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WYDOT TRAFFIC STUDIES MANUAL March 2011

1. Ss SS 5 LIEU pi ERU P CD 8 ze gole LLLLLLLLLLELLLL AeA Ceu lll Il LE pr sy 5 5 2 2 lt Ay XXL AAV lll ak SITW SERRE ER eee eee A T T AAAA VAA A ye ji 1 1 ttt VV JAA VA 1111 1 1 YY cu i tilii Tit tt TT AVY AVY LV NS Abe Ane LL SPEED STUDY DATA COLLECTION SHEET Wyoming Department of Transportation J Figure 13 2 Example of a Completed Speed Study Data Collection Sheet WEATHER _C gar 9 44 72 _ jl I L LL L sm _ POSTED SPEED DIRECTION OF TRAVEL OBSERVER Form TR 10 DATE March 9 2011 Page 88 TRAFFIC STUDIES MANUAL 6 13 4 1 2 3 4 5 6 7 9 The Speed Study Data Collection Sheet can also be used to document speeds based on vehicle class either by direction or for both directions This is accomplished by utilizing one letter classification codes rather than tally marks Classification codes that may be used include the following P passenger vehicle includes cars pickups vans and SU
2. 122 STAGE 3 2 EXPECTED TRAFFIC FLOW RELATED IMPACTS 122 STAGE 5 5 JURISDICTION RELATEL te duda 125 STAGE 3 4 ANTICIPATED STRENGTH OF OPPOSITION SUPPORT FOR SIGNAL REMOVAL 126 STAGE 3 5 FINAL DECISION asa ay maan ban usa w 126 CHAPTER 17 PREEMPTION This chapter is under development 145 CHAPTER 18 AUXILIARY LANE AND TRAFFIC IMPACT STUDIES 147 Is PURPOSE qaku ashaku UE ere hus 147 182 AUXILIARY LEF I TUKN LANES asua mia aka O Mode ren 147 D Z u sau 147 18 2 2 URBAN AND FRINGE AREA GUIDELINES 148 15 3 AUXILIARY RIGHT TURN LANES tea eet Su oes 150 184 OFFSET RIGHT AND LEFT TURN LANES 152 183 AUXILIARY TRUCK CLIMBING LANES EEEE E E 153 1802 AUXILIAR YF ANG LAIN ES usu a A E E 153 18 7 AUXILIARY RIGHT TURN ACCELERATION LANES 154 18 8 REVIEW
3. No No No No No No No No No No No No No No Vl DIR East South East South East South North West West North South South North East West North West North North West North West South South South West Southe Northw North East East West East South South South North south Vl MANEUV Straight Straight Straight Turning L Turning R Turning L Turning L Turning R Straight Turning L Turning L Straight Straight Straight Straight Straight Turning L Straight Straight Turning L Make U Tu Backing Turning R Straight Straight Straight Turning L Turning L Straight Straight Straight Backing Straight Overtakin Stopped i Straight Turning R Turning R Page 45 V2 DIR East East East North North North South West West South North North North East South North South North North 10 North East South South East West North South North East Fast East East South South East West South VZ MANEUV Straight Straight Straight Straight Stopped i Straight Straight Stopped i Stopped i Straight Straight Stopped i Stopped i Stopped i Straight Stopped i Straight Stopped i Stopped i Non motor Straight Stopped i Turning R Stopped i Turning R Stopped i Straight Straight Straight Stopped i Stopped i Stopped i Straight Stopped i Turning R Stopped i Stopped i Turning R 15 Motor Moto
4. Data First Interval 15 00 2 25 15 Minutes Last Interval 30 Minutes 15 45 2725 t BD Minutes t Grand Total Options Print Comments Empty Intervals Print Peaks Iw Hide Empty Intervals Intersection Drawing Wording Intersection Photo m Do Print Headings Hide Header Information Preview Print Save Print Defaults Close Help Figure 9 2 gives an example of the output from a multi direction gap study showing the gaps for each direction as well as the total combined direction gaps For divided roadways with sufficient median width for storage to accommodate two separate crossings a multi direction gap study should be performed so the gap size can be determined for each direction of vehicular travel TRAFFIC STUDIES MANUAL Page 52 March 9 2011 Figure 9 2 Example Multi Direction Gap Study Output Wyoming Department of Transportation Traffic Program Safety amp Studies Section Cheyenne WY Intersection 4th amp Hamilton File Name hamiltongap Counted by LR Site Code 00021304 Weather Cool otart Date 4 31 2009 Comments Signal Turned Off Page No 1 Direction NB 4th St Start Time Volume 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 229 Int Total Average Factor 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
5. 4 TWO WAY STOP _ Le an m ER 700 7 E de INTERSECTION TOTAL STOPS STOPS HOUR Ar ae NN NN BN NE SIDE ROAD VOLUME PER APPROACH VPH TRAFFIC STUDIES MANUAL Page 134 TOTAL INTERSECTION FUEL CONSUMPTION GAL PER HR TOTAL INTERSECTION EXCESS FUEL CONSUMPTION we 7 M w r xP 4 IO WF Iv Pd lt rs LEGEND SIGNAL 999999299595 TWO WAY STOP SIDE ROAD VOLUME PER APPROACH VPH March 9 2011 Figure 16 11 Idline and Total Delay T Intersection Two lane Major Two lane Minor INTERSECTION TOTAL IDLING DELAY INTERSECTION TOTAL DELAY LEGEND SIGNAL LEGEND SIGNAL TWO WAY STOP TWO WAY STOP 6 40 EN E INTERSECTION TOTAL IDLING DELAY VEH HRS PER HR INTERSECTION TOTAL DELAY VEH HRS PER HR SIDE ROAD VOLUME PER APPROACH VPH SIDE ROAD VOLUME PER APPROACH VPH TRAFFIC STUDIES MANUAL Page 135 March 9 2011 Figure 16 12 Stops Excess Fuel Consumption T Intersection Two lane Major Two lane Minor TOTAL INTERSECTION INTERSECTION TOTAL STOPS EXCESS FUEL CONSUMPTION M u 52 INTERSECTION TOTAL STOPS STOPS PER HOUR TOTAL INTERSECTION FUEL CONSUMPTION GAL PER HR 50 100 150 200 250 300 0 100 150 200 250 300 SIDE ROAD VOLUME PER APPROACH SIDE ROAD VOLUME PER APPROACH VPH TRAFFIC STUDIES MANUAL P
6. tant 28 WOUARRANEIEAG PEDESTRIAN VOCUME u u l 28 342 WARRANT SCHOOL CROSSIN G 5 28 TRAFFIC STUDIES MANUAL Page i March 9 2011 313 WARRANT 6 COORDINATED SIGNAL SYSTEM 28 m4 u u uu uu EU 29 345 WARRANTS ROADWAY NETWORK 29 3 16 WARRANT 9 INTERSECTION NEAR A GRADE CROSSING 29 CHAPTER TURNING MOVEMENT COUN BD aa pou ukana kS uqa Saa uiay sa 31 4 1 PURBO iurc 31 4 2 MANUAL TURNING MOVEMENT COUNT iei oet ebeb eie tope ee 31 4 3 AUTOMATED TURNING MOVEMENT COUNT L 3 CHAPTER haya sasa 33 5 1 LTO Eu arte ree Ed DINE LIN M MM I NM 33 22 COMPLETING THECONDITION DEAGHR AM 33 CHAPTER O SIGHEDISTANCESIUDIES asua ipu a aA Ne uade
7. 7 8 9 10 indicate the appropriate color of line to use to plot that hour s data Due to scale of the figure and inherent errors in plotting the points some positive numbers will show as blue to indicate that the point 1s on or nearly on the curve but not above the curve as required for the warrant to be met The table also indicates how long the associated horizontal and vertical lines need to be to accurately represent the respective volumes on the figures e Determine the four highest points to be plotted on the Four Hour Warrant curves from the four highest numbers under the Volume Above Below Criteria heading The color coding will indicate how many points will be plotted in each color Delete the extra horizontal and vertical lines leaving just four horizontal and four vertical lines of the appropriate colors f Set the length of each of the lines by right clicking on the line selecting Size and Properties and entering the length of the line from the table to the right of the figure Set the length of line for horizontal lines in the Width field and for vertical lines in the Height field Copy B Paste Edit Text H dh Bring to Front b Send to Back gt Assign Macro Set as Default Shape W Format Shape e Move each of the horizontal and respective vertical lines into their appropriate locations on the figure to accurately represent each of the plot
8. In built up area of isolated community of lt 10 000 with no existing signals WARRANT 1 Eight Hour Vehicular Volume Condition Minimum Vehicular Volume WARRANT SATISFIED YES APPROACH WARRANT LANES VOLUME Kae Se S Mino Ste 9 Fe e e Minor Street 109 1 Warrant Volume Met No Yes Yes Yes Yes Yes Combination of Conditions A and B BOTH SATISFIED YES Condition A SATISFIED YES mE WARRANT VOLUME 114M 12 PM 3PM 4PM S PM Both Aporcaches 25 1272 or pe Pete e e m e Warrant Volume Met No No No Yes Yes Yes Condition B B SATISFIED YES NO mem 2 ma z ww ug 1000 See Highest Approach 22 gt Minor Sireet a ES ne Yes ves Yes Warrant Volume Met Yes Yes Yes Yes Yes TRAFFIC STUDIES MANUAL Page 20 March 9 2011 Figure 3 2 Example Traffic Signal Warrants Worksheet Page 2 of 6 gn ares Sr Sage 2 of WYOMING DEPARTMENT OF TRANSPORTATION TRAFFIC SIGNAL WARRANTS WARRANT 2 Four Hour Vehicular Volume SATISFIED am MO 11 AM LPM 3 PM T vos TT roe tre 0 Does platted point fall above curve an Figure 40 17 We Ma Na No pari Yea Refer
9. Intersection Related Rear Front Normally Backing West Backing Motor Vehicle In Transport on Roadway Dry LUnkrmawri MAIM ST East Stopped In Traffic Motor Vehicle In Transport on Roadway Ho Improper 1272108 1202 210913480 STH STAY 336 Intersection Angle Frond ta Side Includes East Siraight Ahead Motor Vehicle In Transport on Roadway Dsayilighit Dry Ran Red Light MAIN ST Eat Straight Ahead Motor Vehicle In Transport an Roadway improper Driving 09 15 2009 1129 200913870 NM MAIN ST Intersecton Related Sideswipe Same Direction Passings South Overtaking Passing Motor Vehicle In Transport on Roadway Daylight Dry Improper Passing 5TH STANY 330 South Stopped In Motor Vehicle In Transport an Roadway improper Driving 10302002 823 200918187 MAIN Intersection Angle Front ta Side Oppasing South Stopped In Traic Motor Vehicle In Transport on Roadway Daylight Dry Other Impraper Action STH STANY 330 mn South Turning Right Motor Vehicle In Transport on Roadway improper Driving 12 06 2108 1104 200820230 STH STAY 33D 1 0 Related Rear End Front to Rear atraignt Ahead Motor Vahlele In Transport on Roadway Dxayilgnit Wal Following tao Close M MAIN ST East Siopped Trame Motor Vehicle In Transport on Roadway No improper Driving un 1443 2 01000 21 MAIN ST Intersection Angle Same Direction Franz ta Side Horih Turnirig Right Motor Vehicle I
10. b Combination Horizontal Alignment Advisory Speed sign W1 1a and W1 2a c One Direction Large Arrow sign W1 6 d Advisory Exit and or Advisory Ramp Speed Signs Additionally the warning can be enhanced with enlarged signing a TRUCK header panel flashing beacons and changeable message signs TRAFFIC STUDIES MANUAL Page 77 March 9 2011 This page Intentionally left blank TRAFFIC STUDIES MANUAL Page 78 March 9 2011 12 1 1 2 3 4 12 2 1 CHAPTER 12 NO PASSING ZONE STUDY PURPOSE The Department of Transportation is authorized by Wyoming Statute 31 5 207 to determine those portions of any highway under its jurisdiction where overtaking and passing or driving to the left of the roadway would be especially hazardous Those portions of the highway shall be marked with no passing zone markings The no passing areas include vertical and horizontal curves railroad grade crossings narrow bridges intersections transitions to and from multi lane sections of roadway and other locations where passing must be prohibited because of inadequate sight distance or other special conditions The requirements and details for the marking of no passing zones are contained in Chapter III of the WYDOT Pavement Marking Manual 2002 No passing zones that are not governed by passing sight distance e g railroad grade crossings narrow bridges intersections or transitions to and from multi lane sections shall be es
