuated since all movements phases are actuated in contrast with semi actuated control described in Section 9 2 3 Although fully actuated control has been the most common type of control traditionally the use of SCATS Master Isolated control described in Section 9 2 2 has found increased use in Australia 9 2 2 SCATS Master Isolated Control Where an intersection controller is linked to a SCATS regional computer Lowrie 1982 1990 1996 2001 it may be run under normal fully actuated control or SCATS Master Isolated SMI control as alternative forms of isolated non coordinated control Figure 9 1 Typical interfacing requirements for traffic signal controllers Inputs Vehicle detectors Pedestrian pushbutton switches Outputs Signal lanterns vehicle and pedestrian Pedestrian demand indicators TRAFFIC SIGNAL External coordination facilities
332. traffic to comply with regulatory requirements If the yellow interval is too short vehicles within a certain distance from the stop line will be unable or unwilling to stop before the red signal appears and if the yellow time is too long motorists will tend to abuse the signal As Gazis Herman and Maradudin 1960 have shown an inappropriate choice of yellow time can place an approaching driver at the onset of the yellow signal in the predicament of being too close to the intersection to stop safely and comfortably and yet be too far from it to clear the conflict area or even reach the stop line before the red signal appears This phenomenon is related to approach speed and is generally analysed in terms of the dilemma zone The yellow time should be just sufficient to enable a driver approaching at the design speed who is unable to stop in advance at the stop line to cross the stop line before the red signal appears In other words the duration of the yellow signal is dictated by the needs of the driver who requires the maximum deceleration acceptable to the majority of the population say 85 per cent This criterion ensures that drivers travelling at or below the speed limit will not be caught in the dilemma zone and that the yellow interval is no longer than necessary Thus the yellow time should be equal to the sum of the driver s reaction time and the time to reach the stop line at the design speed vp AUSTROADS This c
333. trian phase AUSTROADS SIGNAL PHASING may be considered During an exclusive pedestrian phase all Walk displays and associated clearances are shown simultaneously while all vehicle move ments are stopped by red signals In a scramble crossing phase pedestrians are allowed to walk in any direction including diagonally across the intersection within the limits of the crosswalk lines However exclusive pedestrian phases should be avoided as they normally create longer delays to vehicles and pedestrians compared with parallel pedestrian vehicle phasing arrangements Reintroduction or late introduction of a pedestrian movement Walk display may be used subject to sufficient time remaining in the phase to provide adequate Walk and Clearance times Where reintroduction or late introduction is used it is recommended that consideration be given to terminating conflicting vehicle turning movements Slip Lanes Pedestrian movements across a slip lane channelised left turn carriageway should be signalised where warranted by pedestrian volumes or when pedestrians require additional protection due to special conditions vehicle speed sight distance pedestrian disabilities Generally signals should be provided on a slip lane consisting of two or more lanes In some jurisdictions two aspect red yellow signals are used for slip lanes with one or more lanes In this case the left turn movement is subject to nor
334. tuated controllers with a high degree of efficiency The presence of an upstream signalised intersection or midblock signalised crossing alters the arrival pattern from random to platooned flow This enables improved traffic flow to be achieved if the green display is arranged to coincide with the arrival of the platoon The closer the traffic control signals are spaced the more platooned less random the arrival patterns become and the greater the opportunities are for im proved efficiency afforded by coordination Generally benefits result from coordination when traffic signals are provided at successive intersections spaced less than one kilometre apart At spacings of less than 500 metres the reductions in delays and stops usually exceed 20 per cent Bastable 1980 Most studies of installed coordination systems both fixed time and adaptive have shown the systems to be highly cost effective 13 4 Types of Coordination There are numerous options available for signal co ordination These options fall into three basic categories in terms of hardware architecture Lowrie 1996 2001 i local interlinking cable ii synchronous cableless linking and iii wide area control systems These are discussed in Sections 13 4 1 to 13 4 3 13 4 1 Local Interlinking These systems comprise a small number of closely spaced signals interconnected by a cable which allows the operation of one signal to affect the operation of t