11. j j _ ttt ete te _ j j E _ eee 55 Meus _ EE pg 60 WERE UN ll I l l l 1 1 March 9 2011 13 5 1 2 3 4 5 6 7 9 DETERMINATION OF APPROPRIATE SPEED LIMIT Speed limits and speed zoning remain one of the more controversial tasks for the traffic engineering profession Engineers public safety officials and others involved in setting and enforcing speed limits may disagree on the appropriate balance between safety and road user convenience that should prevail on particular road segments considering conditions of topography weather adjacent activities and traffic Motorists other road users and roadway neighbors have their own perspectives on this balance and may or may not abide by the professionals judgments Wyoming speed laws define speed limits as absolute speed limits traveling at a speed above the absolute limit is by definition illegal and presumably imprudent and unreasonable WYDOT is empowered to lower or raise speed limits on a particular state highway segment if these altered limits are judged to be reasonable and safe under conditions found to exist at that location Engineering and traffic studies typically provide the basis for making such speed zone judgments These studies generally consider such factors as the physical features of the roadway crash experience traffi
12. 5 EIE m _ _ LL LL LLL gs L eee j TA j j pt tt tpt tT tt j db rs 20 3 TRAFFIC STUDIES MANUAL MILES PER HOUR Page 87 ppt 5 zo om E EE ES SE rmn EN j j L LE SEEN 200 tt j LLL LLLLLL ET LITE dn 2 lt LLL _ LLL _ j LL LLL LLLLLL March 9 2011 Em m sim mis EB ER RE 4 eee G6 EH RE GERI s RR EER ER DR CUR DE ERU E 2 E ER T a a P UR Rees F s s E eee V ER ERE DER RE 7 ER EE D 588065 E ERE B m B DS W m d ba E ER ER GT DR ER DR ees CRRA 0 BRERA S ae RE D RRA ene
13. 115 140 165 195 220 245 285 325 365 Source AASHTO Green Book 2004 OO O1 gt oO O O TRAFFIC STUDIES MANUAL Page 38 March 9 2011 2 3 4 5 6 Determine the minimum sight distance for the posted speed on each approach to intersection per Table 6 1 Sight distance measurements should be gathered for all legs of the uncontrolled intersection Traffic approaching from both the left and right should be considered for measurements The Observer records the date and time posted or operating speed site location and weather conditions on the sight distance diagram The measuring process is represented in Figure 6 6 and described below Figure 6 6 Sight Distance Measurement at Uncontrolled Intersection Assistant j Decision Observer Point Source CTRE The observer holds the sighting rod and the assistant holds the target rod They position themselves on two intersecting approaches at the appropriate stopping sight distances taken from Table 6 1 These are the X and Y dimensions The observer represents the approaching vehicle and is located at the decision point The observer uses the 3 5 foot sighting rod which represents the driver s eye height The assistant represents the intersecting vehicle The assistant uses the 4 25 foot target rod which represents the height of the approaching vehicle The observer sights from the top of the sighting ro
14. WYDOT TRAFFIC STUDIES MANUAL March 2011 WYDOT Traffic Program 2 WYDOT TRAFFIC STUDIES MANUAL MARCH 2011 TABLE OF CONTENTS CHAPTER INIRODUCTIONZu Z ene u uuu u A u au am anes eee 1 1 AUTHORITY sss den tn eee ee A es 1 1 BACKOROUND st onset 1 1 DISERIBUTIONu Su 1 1 1 uu aa au sag b sas 2 2 REVISIONS ANI ADDITIONS uuu Md 2 3 JO bl SAC CI uuu uu kunana nuna 2 CHAPTER TRAFFIC SIGNAL STUDY PROCEDURE uya agnata sasi biasa kaynata 3 2 1 PURPOSE M 3 2 2 LEARNING OF THE CONCERN Tu talit esie 3 2 9 OBSERVATION OF CONCERN SYMPTOMS 555 ee ake e 3 2 4 ESTABLISHING BASIC AREAS OF 4 VERNICE CE 4 22 PEDESTRIAN u editae Das Sau spa s doce s eed epa 4 CRASHES OE E asuy 5 2 5 DATA COLLECTION REDUCTION AND eren 5 2 6 DATA ANALYSIS AND INTERPRETATION ii eie eere a ene PER eed ERE S RM te E M E LE
15. a fene D lt c co jn e RIRIA 949 jo o o C C e eco e 200913480 200911777 gt gt 202909624 5 0705800 200920230 0608828 0722515 d ud 1 co io cC C clear filter Main St amp 5th St 01 01 06 08 14 10 A 201000621 0612268 CEE 0613469 0717222 NU 200800352 200810685 06 Y 0716529 0714507 X 0713099 0707749 Straight Stopped Unknown lt gt Backing lt Overtaking Sideswipe State of Wyoming DOT WY lt 02 1 TRAFFIC STUDIES MANUAL Erratic x Out of control Right turn x Left turn gt g U turn lt 5 2011 Page 44 0 accidents with insufficient data for dis Parked Pedestrian Fixed objects Bicycle General Pole Injury I d Fatality Nighttime 4 3rd vehicle DUI Extra data Intersection Magic ver 6 714 Pd Programming 2000 March 9 2011 Intersection Magic VER 6 714 State of Wyoming DOT Accident listing 01 01 2006 08 14 2010 Main St Sheridan amp 5th WY S bs WY Sorted by lt DATE TIME ACC gt CASE ID 0604184 0608826 0608828 0609193 0700760 0705800 0707685 0707749 0708100 0713099 0714507 0717222 0716529 07184891 0718750 0720837 0722515 200800352 200801008 200810685 200909631 200909624 400911777 2003123065 200913480 200913870 20091618
16. 7 30 7 45 etc as long as there is no overlap among warranted hours An engineering study should consider the effects of the right turn vehicles from the minor street approaches Engineering judgment should be used to determine what if any portion of the right turn traffic 1s subtracted from the minor street traffic count when evaluating the count against the signal warrants The following factors should be considered when applying engineering judgment to determine the portion of right turn volumes included in the minor street volume a Number of lanes on the minor street approach b Presence or absence of exclusive right turn lane c Presence or absence of free flow right turn lane d Availability of gaps in major street traffic e Sight distance available to right turning vehicles f Percentage of minor street traffic which turns right e Pedestrian volumes Section 3 4 Includes several Instances where right turn volumes would not be Included in the warrant analysis If free flow right turn lanes are present the right turn volumes should not be included in the warrant analysis This includes both free flow right turns from the major street right turn volumes deducted from the major street volumes and from the minor street right turn volumes deducted from the minor street approach volumes When a minor street approach consists of a single lane but right turn volumes exceed 50 of the total traffic on the approach so
17. are substantially reduced in width below desirable sections used in relatively open country Case CF L 4 Continuous freeway lighting is considered to be warranted on those sections where the ratio of night to day crash rate 15 at least 2 0 or higher than the statewide average for all unlighted similar sections and a study indicates that lighting may be expected to result in a significant reduction in the night crash rate Continuous freeway lighting should be considered for all roadway facilities in urban areas that have median barriers In rural areas each location must be individually evaluated as to its need for illumination 15 2 2 COMPLETE INTERCHANGE LIGHTING Case CIL 1 Complete interchange lighting may be warranted where the total current ADT ramp traffic entering and leaving the freeway within the interchange exceeds 10 000 for urban conditions 8 000 for suburban conditions or 5 000 for rural conditions Case CIL 2 Complete interchange lighting may be warranted where the current ADT on the crossroad exceeds 10 000 for urban conditions 8 000 for suburban conditions or 5 000 for rural conditions Case CIL 3 Complete interchange lighting may be warranted where existing substantial commercial or industrial development that 15 lighted during hours of darkness 15 located the immediate vicinity of the interchange or where the crossroad approach legs are lighted for 0 5 miles or more on each side of the interchange Case C
18. decision The public should be given notice of the intention to remove the traffic control signal Set a firm date for the turn off of the signals to occur and notify the public This can consist of news releases public hearings and or presentations at city council meetings This 15 a very important step and the District must be prepared to fully answer any questions that may arise How this phase is handled 15 critical since incomplete or insincere answers to those opposed to the signal removal could cause the whole process to fail Distribution of a news release to local newspapers radio and television stations can potentially provide the widest coverage when notifying public of the proposed removal When city council approval is required for signal removal press coverage of the council meeting will often have the same value as a news release However a news release prior to the council meeting is more likely to present the matter in a positive light whereas news coverage of the matter in city council may give more emphasis to any controversy or colorful statements of the opposition The major drawback to the release 1s that there 15 no guarantee that those residents commercial establishments and drivers most affected by the signal removal will receive the information The release should include information such as the intersection location the date and time that the signal 15 to go into the interim control mode what the new control will
19. fuel consumption and miles per gallon The data can also be used to produce a speed plot and or a time space trajectory plot These outputs must then be analyzed and engineering judgment should be applied to the numbers and graphs to determine if problem areas exist If they do then the appropriate corrective action must be determined Engineering judgment should be applied in order to analyze the results and to determine any actions that can be taken to reduce delay and improve operational efficiency Things to look for include a More than one stop between intersections This may indicate interference with the traffic flow from sources other than traffic signals possibly caused by traffic generators b Travel speed average speed significantly less than running speed This could be caused by delay at the traffic signals or accesses c Delay significantly higher during peak versus off peak periods This could be caused by heavy cross street traffic during a peak volume at an intersection exceeding or close to capacity lack of left turn lane storage capacity etc Typical solutions for delays would include turn lanes traffic signal retiming and restriction of certain movements responsible for delay The engineer must determine the best solution for each particular situation TRAFFIC STUDIES MANUAL Page 102 March 9 2011 Figure 14 1 Example PC Travel Field Worksheet Form TR 22 Revsed 11 17 08 PC TRAVEL FIELD WORKSHEET
20. x 22 x 22 x 22 4 MAINING 22 HOURS 8 954 13 2 30 8 3 520 2 Hrs 22 Hrs 2 Hrs 22 Hrs 2 22 2 22 2 22 24 HOUR TOTAL DIFFERENCE 15 6 356 4 080 10 562 PER VEHICLE IMPACTS Del Sec Veh Divide 24 Hour Differences by 24 Hour Vo ii 0 0025 TRAFFIC STUDIES MANUAL Page 129 March 9 2011 LE a 8 C o E 5 5 LL From Nomographs INTERSECTION TOTAL IDLING DELAY VEH HRS PER HR Figure 16 6 Example Idling and Total Delay Estimates Four Way Intersection Four Lane Major Two Lane Minor INTERSECTION TOTAL IDLING DELAY LEGEND L BE BE 4 TRAFFIC STUDIES MANUAL Page 130 INTERSECTION TOTAL DELAY VEH HRS PER INTERSECTION TOTAL DELAY LEGEND SIGNAL TWO WAY STOP 1 March 9 2011 Figure 16 7 Example Stops and Excess Fuel Consumption Estimates Four Way Intersection Four Lane Major Two Lane Minor TOTAL INTERSECTION INTERSECTION TOTAL STOPS EXCESS FUEL CONSUMPTION LEGEND SIGNAL TWO WAY STOP r AS d 5 L k X INTERSECTION TOTAL STOPS STOPS PER HOUR N TOTALINTERSECTION FUEL CONSUMPTION GAL PER HR 23 52 siDEROAD VOLUME PER APPROACH VPH Q3 52 sIDEROAD VOLUME PER APPROACH VPH TRAFFIC STUDIES MANUAL Page 131 March 9 2011 Figure 16 8 List of Nomographs by Intersection ILLUSTRATION NOMOGRAPH F
21. 00 0 Total Vehicle Count J Maximum Stopped Time Min Secs for Delay 674 Summary Information 4 00 00 PM 5 00 00 PM Through Vehicle Count 6 O 9 9 Maximum Stopped Time 13 Average Stopped Time 1197 5 1 08 Maximum Queue Min Secs for Delay O Summary Information 3 00 00 5 00 00 Through Vehicle Count O T 55 ed Tim Min Secs for Delay O 416 8 8 I 2 Maximum Queue 212 Delay in 0850 Total Delay TRAFFIC STUDIES MANUAL Page 48 File Name Pine amp TylerPM Site Code 00000003 Start Date 6 29 2004 Page No 1 March 9 2011 9 1 1 2 3 4 5 9 2 1 2 3 9 3 1 2 3 CHAPTER 9 PEDESTRIAN GAP STUDY PURPOSE The gap study is used to determine the size and the number of gaps in the vehicular traffic stream that are of adequate length to permit pedestrians to cross A gap is normally defined as the amount of time in seconds between when the end of one vehicle passes a point on the roadway and when the front of the next vehicle passes the same point You can measure gaps on the entire road with several lanes of traffic going in different directions or you can measure gaps on individual lanes It depends on the data that 1s required A pedestrian gap study consists of measuring the predominant pedestrian group size determining the length
22. 1 0 1 1 0 1 0 61 6 7 03 15 PM 159 12 19 11 7 10 6 1 3 1 1 1 0 1 0 1 74 6 7 03 30 PM 226 22 22 10 6 2 0 3 2 2 0 0 0 0 0 1 70 4 5 03 45 PM 182 11 18 15 4 8 3 3 1 1 0 2 2 1 0 1 70 6 7 Total 725 56 70 47 28 26 13 9 7 5 1 4 3 2 1 3 275 6 7 Grand Total 725 56 70 47 28 26 13 9 7 5 1 4 3 2 1 3 275 6 7 Total 20 4 25 5 17 1 10 2 9 5 3 3 2 5 1 8 0 4 1 5 1 1 0 7 0 4 1 1 TRAFFIC STUDIES MANUAL Page 53 March 9 2011 9 5 2 TOTAL COMBINED DIRECTION GAP STUDY 1 2 3 4 5 A total combined direction gap study be performed with either conventional stop watch with an electronic traffic data collector such as Technologies TDC 8 or TDC 12 There are two acceptable ways to measure the length of gaps using JAMAR Technologies TDC 8 or TDC 12 traffic data collectors They can be used to perform multi direction gap studies or total combined direction gap studies If the total gap 15 the only gap data needed the traffic data collector s standard gap study procedure can be used or the stop sign delay study can be adapted to measure the available gaps A total combined direction gap study can be conducted using the standard gap study procedure on the electronic traffic data collector by combining the multi direction data together This is accomplished through the PetraPro software analysis program by checking the combined tab under Combine Groups in the Gap Print Setup window Gap Print Setup Select I
23. 2 or more 500 1 Warrant 1 2 more Condition 2 or more 2 or more Zormore 60 Hormone 5 p _ 1 e 10 000 2 576 Combination 2 or more 504 2 576 1A amp 1B 2 2ormoe 720 504 12 000 8400 160 12 4800 1__ 2 600 420 10000 7000 160 112 4800 Box P Warrants for Traffic Control Signals Traffic Engineering November 1967 3 TRAFFIC SIGNAL WARRANTS WORKSHEET 1 The Traffic Signal Warrants worksheet is an Excel spreadsheet that has been developed to simplify the traffic signal warrant analysis procedure It is designed for the easy input of the volume data and pertinent intersection conditions and to compile the results In a clear and understandable format for use in justifying the installation of a new signal or the removal of an existing signal 2 This form summarizes data previously collected at the intersection This data 15 drawn from a larger set of data which can later be used to determine the proper design and operation should signalization be warranted 3 Most of the data entry for the Traffic Signal Warrants worksheet takes place on the Input Sheet fields should be filled In as applicable Figure 3 1 gives an example of the Input Sheet a It 1s important that the city name be entered and spelled correctly because the spreadsheet determines whether or not to apply the reduced warrant criteria based on the name of t
24. 33 13 PM 18 1 27 3 33 16 PM 3 33 27 PM 11 1 28 3 33 27 PM 3 33 32 PM 5 1 29 3 33 32 PM 3 33 58 PM 26 1 30 3 33 58 PM 3 34 02 PM 4 11 31 3 34 03 PM 3 34 16 PM 13 1 32 3 34 16 3 34 47 31 1 33 3 34 47 3 34 50 3 1 34 3 34 55 PM 3 35 01 PM 6 Summary Information 3 30 00 PM 3 35 00 PM Lane 1 Main at D Total Vehicle Count Total Gaps Measured 34 Delayed Vehicle Count Total Gaps Measured 34 Through Vehicle Count 0 Average Stopped Time Average Gap Size 8 24 Maximum Stopped Time Maximum Gap Measured 31 Min Secs for Delay 0 Average Queue An indication of amount of platooning 0 93 Queue Density 1 00 Maximum Queue 1 Delay in Vehicle Hour 0 93 Total Delay 280 TRAFFIC STUDIES MANUAL Page 56 File Name US26Dstgap Site Code 00051000 Start Date 4 31 2010 March 9 2011 9 5 3 AVAILABLE SURVEY 1 2 3 4 5 6 7 9 9 10 The number of adequate gaps for pedestrians to cross the roadway be determined based the calculation of the minimum adequate gap see Section 9 4 and the measurement of actual eaps available for the crossing location being studied To complete the available gap survey portion of the pedestrian gap study form note the beginning and ending times and total duration of the study in minutes Place a tick mark in the tally column correspondin
25. 9 1 amu 49 9 2 PEDESTRIANGAPSTUDYTORM yu E Mis 49 9 3 PEPDESIRPAN GROUP SIZE SURVEY u oli ote es 49 9 4 NINIMUM ADEOUATEGADP kau Sumu a usu 50 9 5 MEASURING GAP SDZES hs aaa aaa sua a AS a as 52 05 1 MULIFDIREC HON GAP uu u ua s 52 952 TOTAL COMBINED DIRECTION GAP STUD Y a n sob oppeto vs 54 25 AVAILABLE GAP SURVEY aeui eed MR EDU DID ss 57 TRAFFIC STUDIES MANUAL Page 11 March 9 2011 CHAPTER 10 sSIGNAL OPERATIONSSEUDIBSs u u S L uu u 59 ID TURPO UNE 59 107 CONTROLCER PHASING ve u 59 10 39 PEBPPSTIURNOPHERATION 60 04 LEFETURNPFHASING CRITERIA uu uu lu uu au au u 6 60 10 55 PROTECTED PERMISSIVE LEFT TURN PHASE CONTROL 61 106 FEDESTRIAN PHASES uu u u S 61 10 7 PEDESTRIAN CROSSING DISTANCE MEASUREMENLT 61 19 PRETIMED VERSUS ACTUATED CONTROL te eee
26. If an all way stop 1s to be used then in general a decrease in crashes could be expected If however two way stop control 15 planned then changes described above can be expected If a multilane roundabout is to be used the frequency of crashes could be expected to decrease slightly but the severity of crashes would be expected to be significantly reduced If a single lane roundabout is to be used a significant decrease in both frequency and severity of crashes would be expected TRAFFIC STUDIES MANUAL Page 113 March 9 2011 3 4 5 If the signal installation 15 relatively recent 1 five to ten years old and adequate crash data 15 available and where traffic volumes have not changed substantially during the life of the signal the crash records prior to the signal installation should be compared to those after the signal was installed a If the crash frequency or severity improved significantly after signalization removal should not be further considered b If the crash frequency or severity increased significantly after the signal installation the signal removal process should continue to the next stage c If crash patterns were unchanged or changed only slightly after signal installation alternative safety improvements may be considered in lieu of signal removal These alternative improvements include signal display upgrades increased signal clearance intervals if right angle crash frequency 15 high
27. Jet i T En ant P _ a i14 INTERSECTION TOTAL IDLING DELAY VEH HRS PER HR 0 100 200 250 300 SIDE ROAD VOLUME PER APPROACH VPH TRAFFIC STUDIES MANUAL Page 139 INTERSECTION TOTAL DELAY VEH HRS PER HR INTERSECTION TOTAL DELAY LEGEND SIGNAL TWO WAY STOP a E i I d LI _ 100 200 250 300 SIDE ROAD VOLUME PER APPROACH VPH March 9 2011 TOTAL STOPS STOPS PER HOUR Figure 16 16 Stops and Excess Fuel Consumption T Intersection Four lane Major Two lane Minor INTERSECTION TOTAL STOPS LEGEND ELEC TE SIGNAL e e J Lal i a a rad SIDE ROAD VOLUME PER APPROACH VPH TRAFFIC STUDIES MANUAL Page 140 TOTAL INTERSECTION FUEL CONSUMPTION GAL PER HR TOTAL INTERSECTION EXCESS FUEL CONSUMPTION LEGEND TWO WAY STOP SIDE ROAD VOLUME PER APPROACH VPH March 9 2011 INTERSECTION TOTAL IDLING DELAY HRS PER HR Figure 16 17 Idling and Total Delay Four way Intersection Four lane Major Four lane Minor INTERSECTION TOTAL IDLING DELAY LEGEND SIGNAL ae er x Ll SIDE ROAD VOLUME PER APPROACH TRAFFIC STUDIES MANUAL Page 141 INTERSECTION TOTAL DELAY VEH HRS PER HR INTERSECTION TOTAL DELAY LEGEND SIGNAL TWO WAY STOP p D L
28. Jo S A NA 102 CHAPTER 15 HIGHWAY LIGHTING STUDIES ee ke iessen ete eee 105 PURPOSE arna ENE ME 105 152 JEIGELEINCE WARKANIS A O O E 105 1924 CONTINUOUS FREE WAY LIGHTING u uu uyu Du N 105 15 27 COMPLETE INTERCHANGE LIGHTING a eese sapete a a E 106 1532 3 PARTIAL INTERCHANGE EIGINIINGi k meinen 106 JO TO NON FREEWA Y LIGHTING uqu uusha asan a ode aun hh kah 107 CHAPTER 16 TRAFFIC SIGNAL REMOVALSTUDY 109 PURPOSE E Lu 109 10 2 STAGES PRELIMINARY SCREENING esege aenn quedo che 109 162 4 SIGHT DISTANCE dei IPM a ss 111 10 22 SPECIAL SITE CONSIDERATIONS uu u u nasa bi Sae ep a Ue 111 162 WARRANT S cH 112 SSPECTATJESTIEICATIOLI S u uuu u u u intu Qu 112 163 STAGE 2 DETAILED REMOVAL JAINAL Y SIS iie its oreet oct pol otro dut on du pps cons 112 16 31 EXPECTED INFLUENCE ON CRASHES I ME 113 16 52 EXPECTED TRAFFIC FEOW RBIEATEDIMPAC 5 e utes eos eu 115 16 55 J
29. Observe each group as they enter the crossing Place a tick mark in the tally column corresponding to the number of rows in the group Stragglers are not included Groups will form naturally when gaps are inadequate to accommodate random arrivals When the sampling period is complete count the tally marks and record the frequency of each corresponding group size in the total column The sum of the total column will be the total number of groups sampled The remainder of the pedestrian group size survey portion of the form is completed by multiplying the total number of groups by 0 85 to obtain the number of groups at or below the 85th percentile group size The 85th percentile group size is the group size that contains that value Figure 9 1 gives an example of a completed pedestrian group size study MINIMUM ADEQUATE GAP Having calculated the 85th percentile group size the minimum adequate gap time G required for crossing the street can be found by using the following equation Equation 9 1 W G 2 N 1 3 Where G Minimum adequate time seconds W Width of roadway in feet S Assumed walking speed in feet second use 3 5 for students and 4 0 for normal pedestrian traffic 2 N 1 Pedestrian clearance time N Number of rows in 85 group size 2 Time interval between rows Headway in seconds 3 Perception and reaction Start up time in seconds This value is the minimum length in seconds of a gap