335. ty and Occupancy Ratios B 3 4 Basic Relationships at Traffic Signals Appendix C Signal Timings C 1 Introduction 4 4 4 4 4 4 C 2 Signal Timing Methods C 2 1 Green Times and Cycle Time C 2 2 Maximum Tolerable Delay C 3 Actuated Controller Operation 00 00 0000 00 cee ee C 3 1 Vehicle Phase Intervals 23 244 geek desde dee a n e eir eae C 3 2 Pedestrian Intervals C 3 3 Actuated Controller Settings C 4 Vehicle Settings C 4 1 Late Start SEMINE motri osse e boc Le pe Lie ie ic bad io C 4 2 Minimum Green Setting C 4 3 Maximum Extension Green Setting C 4 4 Gap Setllg Siiip edi iie Ana seeds ne eds uae eine RR d de a C 4 5 Early Cut Off Green and Early Cut Off Yellow Settings C 4 6 Vehicle Clearance Settings C 4 7 Other Vehicle Settings C 5 Pedestrian Settings C 5 1 Pedestrian Walk Time
336. ulating directing warning or guiding traffic Traffic Count The process of determining the number of vehicles or pedestrians passing a given point or points during a specified period of time Also see Demand Flow Demand Volume Flow Rate Traffic Volume Traffic Demand see Demand Traffic Flow see Traffic Volume Traffic Island A structure on a road to direct traffic but does not include a Road Marking or Painted Island Traffic Responsive Plan Selection A signal coordination method that introduces pre determined plans by means of algorithms that respond to changing traffic conditions using data collected from detectors Traffic Sign A board plate screen or another device whether or not illuminated displaying words figures symbols or anything else to regulate direct or warn road users and includes a children crossing flag a hand held stop sign a parking control sign and a variable illuminated message sign but does not include traffic signals AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 Traffic Signal A signal that controls vehicle and pedestrian traffic at an intersection or on a road by means of red yellow green or white light displays and includes circular and arrow signals pedestrian signals bicycle crossing signals B bus and T tram signals overhead lane control signals and twin red or yellow signals Traffic Volume The number of vehicles or pedestrians passing a given point
337. uld be located centrally in the median or on wide medians the post should not be located more than 2 m from the relevant kerb face 7 5 2 Longitudinal Post Positions 7 5 2 1 Cross Road Intersections Figure 7 1 i Primary Signal Faces Posts for primary and dual primary signal faces should be placed between the projection of the adjacent stop line and up to a distance of 3 metres downstream They should not be placed upstream of the adjacent stop line except as provided for in Section 7 5 7 d or on the departure side of a signalised crossing Posts should be placed not less than 1 2 m from an island nose AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 ii Secondary Signal Faces Secondary signal faces are usually placed on the primary post or dual primary post if there is a median of the opposite approach iii Tertiary Signal Faces Posts for tertiary signal faces are preferably placed on the projection of the building alignment or at the tangent point of the curve where large radius curves are used or a minimum of 2 m from the corner and 1 m from adjacent edges of the triangular island formed by a separate left turn lane LOCATION OF SIGNAL EQUIPTMENT 7 5 2 2 Separate Controlled Lanes Within an Intersection i Primary Signal Faces Posts for primary and dual primary signal faces are located as described in Section 7 5 2 1 i except that one of these posts should be located at least 6 m beyond the stop
338. uration of the extension green interval see Figure C 1 AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 Maximum green time is the sum of minimum green time Section C 4 2 and the Maximum Extension Green Setting In some controllers a Maximum Green Setting equivalent to the maximum green time is used As seen in Table C 2 typical Maximum Extension Green Settings used in practice are 10 to 85 seconds for through movement phases and 5 to 25 seconds for arrow controlled right turn phases The maximum green times should be determined with the objectives of ensuring equitable distribution of green time amongst competing signal groups move ments and achieving optimum traffic performance e g minimum delay stops or queue length considering different traffic demand periods This is a key parameter for optimising the performance of actuated traffic signals When determining maximum green times a balance needs to be achieved between i erring on the long side considering that the Gap Setting should reduce the green time if necessary and ii large maximum green time values for individual phases or signal groups can add up to unduly long cycle times resulting in intolerable delay see Section C 2 2 The optimum values of maximum green times produced by an appropriate software package could be used as a guide to determining the Maximum Extension Green Settings with the above criteria in mind Maximum Extension Gre