30. R SY FY OR mE Detector Extension Delay Appropriate Special Turning Movement Operation 4 or 5 Section Heads Y a Head Alignment Signal Faces Backplates Visors No Adverse Background Lighting Pedestrian Indications Pedestrian Timing Rest in Walk Mainline Pedestrian Buttons Work Pedestrian Buttons Oriented Correctly sk sura G 00071 CRISS Pedestrian Signs No Arrow Across Pedestrian Movement Stop Bar Location and Condition Channelization Lane Control Pavement Markings Auxiliary Turn Lanes Long Enough to Avoid Spillback Turning Radii Left Turn Only Sign on Mast Arm if no left turn phase Painting Galvanization ONLY Overhead Street Name Signs Mast Arms Advance Warning Signs Appropriate for the Situation TRAFFIC STUDIES MANUAL Page 66 March 9 2011 Figure 10 3 Example of a Left Turn Operational Review East West Street North South Street Analyst Date Time Period Demand but w opposing Grn Arrow No Vehicle o L cL Demand but Not Served Grn Arrow TRAFFIC STUDIES MANUAL Page 67 March 9 2011 This page Intentionally left blank TRAFFIC STUDIES MANUAL Page 68 March 9 2011 11 1 1 2 3 4 5 6 7 CHAPTER 11 CURVE ADVISORY SPEED STUDY PURPOSE The average crash rate for horizontal curves is about three times the average crash rate for highway tangents Glennon
31. TRAFFIC STUDIES MANUAL Page 35 March 9 2011 6 2 2 DEPARTURE SIGHT TRIANGLES Appropriate departure sight triangles provide adequate sight distance for a stopped driver a minor roadway to depart from the intersection and enter or cross the major roadway These sight triangles should be provided in each quadrant of a controlled intersection Departure sight triangles are illustrated in Figure 6 2 Figure 6 2 Departure Sight Triangles MEN Major street Minor Street 6 2 3 OBSTRUCTIONS WITHIN SIGHT TRIANGLES Source CTRE Minor Street 1 To determine whether an object is a sight obstruction consider both horizontal and vertical alignment of both roadways as well as the height and position of the object AASHTO Green Book For passenger vehicles it is assumed that the driver s eye height is 3 5 feet and the height of an approaching vehicle is 4 25 feet above the roadway surface as illustrated in Figure 6 3 At the decision point the driver s eye height is used for the measurement Sometimes a higher driver s eye height should be considered for drivers of trucks to see underneath the tree canopy Figure 6 3 Heights Pertaining to Sight Triangles Major Street TRAFFIC STUDIES MANUAL Minor Street u m sss s Decision Point Driver Eye Height 3 5 Source CTRE Page 36 Vehicle Height 4 25 feet March 9 2011 2
32. a speed other than the posted speed limit The Department prefers that any no passing zone be established using the range tracking system prior to any no passing zone markings being applied However emergency situations can arise that require the installation of some form of reasonable no passing zone markings before the roadway can be properly range tracked The one vehicle method may be used to establish the interim no passing zone markings in those emergency situations RANGE TRACKING Range tracking requires two vehicles equipped with drivers two way radios and the Novastar II Range Track Survey System The vehicles used shall be intermediate size The lead vehicle 1s equipped with a calibrated DMI telemetry modem to transmit its road track distance to the trailing vehicle and a target for eye height The trailing vehicle is equipped with a calibrated DMI telemetry modem to receive the lead vehicle s road track distance the range tracking computer printer and a pressurized paint canister with a spray nozzle and remote actuator The two vehicles are driven over the roadway in question at a pre determined speed and spaced at the appropriate minimum passing sight distance apart The driver of the lead vehicle maintains as steady of speed as possible so the driver of the trailing vehicle can maintain the proper separation distance A complete no passing zone study requires three passes along the roadway On the first pass whenever the ope
33. across uncontrolled roadway at this Intersection then a pedestrian gap study see Chapter 9 should be performed and the results tabulated on the Pedestrian Gap Study form Form TR 12 and the School Crossing Warrant Sheet Form TR 01a should be completed which can be found under the Wrnt 5 tab of the Traffic Signal Warrants worksheet f If Yes is selected for the question Is there a railroad grade crossing within 140 feet of the intersection on a STOP controlled approach then the Intersection Near a Grade Crossing Warrant Sheet Form TR 01b should be completed and which can be found under the Wrnt 9 Input Fig 4C 9 and Fig 4C 10 tabs of the Traffic Signal Warrants worksheet g The traffic volumes can be input manually but the recommended method is to copy the volumes directly from the PetraPro software program To prepare the count data first arrange the approaches in the order of Northbound Southbound Eastbound and Westbound using the approach wizard tool Then if all of the count intervals start on the hour 1 XX 00 change the interval length to 60 minutes using the Tools dropdown menu in PetraPro then selecting Change Interval Length and 60 minutes If any of the count intervals were started on the quarter hour 1 e XX 15 XX 30 or XX 45 the count data will need to be moved to where it starts on the hour in order for the PetraPro software to process the count data into f
34. any changes in adjacent land uses Includes a water drainage plan Proposed accesses meet Access Manual minimum spacing Existing Traffic ADTs on all affected routes Design hourly volumes on all routes intersections Atleast 4 peak hrs turning movements at all existing intersections Existing traffic control including signal phasing and coordination Includes traffic cenerated by previously approved developments Exisitng LOS and delay analysis at affected locations is reasonable site generated traffic Projected volumes at full build out If phased construction includes volumes for each phase Includes an ana ysis of build out year and years to build out Volumes are per latest ITE Trip Generation Cres pace number graph and or formula from ITE Trip Generation Generated site traffic distribution is reasonable Entering and exiting directional splits are reasonable Includes 991 percentile queue lengths at all internal contlic points Internal circulation does not cause problems for mainline traffic Projected future traffic volumes non site generated are reasonable LOS and delay analysis at affected locations 15 reasonable Includes 351 percentile queues al affected interseclioris Projected plus site generated traffic volumes are correct LOS and delay analysis at affected locations is reasonable Includes 35th percentile queues at affected intersections Mitigation Measures Clearly identifies needed improvements Includes camparison of impacts with and withou
35. as a function of intersection conditions Compute other user impacts Stops Delays e Excess Fuel Consumption Estimate cost of signal removal and costs of continuing signal maintenance Canvas strength of opposition to ancl support for signal removal Assess all factors decide whether to remove signal or not Prepare signal removal justification report Assess all factcrs decide whether to remove signal or not Obtain authorization to proceed with signal removal The steps contained in the detailed analysis are designed to allow the traffic engineer to estimate the expected impacts that will result from the removal of the traffic signal at a particular intersection Knowledge of these expected impacts forms the technical basis for the final decision to remove or not remove the signal 16 3 1 EXPECTED INFLUENCE ON CRASHES 1 2 Crash both historical and expected can be a very tough Issue when considering signal for removal thorough review of the crash history should be done to determine what has been occurring at the intersection Historically the removal of unwarranted signals and conversion to two way stop control will cause a reduction in rear end type collisions but an increase in right angle crashes might be expected The nature of the crashes that could be expected after the removal of the signal 1s influenced by the type of control that will replace the signal
36. average for similar intersections is to review past crash records for a minimum of three but preferably five years Crashes many times can also be related to the previously described problems of vehicle and pedestrian delay yet poor geometric design may be the overriding factor The following information can be used to further define a crash problem a Hourly approach volumes and pedestrian volumes from the turning movement count Chapter 4 for the highest 8 hours of an average day as required for MUTCD Warrants 1 5 and 7 9 b Crash records rates as required for MUTCD Warrant 7 c Collision diagram Chapter 7 d Speed study Chapter 13 may be required for MUTCD Warrants 1 4 and 7 e Intersection sight distances Chapter 6 f Geometrics vertical and horizontal e Pavement condition for skid resistance h Roadside hazards Existing positive guidance through signing and marking j Existing highway lighting k Traffic conflict investigation and analysis This list of data to be collected for each of the three basic areas of concern is neither all inclusive nor suggested as a minimum effort Keep in mind that data 15 required for justification warrant analysis and other data 15 required for design and operation Data for justification however is not mutually exclusive of the data required for design and operation The engineer should not attempt to collect any of the data elements listed unless he 15 certa
37. be general reasons that the signal Is being removed e g change in traffic flow patterns closing of nearby generator and a description of the benefits that will be derived by its removal reduction in delay fuel consumption and crashes To ensure that the citizens in the immediate vicinity will be notified of the proposed signal removal a letter containing the same information as the press release can be sent directly to the residents and commercial establishments within the immediate vicinity of the candidate intersection 16 5 2 INSTALL INTERIM CONTROL If the intersection will be stop controlled once the traffic signal 15 removed in order to transition the public to the removal of the traffic signals the following steps should be followed prior to the removal of the signal 1 2 3 The traffic signal should be placed in flashing operation reflecting two way yellow red or all way all red stop control as appropriate and temporary STOP signs installed on the respective approaches This operation should be maintained for a day or two typically no more than one week to make sure the intersection will not fail under the proposed stop control If after the initial flashing operation the operation and safety is acceptable the signal should be turned off and permanent post mounted STOP signs should be installed on the appropriate approaches The signal heads should be covered or turned away from traffic Signal related
38. beginning of the study Each time the vehicle slows down and crosses the Stop Speed boundary stop 15 counted The vehicle must speed up faster than the threshold before another stop can be counted A run where the user collected segment node data Most users when doing a run will collect segment node data by noting there location as they pass by the pre determined nodes in the route The distances measured for a single run are not very accurate so collecting segment node data on multiple runs and averaging the node distances from each of the primary runs in a study will result in more accurate distances between nodes A single collection of travel time data For example when data is collected along an arterial the user drives to the beginning of the arterial under study starts data collection proceeds along the arterial to the end of the study area and then stops data collection He has just completed one run If he turns around and collects data in the other direction it 15 another All runs are stored as separate entities A run where the user did not collect segment node data or A primary run in which the user decides not to use the segment node data to find the node distances for the study You do not have to collect segment node data while doing a run You may have done several runs in that direction and know you have sufficient data to find accurate node distances or you may have made several mistakes marking the node
39. comfortable operating speed However if one curve in the series has a dramatically lower comfortable speed it would be desirable to place a separate warning sign with the appropriate advisory speed for that individual curve Since warning signs are primarily for the benefit of the driver who is unfamiliar with the road it is very important that care be given to the placement of such signs Warning signs should provide adequate time for the driver to perceive identify decide and perform any necessary maneuver to safely negotiate the curve The advance distance for the placement of warning signs is determined by the posted speed limit on the section of roadway being studied Once the type of warning signs has been selected the proper sign location can be determined The advance warning sign placement shall be in accordance Table 2C 4 in the MUTCD Figure 11 4 1s an example of a data collection form that can be used to record the results of curve advisory speed studies Additional information on sign placement and establishing curve advisory speeds 15 contained in the Traffic Control Devices Handbook Chapter 4 Regulatory and Warning Signs Pages 107 110 This handbook is available through the Institute of Transportation Engineers 1099 14 Street NW Suite 300 West Washington D C 20005 3438 TRAFFIC STUDIES MANUAL Page 74 March 9 2011 11 5 1 2 3 4 5 6 7 USE OF CURVE ADVISORY SPEED STUDY FORM En
40. delay and inconvenience to traffic has failed to solve the traffic problems 3 9 WARRANT 2 FOUR HOUR VEHICULAR VOLUMES The Four Hour Vehicular Volume signal warrant is intended to be applied where the volume of intersecting traffic is the principal reason to consider installing a traffic control signal The warrant conditions are detailed in Section 4C 03 of the MUTCD 3 10 WARRANT 3 PEAK HOUR The Peak Hour signal warrant is intended for use at a location where traffic conditions are such that for a minimum of 1 hour of an average day the minor street traffic suffers undue delay when entering or crossing the major street The warrant conditions are detailed in Section 4C 04 of the MUTCD This signal warrant shall be applied only in unusual cases such as office complexes manufacturing plants industrial complexes or high occupancy vehicle facilities that attract or discharge large numbers of vehicles over a short time 3 11 WARRANT 4 PEDESTRIAN VOLUME The Pedestrian Volume signal warrant is intended where the traffic volumes on a major street are so heavy that pedestrians experience excessive delays in crossing the major street The warrant conditions are detailed in Section 4C 05 of the MUTCD 3 12 WARRANT 5 SCHOOL CROSSING The School Crossing signal warrant is intended for application where the fact that school children cross the major street 15 the principal reason to consider installing a traffic control signal The warrant co
41. experience for at least a 12 month period These other factors may be used to justify a speed limit somewhat lower than the 85th percentile speed but in no circumstance should the speed limit be posted below the 50th percentile speed or lower limit of the 10 mph pace The Speed Study output sheet compares the posted speed limit to these two factors and raises a red flag whenever the posted speed limit is posted too low RECOMMENDED SPEED LIMIT 45 POSTED SPEED IS TOO LOW In cases where the speed limit is posted below the 85th percentile speed based on the other factors the speed limit sign serves to remind motorists that conditions in the area are such that the speed reduction is reasonable Proper use of speed limit signs would instill confidence in the minds of drivers that the information on the speed limit sign 1s accurate and not simply a desire on the part of a policy maker to reduce speed arbitrarily for emotional or political reasons For additional guidance on determining appropriate speed limits a web based expert system was developed by the FHWA as part of NCHRP Project 3 67 to help determine the most appropriate speed limit for a given route This system can be found at This site requires users to establish a user name and password to access the system TRAFFIC STUDIES MANUAL Page 93 March 9 2011 13 6 DECLARATION SPEED LIMIT Posted speed limits other than statutory speed limits on state highway system that have be
42. in contact with the local governmental agency representatives local police department affected business leaders and neighborhood associations to obtain their opinions and possible opposition or support for the signal removal concept A brief summary of that opposition or support should be entered in the comments field STAGE 3 5 FINAL DECISION After thoroughly analyzing the results of the Signal Removal Analysis worksheet and the Signal Removal Impacts worksheet decide whether to retain or recommend removal of the signal and place a checkmark in the respective field A brief summary explaining the decision can be entered in the comments field TRAFFIC STUDIES MANUAL Page 126 March 9 2011 Figure 16 4 Example Signal Removal Analysis Worksheet Page 1 of 2 SIGNAL REMOVAL ANALYSIS WORKSHEET Stage 1 Intersection Inventory Intersection Major St Spruce Street Minor St 7th Street Major Street Speed 30 City Rawlins Lanes Approach 2 9 350 1 1 220 mph Side Street Sight Distance 350 east and 550 west from north leg 400 east and 420 west from south leg Stage 2 Preliminary Screening 1 Minimum Required Sight Distance from Table 16 4 Is Intersection Sight Distance Less Than Vinimum 2 Do Special Site Conditions Make Signal Removal Institutionally Infeasible Comments None that are known 3 Does Ex
43. include any remarks that may affect the data being collected PEDESTRIAN GROUP SIZE SURVEY The purpose of the pedestrian group size survey is to determine the 85th percentile group size of pedestrians that cross the street at the pedestrian gap study location Pedestrians waiting to cross a roadway will generally arrange themselves in rows one behind the other Group size is comprised of row width and number of rows When the group starts to cross they enter the roadway step off the curb with approximately 2 seconds of headway between rows Since the factor of interest 15 the amount of time it takes the entire group to enter the crossing it 15 only necessary to determine the predominant number of rows entering the crossing The width of the rows and the total number of pedestrians the group are inconsequential Distinguishing distinct rows may be somewhat difficult at first With some training and experience however observers manage easily A sample of 30 to 50 groups is usually sufficient to establish the group size 1 e number of rows per group This measurement should be made TRAFFIC STUDIES MANUAL Page 49 March 9 2011 4 5 6 9 4 1 2 3 during time and under the conditions of interest for the gap study The observer should be positioned unobtrusively perpendicular to the crossing and parallel to the roadway with a clear view of the crossing point with the heaviest concentration of pedestrians
44. installStopSigns 9150 00 52150 2 Timing Annual Stop Sign Maintenance 920 00 Total 000 0 Total 751 30 CRF Recovery Factor For 15 Years Al 12 Inleresl Annual Operation Costs Annual Removal Costs Annual Cost Savings From Signa Removal 3 4 Anticipated Strength of Opposition Support For Signal Removal Comments The general consensus seems to be that this signal is causing more problems that it is helping Objections to its removal should be minimal 3 5 Final Decision Retain Signal Ll Recommend Removal Comments Signal removal should reduce crashes and significantly improve efficiency The cost to reconstruct Spruce Street will be reduced by not having to upgrade this signal TRAFFIC STUDIES MANUAL Page 128 March 9 2011 Figure 16 5 Example of Worksheet for Estimating Daily Impacts of Signal Removal and Replacement by Two way Stops INTERSECTION TYPE 4 Way t Intersection IDLING TOTAL TOTAL 1 Main Road 2 Lane 4 Lane DELAY DELAY STOPS Side Road lana lt Lane VEH HRS VEH HRS VEH STOPS a Signal 2 PEAK HOURS E T 02 07 11 a Total Main Road Vol 700 2 b Side Road Vol Approach Total Intersection Vol lt i 1 2 2 4 TOTAL OF THE Ee x2 Signal REMAINING 22 HOURS me udin 01 03 40 O2 a Total Main Road Vol ro os 5 b Side Road Vol Approach c Total Intersection Vol iski 1 4 160 1 TOTAL THE RE x 22
45. left turn signal faces protected permissive left turn phases controlled with 4 all arrow signal faces will be lagging phases unless the adjacent through phases are coordinated with other signals on the highway corridor and leading one or both of the left turn phases improves the two way progression of traffic from one signal to the next protected permissive left turn phases controlled with 5 section left turn signal faces will be leading phases unless there 15 no opposing left turn movement e g at a T intersection or at the intersection with a one way street and the adjacent through phases are coordinated with other signals on the highway corridor and lagging the left turn phase improves the two way progression of traffic from one signal to the next PEDESTRIAN PHASES For pedestrian phases the first decision 15 whether or not to provide pedestrian indications at the intersection and which if any potential pedestrian crossings will be controlled with pedestrian indications 1 traffic signals in central business districts shall be equipped with pedestrian indications 2 Any traffic signal that was Installed based on the Pedestrian Volume warrant Warrant 4 or the School Crossing warrant Warrant 5 shall be equipped with pedestrian indications 3 Any traffic signal that 15 located on a designated school walk route shall be equipped with pedestrian indications to control the crossing of any approach leg
46. mE ER EMEN 35 6 1 JULIO td ub 35 6 2 INTERSECTION SIGITI DIST ANGE uuu k x u a t 35 6 2 APPROACH SIGHETRIANGLPEPS 35 0 242 DEPARTURE SIGHT TRIANGLE 5 n 36 6 2 3 OBSTRUCTIONS WITHIN SIGHT TRIANGLES a IS tI e et iSt 36 6 3 SIGE LT DISTANCE STUDY METHODS i i rre ennt a PERS a Rit Re 37 6 5 UNCONTROLLED INTERSECTIONS uuu A a a au u as 36 6 3 2 INTERSECTIONS CONTROLLED WITH STOP SIGNS 40 0 3 3 SSTOPPINGSIGHT DISIANCE ous mai do 41 CHAPTER 7 CRASH STUDY acces ss 43 7 1 lURP OSE uo nan n eot ote Ene rer errr er ter 43 COLLBION DIAGRAM ous amu a a 43 7 3 CRASELEIS EINGO au as a 43 CHAPTER S STOPSIGNDIEBLAYSTIUDY u a 47 8 1 PURPOSE ee EO Pt i ee 47 8 2 STOP SIGN DELAY 47 8 3 FIELD OBSERVATION CHAPTER PEDES TRIAN GAP STUDY uuu Au aa 49