339. urn arrows red yellow green in a six aspect signal face or by two aspect right turn arrows yellow green in a five aspect signal face see Figures 5 4 and 5 7 in Section 5 This phase sequence can be used where a two phase system Figure 6 2 has safety or efficiency problems with filter right turn operation In the case of cross roads the lagging right turn phasing is a suitable option only where the right turn from the direction opposing the lagging right turn right turn movement from the East approach in Figure 6 5 can be banned or other measures can be taken to ensure the safety of this movement This is because the filtering right turn vehicles would face a yellow circle display while the oncoming through traffic from the West approach in Figure 6 5 faces a green circle display during the phase transition from Phase A to Phase B in Figure 6 5 This situation also applies to T intersections with filter U turns In this case a driver who wants to turn right by filtering at the end of the first phase from the direction opposing the lagging right turn movement right turns from the East approach filtering at the end of Phase A in Figure 6 5 will see the signal display changing to yellow The driver may think that the signals change to yellow for the opposing traffic from the West approach in Figure 6 5 at the same time and therefore proceed and run into an opposing through vehicle for which the signal display would still
340. ussed in Section C 5 2 133 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS For pedestrian walking speed in Equation C 5 1 use the clearance speed Vow Vpc see Section C 5 2 Where pedestrian demands are high such as may occur in shopping areas signal timings for the intersection may be biased to favour pedestrians The pedestrian Walk Time can be increased in line with the green display for the parallel vehicle movements C 5 2 Pedestrian Clearance Time The purpose of the Pedestrian Clearance Time is to allow pedestrians who have stepped off the kerb at the commencement of the pedestrian clearance interval to complete their crossing with safety It comprises Clearance 1 and Clearance 2 Intervals as seen in Figures C 2 and C 3 The pedestrian clearance interval is implemented using Flashing Don t Walk display However during the intergreen interval terminating the phase the Flashing Don t Walk or Steady Don t Walk displays can be used as part of the clearance period except in some jurisdictions only the Steady Don t Walk may be dis played when filter right turns are allowed with parallel pedestrian movements As seen in Table C 2 typical Pedestrian Clearance Times used in practice are in the range 6 to 20 seconds The Pedestrian Clearance Time should be determined as follows i Calculate the total clearance time in seconds from t tV C 5 2 subject to t 5 where toe total pedestr
341. utes the major proportion of traffic in the circulating stream that causes a significant reduction in the capacity of the approach that has to give way to that circulating stream Ak elik Chung and Besley 1998 These signals are usually employed on a part time basis since they may be required only when heavy demand conditions occur during peak periods 99 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Two aspect yellow and red signals are used for round about metering as shown in Figure 5 6 a Section 5 3 4 The sequence of aspect display is Off to Yellow to Red to Off When metering is not required neither aspect is displayed Figure 15 3 shows the use of metering signals at a roundabout The signalised approach is referred to as the metered approach and the approach with the queue detector as the controlling approach When the queue on the controlling approach extends back to the queue detector Section 8 3 4 3 the signals on the metered approach operate so as to create a gap in the circulating flow This helps the controlling approach traffic to enter the roundabout When the red display is terminated on the metered approach the roundabout reverts to normal operation The introduction and duration of the red signal on the metered approach is determined by the controlling approach traffic The duration of the blank signal is determined according to a minimum blank time require ment or extended by
342. vements Filter Turn Opposing Movement Priority Traffic That traffic which is allocated priority service at an intersection by the operation of signals It may include emergency vehicles or public transport vehicles Not to be confused with the term Priority Road Major Road for unsignalised intersections a road on which traffic has right of way over all entering or crossing traffic Progression Progression is a time relationship between adjacent traffic signals which allows vehicle platoons to be given a green signal as they pass through the sequence of intersections Queue A line of vehicles or pedestrians waiting to proceed through an intersection Slowly moving vehicles or pedestrians joining the back of the queue are usually considered part of the queue The internal queue dynamics can involve starts and stops A faster moving line of vehicles is often referred to as a moving queue or a platoon Reaction Time see Perception and Reaction Time Recall Feature A feature of traffic signal controllers whereby a demand is placed for a particular phase when no other demands are present and all approach timers have expired Also see Arterial Demand xxi Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC SIGNALS Red Arrow Drop Out A form of partial control that uses three aspect red yellow green right turn arrows on a six aspect signal face and extinguishes the red arrow for the adjacent green circle display to