47. mph 65 PAVEMENT CONDITION Dry DATE VEHICLE 2007 CHEVROLET IMPALA DRIVER Auzqui RECORDER Persson REMARKS Example Only DIRECTION REFERENCE MARKER SPEED BALL BANK READING DEGREES T iii wm we mmi ww som me mus s r7 o Mem we we x e w w Sou mus o w w we we s uw 01 _ Sou mee mus 4 089 x j x o j j LLL LLL LL uu x LLL LL LLL LLL S x LLL LLL LL x x ee ee LL LLL LL S TRAFFIC STUDIES MANUAL Page 76 March 9 2011 11 6 1 2 3 4 5 TRUCK ADVISORY SPEEDS Large trucks tank trailers and truck freight trailers have a higher center of gravity and are more susceptible to rollover crashes on a sharp curve The loop ramps on freeway interchanges and direct freeway to freeway connections are sometimes subject to truck rollover problems The potential for such crashes may increase because of the radius of horizontal curvature inadequate deceleration length or deficient specif
48. of change in average annual crash frequency resulting from the removal of a signal and installation of two way stop control X Volume magnitude as measured by the number of hours per day when the traffic volumes satisfy at least 60 of the signal installation volume warrant MUTCD Warrant 1 Condition see Table 16 1 X Average annual crash frequency at the intersection under signal control TRAFFIC STUDIES MANUAL Page 114 March 9 2011 6 7 8 Table 16 1 Volume Maenitude NUMBER OF HOURS DAY THAT INTERSECTION VOLUMES EXCEED THE FOLLOWING VOLUME LEVELS LANES APPROACH MAJOR STREET MINOR STREET BOTH APPROACHES IGRER VOLUME APPROACH ONLY MAJOR MINOR vph ed 1 1 2 1 2 2 1 2 nomograph of predicted changes in annual crash frequency for various combinations of X and X was developed using Equation 16 1 Itis shown in Figure 16 3 and may be used for estimating the expected changes in crash frequency resulting from signal removal If all way stop control is planned after removal of the signal a decrease in crashes of approximately 60 percent can generally be expected provided the intersection has the following characteristics a Low volumes less than 800 entering vehicles during the peak hour b Relatively balanced flows ratio of major street volumes minor street volumes 3 1 If a roundabout is planned after removal of the signal a reduction in overall crash frequency of approximately 3
49. or to the inside edge of the parked vehicles if no markings exist c There 15 an area provided for parking but due to minimal parking activity that area 15 typically used by vehicles as a de facto right turn lane In this case measure to the projected parallel lip of curb d There is a dedicated right turn lane Measure to the projected parallel edge line or lip of curb if no edge line Figure 10 1 is an intersection diagram that was developed to help simplify standardize the process used to measure the crosswalk length The diagram shows how to measure the crosswalk length for each of the above conditions The measurement should start in the center of the pedestrian ramp or anticipated beginning point if no ramp at the lip of curb and proceed in a counterclockwise direction to the opposite corner stopping at the point indicated above PRETIMED VERSUS ACTUATED CONTROL There are many factors that influence the decision concerning whether a traffic control signal should operate on a pretimed semi actuated or fully actuated basis Those factors include a Equipment availability b Traffic patterns c Proximity to other traffic control signals d Availability of funds Pretimed signals provide a consistent and regularly repeated sequence of signal indications to traffic while actuated signals provide at least some signal intervals that fluctuate with traffic demands The duration of some but not all phases of semi actuated sig
50. patterns eliminate the need for a traffic control signal consideration should be given to removing it and replacing it with appropriate alternative traffic control devices if any are needed The first indication that a traffic signal may no longer be justified is 1f the traffic volumes at the intersection do not meet any of the MUTCD warrants for signal installation However it is possible that a signalized intersection that does not meet any of the warrants will meet at least one warrant after the signal is removed due to increases in crashes delay or traffic patterns Therefore the removal of a traffic signal requires thorough engineering study The decision to remove an existing signal can be a difficult one There is a public perception that traffic signals are a panacea for all traffic problems at an intersection and therefore signals enjoy a high status among many segments of the public elected officials and public administrators If the removal of an existing traffic signal is to be successful this perception by the general public is the greatest hurdle to overcome Given this popular bias the practical reality 1s that signals are considerably harder to remove than to install While this can be a very high hurdle it is possible to clear if the proper engineering considerations are made and supported This chapter sets forth the procedure required to justify the removal of an existing traffic control signal The discussion and analysis
51. process 15 adapted from the Federal Highway Administration FHWA publication prepared by JHK amp Associates and Wagner McGee Associates entitled User Guide for Removal of Not Needed Traffic Signals Implementation package FHW A IP 80 12 November 1980 procedure 15 intended to provide documented support for the decision to remove an unwarranted signal to determine the appropriate alternative traffic control and to make the transition from signalized to unsignalized control as safe and efficient as possible The process consists of a series of criteria all of which must be satisfied and the various impacts predicted before signal removal 15 recommended The decision process has been built into a series of forms and nomographs to aid the traffic engineer in making the decision to remove or retain an existing Signal The use of these forms and nomographs is explained in detail at the end of this chapter see Page 121 STAGE 1 PRELIMINARY SCREENING The first step the removal process is to indentify whether or not the intersection 15 a legitimate candidate for possible signal removal There are five areas that need to be considered before seriously pursuing the removal of an existing signal sight distance special site considerations warrants crash experience and special justifications The decision to pursue the removal should only be made after these areas have been thoroughly evaluated This part of the process can be comp
52. road the observer should sight from the top of the sighting road while the assistant moves away in the direction of travel The assistant stops when the bottom 2 foot portion of the target rod is no longer visible This is the distance at which a 2 foot tall object can no longer be seen by an approaching driver The distance from the disappearing point to the observer is measured and recorded Table 6 3 Stopping Sight Distance Design Speed Stopping Sight Distance feet 115 155 0 5 0 360 425 495 570 645 730 820 910 Source AASHTO Green Book 2004 mph Q2 N C2 N NIO N N O O OI O O C2 N Figure 6 7 Heights Pertaining to Stopping Sight Distance SIG HT LINE 3 5 ft Driver Eye Height 2 ft Object Height Recommended Stopping Sight Distance Xr Source CTRE 9 The analysis of stopping sight distance consists of comparing the recommended sight distance to the measured sight distance The measured stopping sight distance should be greater than the recommended stopping distance On a horizontal curved roadway a sight obstruction may be due to the curve or to physical features outside of the roadway On straight roadway the sight obstruction will be due to the vertical curvature of the roadway TRAFFIC STUDIES MANUAL Page 42 March 9 2011 CHAPTER 7 CRASH STUDY ZI PURPOSE 1 The purpose of a Crash S
53. s that include the school walk route 4 Signalized intersections that have pedestrian facilities sidewalks and ADA ramps provided on both sides of the intersection to allow for the continuation of the pedestrian walkway should be equipped with pedestrian indications unless a pedestrian study indicates that there are less than 5 pedestrians using the crossing per hour during the peak hour of pedestrian crossing activity 5 Appropriate pedestrian phase timings and operation are outlined in Chapter VI of the WYDOT Electrical Traffic Control Manual 2006 10 7 PEDESTRIAN CROSSING DISTANCE MEASUREMENT 1 The pedestrian clearance time at all traffic signals must be sufficient to clear the pedestrian to the far side of the traveled way The measurement of the crossing distance is critical to the proper TRAFFIC STUDIES MANUAL Page 61 March 9 2011 2 10 8 1 2 3 timing of the pedestrian clearance time The crosswalk distance can vary greatly considering many variables that might be present at the intersection such as turn lanes parking lanes and corner radii There are essentially four conditions that will be encountered when measuring the crosswalk They are a There is no parking lane or right turn lane In this case measure to the projected parallel edge line or lip of curb if no edge line b There is a dedicated and well used parking lane In this case measure to the projected parallel parking or edge line
54. should use their own cost data to calculate the cost savings of signal removal If local actual costs are not available Tables 16 2 and 16 3 provide ranges of these costs which can be used to estimate the cost impacts Table 16 2 Annual Cost per intersection of continued signal operation Type of Signal Control Electrical 180 550 180 550 180 550 Maintenance 600 1600 750 3000 750 3500 Signal Timing 80 125 80 125 80 125 Annual Total Cost 860 2275 1010 3675 1010 4175 Table 16 3 Cost Impacts of signal removal Implementation Cost Equivalent Uniform Annual Cost Remove Signal Hardware 3 000 10 000 9447 1490 Install Stop Signs 120 500 18 75 Sign Maintenance 16 30 Note Analysis period is 15 years and an interest rate of 12 capital recovery factor 0 149 16 3 4 CANVAS PUBLIC OPPOSITION Assess the relative strength of opposition to or support for the proposed signal removal This is a consideration that begins here and continues even after the decision to remove a signal has been made Initially at this stage of the decision process the local governing agency representatives neighborhood and business leaders and police can be contacted for their opinions This initial canvassing provides a general idea of the opposition or support that may be expected during the interim control period and or at council meetings This item 15 pursued further duri
55. sign delay study is used to evaluate the performance of stop controlled intersections in allowing traffic to enter and pass through or to enter and turn onto another route This study will effectively provide a detailed evaluation of stopped time delay at the intersection This study is generally used in conjunction with Warrant 2 Interruption of Continuous Traffic and Warrant 3 Peak Hour Delay 8 2 1 2 3 8 3 1 2 3 STOP SIGN DELAY STUDY The stop sign delay study should be collected using an electrontc traffic data collector such as a Technologies TDC 8 or TDC 12 The stop sign delay study is designed to measure the traffic characteristics at an intersection controlled by a STOP sign Although it primarily measures delay it also provides information about the queue length and traffic volume on an approach The study procedure is detailed in the respective User s Manual for the TDC 8 or TDC 12 Figure 8 1 is an example of the stop sign delay study output with 15 minute intervals and hourly summaries A stop sign delay study should be used to measure delays during the highest peak hour of each of the three peak periods 1 e AM Noon and PM The correct hours to study can be determined by first completing a turning movement count Chapter 4 at the intersection FIELD OBSERVATION Stop sign delay studies are normally done at one approach to an intersection Typically the approach with the highest vo
56. signal offset improvements if possible to achieve smoother flow and reduce stops semi actuation or full actuation if pretimed shortening of average side street green intervals through pedestrian actuation installation of advance warning devices improved pavement friction turn prohibitions parking prohibitions improved geometric design features d If such alternatives have not been considered then their potential and relative costs should be investigated as possible alternatives to signal removal as minor and relatively inexpensive improvements to the signal might improve the safety performance of the intersection to where removal of the signal may become infeasible e If the alternative safety improvements have been considered and they would not be expected to improve the safety performance of the intersection then the signal removal process should proceed to the next stage Regardless of the traffic control that is planned after the signal is removed a detailed before after review of crashes must be done after the signals are removed and needs to be well documented This 15 because fear of an increase in crashes will be one of the most significant points of opposition to the proposal If the signal 1s to be replaced with two way stop control the following equation can be used to predict the change in the annual crash frequency resulting from signal removal Equation 16 1 Y 1 01 0 139X 0 605 Where Y Estimate
57. signing should be removed from the intersection The signal poles mast arms controller cabinet and all wiring should be left in place at this time If after approximately 3 months of STOP sign control intersection operation and safety 15 acceptable the signal heads and mast arms can be removed TRAFFIC STUDIES MANUAL Page 119 March 9 2011 4 5 After an extended typically 12 months period of acceptable sign control operation remaining signal components should be removed A comprehensive removal should be completed with all signal poles controller cabinet and wiring removed and all concrete foundations and bases removed to at least flush preferably at least 8 inches below grade in turf areas with the ground pull boxes should either be removed or filled to prevent them from collapsing in the future If the intersection will be converted to a roundabout the intersection modifications will require a significant construction project to modify the approaches and install the appropriate center island and splitter islands This work will more than likely encroach on the existing signal hardware installations Therefore the removal of the traffic signal should be coordinated with and occur during the construction project 16 5 3 MONITOR CRASHES 1 2 3 Since crashes at individual intersections cannot be predicted with complete accuracy it 1s vital to closely monitor crashes throughout the interim control peri
58. street approach with two or mora lanes and 100 vph applies as the lower threshold volume for a minor street approach with one lane TRAFFIC STUDIES MANUAL Page 24 March 9 2011 Figure 3 2 Example Traffic Signal Warrants Worksheet Page 6 of 6 am 01 Revised 8 17 10 TOTAL OF ALL PEDESTHRIANS CROSSING MAJOR STREET PEDESTRIANS PER HOUR PPH TOTAL OF ALL PEDESTRIANS CROSSING SIHEEI PEDESTRIANS PER HOUR TRAFFIC STUDIES MANUAL Page 6 of 6 Figure 4C 5 Warrant 4 Pedestrian Four Hour Volume ER L EB o 00 1000 1100 1200 1300 MAJOR STHEET TOTAL OF BOTH APPHOACHES VEHICLES PEH HOUH VPH Note 107 pph applies as the lower threshold volume Figure 4C 7 Warrant 4 Pedestrian Peak Hour 400 500 600 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 MAJOR STREET TOTAL OF BOTH APPROACHES VEHICLES PER HOUR VFR Note 133 applies as the lower threshold volume Page 25 March 9 2011 Figure 3 3 Example School Crossing Signal Warrant Sheet Form 01 Revised 3017 10 Page 1 of 1 WYOMING DEPARTMENT OF TRANSPORTATION TRAFFIC SIGNAL WARRANTS SCHOOL CROSSING SIGNAL WARRANT SHEET Dubois 5 Fremont 4 31 10 City Dist County Observer Study Date Major Street Main Street Minor Street D Street Start Time 3 30PM End Time 4 30 PM Duration 60 minutes Width of Major Street W 60 ft Minimum Acceptable Gap to Cross G 20 1
59. the clear storage distance as required for MUTCD Warrant 9 MUTCD Section 4C 10 e Travel time and delay study Chapter 14 PEDESTRIAN A pedestrian problem can also be diagnosed through field observation However the severity of this problem is difficult to ascertain without field data collection The types of data which may be needed for this investigation are summarized below a Turning movement count Chapter 4 that includes hourly approach volumes for the highest 8 hours of an average day as required for MUTCD Warrants 1 2 3 and 8 and pedestrian volumes as required for MUTCD Warrants 4 and 5 b Pedestrian gap study Chapter 9 as required for MUTCD Warrants 4 and 5 c Verification from the condition diagram Chapter 5 that the distance to nearest crosswalk or signalized intersection is greater than 300 feet as required for MUTCD Warrants 4 and 5 d Characteristics of pedestrians such as age disability average walking speed etc TRAFFIC STUDIES MANUAL Page 4 March 9 2011 2 4 5 CRASHES 1 2 3 4 2 5 The determination of an intersection s crash potential during a short field observation 15 difficult Some obvious features of a high crash location may be damaged sign supports or excessive tire skid marks however the number of crashes 1s not normally shown by the previous features The quickest and cheapest method of determining if crashes are a problem e g significantly higher than
60. the distance to the next traffic signal in each direction 1f applicable Figure 5 1 gives an example of a completed condition diagram TRAFFIC STUDIES MANUAL Page 33 March 9 2011 Figure 5 1 Example Condition Diagram O Y d L 4 9 Herder gt N 1 d 3 x 2 ie i 3 N N EE JE N 24 I Lst N f 988 N Y Ri 552 888 UK SIGN patalla b 4 Light Grass 1 iz 4 14 Light Stops Q TA SS be Qj MERCEDE ET 4 407 4 T 77 s eR gt O sesin 5 5 R ba TRAFFIC STUDIES MANUAL Page 34 March 9 2011 CHAPTER 6 SIGHT DISTANCE STUDIES 6 1 PURPOSE 1 Sight distance is the length of roadway visible to a driver The three types of sight distance common in roadway design are intersection sight distance stopping sight distance and passing sight distance This chapter will discuss intersection sight distance and stopping sight distance Information on passing sight distance can be found in Chapter 12 of this manual and in Chapter 3 of the AASHTO A Policy on Geometric Design of Highways and Streets Green Book 2 A sight distance study at an intersection includes four key steps Determine minimum recommended sight distance Obtain or construct sighting and target rods Measure current sight d
61. the engineer These concepts should then be screened based on any known constraints such as funding future programmed construction etc of the alternatives determined to be feasible by the engineer should then be evaluated using the optimization and simulation computer programs The first step 1s an isolated intersection analysis Synchro is a valuable program with a Highway Capacity Manual interface that can be used for design analysis and evaluation of isolated intersections By specifying appropriate commands and parameters this program can select optimal phase patterns and timings cycle lengths and splits Each alternative can be analyzed by the measures of effectiveness included in the output reports Several alternatives can also be evaluated by comparative analysis to determine the best alternative The Engineer of Record should be responsible for any model result a When modeling intersections using Synchro or HCS it is imperative that the factors used in the analysis reflect actual Wyoming driving conditions For example the default saturation flow rate should be set to 1600 vehicles per lane per hour of green Field observation of the traffic characteristics may be used to justify increasing the saturation flow rate to 1700 where conditions indicate that driver behavior at the intersection 15 more aggressive than the typical Wyoming intersection b With the majority of intersections in Wyoming being located in relatively sp
62. the engineering study used the satisfaction of Warrant 8 to justify the signal a traffic control signal installed under projected conditions should have an engineering study done within 1 year of putting the signal into stop and go operation to determine if the signal 16 justified If not justified the signal should be taken out of stop and go operation or removed There may be special situations where an existing signal meets one or more of the MUTCD warrants but its location spacing from adjacent signals 1s detrimental to the smooth progressive flow of traffic on the major street and the reason for considering its removal is to facilitate a new or relocated traffic signal at a location that provides more acceptable signal spacing In such a situation emphasis should be given to providing traffic that would normally use the existing signal convenient access to the new or relocated signal via nearby parallel streets or construction of new street connections This can dispel most of the concern associated with the side street traffic needing a traffic signal to gain safe and convenient access to the major street 16 2 4 SPECIAL JUSTIFICATIONS 1 2 16 3 1 2 3 There have been reasons other than the standard warrants that have been used to justify traffic signal installations There are undoubtedly cases where unwarranted signals have been installed as a result of pressure from a small special interest group based on reasons
63. total amount of time available t for pedestrians to cross the roadway Pedestrian Delay can be calculated using the following equation Equation 9 2 T t x 100 i Where Delay expressed delayed Total time of study seconds Duration x 60 Totaltime of all Adequate Gaps In seconds D T t The average number of adequate gaps per five minute period is used in determining the possible need for various pedestrian and school crossing traffic controls It can be calculated using the following equation Equation 9 3 A Duration 5 Where Number of Adequate Gaps per 5 minute period Duration Total time of study in minutes Figure 9 1gives an example of a completed pedestrian gap study form showing the completed available gap survey with the total adequate gaps percent pedestrian delay and average number of gaps per 5 minute period TRAFFIC STUDIES MANUAL Page 57 March 9 2011 This page Intentionally left blank TRAFFIC STUDIES MANUAL Page 58 March 9 2011 CHAPTER 10 SIGNAL OPERATIONS STUDIES 10 1 PURPOSE Once an engineering study has been performed and the installation of a traffic control signal has been determined to be justified many decisions must be made for its proper design and operation The proper design and operation of a traffic control signal is crucial to the safety and efficiency of the intersection once it 1s installed The operational parameters of the sign