343. verhead Signal Faces If overhead signal faces are provided the tertiary signal faces may be omitted Figures 7 9 b and c show examples of dual carriage way signalised crossings In the case of a narrow median the secondary posts are located closer to the stop line in order to provide more space for pedestrians to wait and move in the median area Figure 7 8 T intersection signal location a Without Signalised Crossings b With Signalised Crossing on the Left c With Signalised Crossing on the Right AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 Figure 7 9 Midblock signalised crossings a One stage Signalised Crossing b Two stage Signalised Crossing with Left hand Offset Wide median c Two stage Signalised Crossing with Left hand Offset Narrow median 7 5 3 Collision Risk Reduction Studies by Fox Good and Joubert 1979 show that poles at the intersection of major roads have the highest risk of accident involvement AUSTROADS LOCATION OF SIGNAL EQUIPTMENT Accidents involving traffic signal equipment contribute substantially to maintenance costs and signal outages Although traffic signal posts and controllers yield under impact their location on the outside of curves or near exit or entry points should be avoided if possible For unyielding traffic signal mast arms or sign gantry posts improvements to pavement skid resistance or location well back
344. x 0 1 m from the ground AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 c Orientation Where provided pedestrian push buttons shall be orientated as follows see Figure 8 6 i Orientated at the kerbside so that it is either perpendicular to the signalised crossing and facing away from the crossing or parallel to the crossing and facing towards pedestrians about to use the crossing Orientation according to one or other of these options should be consistent throughout the region ii In narrow medians one push button may be mounted on the median post with its face parallel to the signalised crossing d Arrow Legends An arrow legend should be included on the face of the push button assembly This is used to give guidance to people with visual disabilities The arrow should point towards the associated crosswalk lines as shown in Figure 8 6 i Where the face of the push button is at right angles to the direction of the associated cross walk lines the arrow legend should point up to indicate a straight ahead walk direction ii Where the face of the push button is parallel to the crosswalk lines the arrow legend should be horizontal pointing in the direction of the associated signalised crossing iii Where one push button is mounted in a narrow median the arrow legend should have a horizontal double headed arrow The face of the push button should be parallel to the crosswalk lines e Dist
345. x B More detailed discussion on this subject can be found in Ak elik Besley and Roper 1999 Accessed by AR M VICROADS on 02 Jun 2005 TRAFFIC DETECTION Figure 8 1 Basic traffic parameters relevant to measurements by a vehicle loop detector system in presence detection mode Vehicle positions at time tg Vehicle positions at time t 4 effective detection LOOP zone length L headway h occupancy time to Va space time t spacing L lt space Sap vehicle lt length gt l lt length Lj Lj DETECTOR SENSOR HH electrical output detector PRESENCE output DETECTION time tia tis Leading front end of vehicle A enters the detection zone Leading front end of vehicle B enters the detection zone Passage detection can only allow a measure of headway time The only additional information it can provide is the flow rate Presence detection can provide more information enabling more characteristics of the vehicle stream to be calculated For example besides indi cating continuing presence of a vehicle it allows deter mination of occupancy and space times as well as parameters such as the SCATS DS degree of satur ation Lowrie 1982 1990 1996 2001 Therefore presence detection is the preferred type of detection for traffic manage ment AUSTROADS 8 2 Types of Traffic Systems are required to detect the following types
346. y A three aspect column is used to control a bus phase A bus lane must be designated a bus only lane for at least 100 m on the approach to the stop line This is necessary to legally deny vehicles other than a public bus access to that length of lane Otherwise a vehicle could block the bus movement when a white B is displayed Other vehicles can legally enter a bus lane 98 up to 100 m before turning or leaving the road Signs and pavement markings can be used to designate a length of bus only lane The lane adjacent to the bus only lane must be marked with left turn and through arrows if it is a shared lane or left turn arrows only if it is an exclusive left turn lane This is essential to legally allow other vehicles to turn left across the bus only lane A single white B aspect must be in at least a four aspect signal face It is used to provide a priority start at the beginning of the phase in which other vehicles moving in the same direction as the buses operate A single white B aspect is needed only when the buses and vehicles in the adjacent lane merge on the departure A priority start is not necessary if the bus lane continues on the departure Conflicting movements between buses and other vehicles must be denied or non existent The only exception is a merge conflict on the departure It is important to remember that any vehicle classified as a public bus may use a bus or bus only lane The lane will not be used exclusivel
347. y by buses on a registered route at all times For example if a registered bus route continued left at a signalised intersection buses on that route would only turn left However other public buses in the bus only lane could proceed straight ahead or turn right when a white B is displayed This must be considered before using B aspects to control buses 15 5 2 Tram Priority Tram priority is controlled differently to bus priority Unlike buses tram direction is controlled by tracks either located in the centre lanes of a shared roadway or clear of the trafficked lanes in a centrally located tram reserve A three aspect column is used to control tram move ments in their own right of way to eliminate conflicts between trams and other vehicles and to provide tram only phases A single aspect white T and five aspect signal faces as shown in Figure 5 1 and Section 5 4 2 are used to provide tram priority for trams on shared roadways The five aspect signal face is used in conjunction with a tram actuated leading right turn phase to clear queued vehicles between the tram and the stop line The single aspect white T is used with tram only phases where trams are on a unique route Where trams use alternative routes white arrows are used to indicate the turning direction AUSTROADS Accessed by AR M VICROADS on 02 Jun 2005 15 5 3 Operation Public transport priority at traffic signals can be categorised as passive and active priority
348. yses assume actuated signal operation and signal coordination applies to some movements Section D 2 contains listings of the input data and output information required for timing and performance analyses of signalised intersections Sections D 3 and D 4 describe input data and analysis results for Designs 1 and 2 respectively Decisions regarding improvements to intersection design and operational conditions should be made con sidering a wide range of operating conditions There fore intersection timing and performance analyses should ideally be carried out for several typical flow periods including am and pm peak periods business hours medium off peak and light off peak periods For the purpose of this worked example conditions during one peak period only will be considered D 2 Input and Output Requirements D 2 1 Input Data The first step in timing and performance analyses of a signalised intersection is preparation of input data using an intersection layout plan and signal phasing design volumes and other information on traffic characteristics at the intersection The following is a summary of the input data for timing and performance analyses of signalised intersections a Geometric Data i Intersection configuration cross intersection T intersection etc ii For each intersection leg two way one way approach or one way exit signalised crossings and type one stage or two stage e bann
349. ysis Research Report ARR No 123 6th reprint 1995 ARRB Transport Research Ltd Vermont South Australia AKCELIK R 1995a Australian vehicle actuated control practice survey results Road and Transport Research 4 3 pp 63 70 AKCELIK R 1995b Signal Timing Analysis for Vehicle Actuated Control Working Paper WD TE 95 007 ARRB Transport Research Ltd Vermont South Australia AKCELIK R 1995c Signal Timing Calculation Methods for Vehicle Actuated and Fixed Time Signals Working Paper WD TO 95 020 ARRB Transport Research Ltd Vermont South Australia AK ELIK amp ASSOCIATES 2001a aaSIDRA User Guide Akcelik and Associates Pty Ltd Melbourne Australia AKCELIK amp ASSOCIATES 2001b An Investigation of Pedestrian Movement Characteristics at Mid Block Signalised Crossings Technical Report Akcelik and Associates Pty Ltd Melbourne Australia AK ELIK R BESLEY M and CHUNG E 1998 An evaluation of SCATS Master Isolated control Proc ARRB Transport Research 19th Conference Transport 98 CD pp 1 24 ARRB Transport Research Ltd Vermont South Australia AK ELIK R BESLEY M and ROPER R 1999 Fundamental Relationships for Traffic Flows at Signalised Intersections Research Report ARR 340 ARRB Transport Research Ltd Vermont South Australia AKCELIK R and BIGGS D C 1987 Acceleration profile models for vehicles in road traffic Transportation Science 21 1 pp 36 54 AK EL

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