64. using easily determined landmarks to separate the segments For arterials the segment boundaries will typically be signalized intersections but the segments may be defined any way you want TRAFFIC STUDIES MANUAL Page 97 March 9 2011 Normal Speed Number of Stops Primary Run Run Secondary Run Study The boundary between two segments of a run Every run has a starting node which Is where you start collecting data on a fixed route study an ending node which 15 where you stop collecting data and several segment nodes in between If intersections are used to define the nodes the landmark used to define the node should be at a point exiting the intersection a good rule of thumb is the far right traffic signal pole This will ensure that any delay associated with stops at the intersection will be reported in the correct section Ideal speed at which the traffic should travel on an arterial The Normal Speed is used to find Total Delay statistics for runs and studies see Total Delay below and is plotted on the Time Space Diagrams to show perfect progression This is set at the beginning of the study and is usually the posted speed limit on the corridor A stop is defined as a one second interval where the speed is less than X mph for one second when the speed was greater than X mph in the previous second X is normally 5 mph but can be set to any speed you want This speed is called the Stop Speed and is set at the
65. 1 0 1 0 1 0 1 0 1 0 03 00 PM 85 7 7 7 5 4 3 6 0 2 3 1 1 0 2 2 50 8 9 03 15 PM 92 9 11 6 7 11 2 3 3 3 1 2 0 1 1 2 62 8 9 03 30 PM 123 13 14 10 9 5 1 3 3 1 1 0 1 1 0 3 65 6 7 03 45 104 6 10 6 0 6 5 5 1 1 1 2 2 1 2 3 51 10 11 Total 404 35 42 29 21 26 11 17 7 7 6 5 4 3 5 10 228 8 9 Grand Total 404 35 42 29 21 26 11 17 7 6 5 4 3 5 10 228 8 9 Total 15 4 18 4 12 7 9 2 11 4 4 8 7 5 3 1 3 1 2 6 2 2 1 8 1 3 2 2 4 4 Direction SB 4th St Start Time Volume 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 229 Int Total Average Factor 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 03 00 PM 73 1 7 9 6 5 0 3 2 0 2 0 1 0 1 7 44 8 9 03 15 67 1 7 4 10 3 4 2 5 4 2 0 1 0 2 3 48 10 11 03 30 103 2 11 7 6 3 8 4 3 2 3 0 2 0 0 2 53 10 11 03 45 78 3 6 7 5 3 6 5 3 1 1 2 0 1 1 5 49 12 13 Total 321 7 31 27 27 14 18 14 13 7 8 2 4 1 4 17 194 10 11 Grand Total 321 7 31 27 27 14 18 14 13 7 8 2 4 1 4 17 194 10 11 Total 3 6 16 0 13 9 13 9 7 2 9 3 7 2 6 7 3 6 4 1 1 0 2 1 0 5 2 1 8 8 Direction Combined Start Time Volume 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 229 Int Total Average Factor 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 03 00 PM 158 11 11 11 11 6 4 2 1
66. 44 104 17 0 50 98 24 0 11 24 35 0 6 15 24 1 453 Total 71 182 29 0 101 189 31 0 26 58 56 0 22 44 50 3 862 04 00 29 109 10 0 72 140 14 0 17 57 17 1 22 43 50 0 581 04 15 40 79 11 0 59 92 17 3 15 41 25 3 25 35 46 0 491 04 30 52 91 5 0 49 97 18 2 19 53 25 4 21 49 45 0 530 04 45 44 108 8 0 62 89 21 0 17 41 19 1 21 39 43 0 513 Total 165 387 34 0 242 418 70 5 68 192 86 9 89 166 184 0 2115 05 00 58 131 11 0 54 93 15 0 26 66 22 0 28 63 52 0 619 05 15 48 109 15 0 42 85 12 0 14 58 21 2 18 39 42 0 505 683 1960 261 3 1077 1981 312 8 350 1087 532 18 387 832 867 111 10369 Apprch 23 5 67 4 9 0 1 310 58 6 9 2 02 176 547 26 8 09 185 397 41 3 0 5 Total 66 18 9 2 5 0 10 4 19 1 3 0 1 34 10 5 5 1 0 2 3 7 8 8 4 0 1 5 1 1 2 5 2 1 2 3 4 5 CHAPTER 5 CONDITION DIAGRAM PURPOSE The purpose of the condition diagram 15 to show the intersection and the conditions within surrounding area as it exists The diagram should include the intersection alignment items such as buildings sidewalks trees light poles fire hydrants stop signs number of lanes lane use if required approach speed limits and distance to the next signal in each direction if applicable associated with the streets forming the intersection The condition diagram should show the length of all exclusive lanes and associated tapers The condition diagram provides the engineer with details of field conditions and he
67. 5 percent and an approximately 75 percent reduction in injury and fatality crashes can be expected 16 3 2 EXPECTED TRAFFIC FLOW RELATED IMPACTS 1 2 3 4 Traffic signal removal results in substantial impacts on intersection delays stops and resulting excess fuel consumption Replacing an unjustified signal with two way stop control at a four legged intersection has the following estimated effects a Total delay 15 reduced by about 10 seconds per vehicle b Idling delay is reduced by about 5 to 6 seconds per vehicle c Stops are reduced from about 50 percent of the total to about 20 to 25 percent or even less if side road volumes are low in relation to total intersection volume d Excess fuel consumption due to intersection stops and delays 15 reduced by about 0 002 gallons per vehicle In the case of similar volumes at a T intersection the reductions in delays stops and fuel consumption would be slightly greater Replacing an unjustified signal with all way stop control at four legged intersections has the following estimated effects a Total delay per vehicle does not change by much b Idling delay is reduced by about 5 seconds per vehicle c Stops always equal 100 percent of total traffic approximately double that experienced under signal control d Excess fuel consumption is increased by about 0 0015 gallons per vehicle TRAFFIC STUDIES MANUAL Page 115 March 9 2011 Figure 16 3 Pr
68. 62 Jos PERETINED CONTROL uuu usut h 64 05922 SPNIEACTUASTEDCONIKR01LE 64 1053 FULLY ACTUA TED CONTROL kusha 64 109 ISOLATED VERSUS SYSTEM OPERA TION uu a ono ort tesi 64 adu nis 64 FOTIL inet ve ree Gives dae as eee ae 65 LONI SIGNALIZED INTERSECTION CHECKLIST u u ess 65 IO TT 2 LEFT TURN PHASE OPERATIONAL REVIEW eee 65 CHAPTER TI S CURVEADVNVISORYSPEBDSIUDY uu Neh 69 PURPOSE aa e Sa ya ma M 69 LL2 THE DESIGN SPEED EQUATION u u uu uay uu uu nsn u aku 70 153 BAL LL BANKINDICATOR METHOD a iue 71 ESTABLISHINGCURVEADVISORYSPEBDSu 74 Lio USP OP CURVE ADVISORY SPEED STUDY FORM Q 75 We SERUCK ADVISORY SPEED uuu u aun de ditur po iSo 77 CHAPTER ID NO PASSING ZONE SID uuu S u awe u a kaa SD k Od nS Uns 79 Jl PURPOSE 2 E 79 122 JINO PASSIN
69. 7 200920230 201000621 201006562 STREET 1 ML302B ML302B ML330B ML302B ML302B ML302B ML302B ML1704B ML1704B ML302B ML302B ML302B ML302B ML330B ML302B ML302B ML302B ML302B ML302B ML330B ML302B ML330B ML302B ML302B ML302B ML330B ML6OB ML60B ML60B ML1704B ML330B ML330B ML1702B ML60B ML60B ML330B ML60B ML60B DATE 03 04 2006 05 31 2006 06 01 2006 06 02 2006 06 22 2006 07 08 2006 07 23 2006 07 26 2006 08 15 2006 09 06 2006 10 09 2006 11 22 2006 01 21 2007 03 18 2007 04 26 2007 04 29 2007 05 01 2007 07 26 2007 08 20 2007 09 23 2007 09 25 2007 10 12 2007 11 13 2007 12 01 2007 12 13 2007 01 08 2008 01 28 2008 07 27 2008 07 09 2009 07 10 2009 07 13 2009 08 14 2009 09 12 2009 09 15 2009 10 30 2009 12 06 2009 01 06 2010 05 28 2010 02 15 2011 TIME 11 00 15 00 17 00 15 0 12 00 9 00 12 0 18 00 12 00 13 00 8 00 21 00 25 00 11 0 23 00 15 00 17 00 17 00 18 00 21 00 16 00 13 00 15 00 16 00 8 00 16 00 16 00 12 00 16 00 8 00 15 0 11 00 12 00 11 00 8 00 11 00 14 00 10 00 TRAFFIC STUDIES MANUAL Figure 7 2 Example Intersection Magic Crash List DAY Sat We Thu Fri Thu Sat sun We Tue We Mon We Sun sun Thu Sun Tue Thu Mon sun TUE Fri Tue sat Thu Tue Mon sun Thu Fri Mon Fri Sat Tue Fri sun Fri INJ FAT No No No No NO
70. A GRADE CROSSING The Intersection Near a Grade Crossing signal warrant 15 intended for use at a location where none of the conditions described in the other eight traffic signal warrants are met but the proximity to the intersection of a grade crossing on an intersection approach controlled by a STOP or YIELD sign is the principal reason to consider installing a traffic control signal The warrant conditions for this warrant are detailed in Section 4C 10 of the MUTCD TRAFFIC STUDIES MANUAL Page 29 March 9 2011 This page Intentionally left blank TRAFFIC STUDIES MANUAL Page 30 March 9 2011 4 1 CHAPTER 4 TURNING MOVEMENT COUNT PURPOSE The purpose of a turning movement count TCM is to summarize the counts of vehicle movements through an intersection during certain time periods This type of volume summary is used in making decisions regarding the geometric design of the roadway sign and signal installation signal timing pavement marking traffic circulation patterns capacity analysis parking and loading zones and vehicle classification 42 MANUAL TURNING MOVEMENT COUNT 1 Manual turning movement counts should be collected using an electronic count board such as a JAMAR Technologies 400 TDC 8 or TDC 12 traffic data collector and processed through JAMAR s PetraPro software 2 The count header on the turning movement count should be filled in completely Enter the Street Name of each roadway and orient the intersec
71. AFFIC STUDIES MANUAL Page 91 March 9 2011 TR 10 MILES PER HOUR Figure 13 5 Example of Cleaned Speed Study Data Collection Sheet SPEED STUDY DATA COLLECTION SHEET Revised 3 411 Wyoming Department of Transportation CITY Ranchester ROUTE US 14 Dayton St POSTED SPEED 40 DIRECTION OF TRAVEL OBSERVER DATE TIME WEATHER Eastbound J D T 5 19 10 TO 9 50 AM Clear amp Warm 8 40 AM 20 qp o AIETE 40 AAA I AAA a Pet 55 SB EE ME ES SS ES s H 60 Ba EE SE SE EE El TRAFFIC STUDIES MANUAL MILES PER HOUR Page 92 COUNTY LOCATION COMMENTS Sheridan At 4th Ave W Example Only DIRECTION OF TRAVEL OBSERVER DATE TIME WEATHER 20 Westbound J D T 5119110 TO 10 45 AM Clear amp Warm 9 55 AM ET LAL L L L j L l I _ j j l 45 BE B SOA
72. Any object within the sight triangle that would obstruct the driver s view of an approaching vehicle 4 25 feet in height should be removed or modified or appropriate traffic control devices should be installed as per the MUTCD Obstructions within sight triangles could be buildings parked vehicles hedges trees bushes tall crops walls fences etc Figure 6 4 shows a clear sight triangle and an obstructed sight triangle Figure 6 4 Clear Versus Obstructed Sight Triangles Clear Sight Triangle Obstructed Sight Triangle i xl d 4 e l EI 1 Minor Street Source CTRE 6 3 SIGHT DISTANCE STUDY METHODS 1 Different types of traffic control require different sight distances For example intersections with no control require adequate distance for the approaching vehicle to identify any conflicts in approaching the intersection before entering An approach sight triangle is used for this analysis However intersections with stop control require drivers to stop at the intersection check for approaching vehicles in the intersection and then depart A departure sight triangle 15 used for this analysis 2 Example sighting and target rods are illustrated in Figure 6 5 The target rod can be constructed out of normal 1x2 dimensional lumber The target rod should be 4 25 feet tall to represent the vehicle height and be painted fluorescent orange on both the top portion and bottom 2 feet of the rod The bo
73. CRASH FREQUENCY Yes No ji MINIMUM REQUIREMENT NUMBER OF CRASHES 5 OR MORE CRASHES IN 12 MONTHS 3 in 2007 1 in 2008 4 in 2009 No X ONE WARRANT WARRANT 1 MINIMUM VEHICULAR VOLUME Yes Nol x SATISFIED AT WARRANT 1B INTERRUPTION OF CONTINUOUS TRAFFIC Yes X 8056 WARRANT 4 PEDESTRIAN VOLUME Yes X WARRANT 8 Roadway Network SATISFIED YES NO X MINIMUM REQUIREMENT Total entering volume equals 1000 vehicles or more per hr FULFILLED A DURING TYPICAL WEEKDAY PEAK HOUR 1834 VEH HOUR HAS S YEAR PROJECTED VOLUMES BASED AN ENGINEERING STUDY THAT MEET ONE OR MORE OF WARRANTS 1 2 AND 3 DURING AN AVERAGE WEEKDAY B DURING EACH OF ANY 5 HRS OF SATURDAY OR SUNDAY EXCEED 1 000 VEH HOUR CHARACTERISTICS OF MAJOR ROUTES IT IS PART OF THE STREET OR HIGHWAY SYSTEM THAT SERVES AS THE PRINCIPAL ROADWAY NETWORK FOR THROUGH TRAFFIC FLOW B IT INCLUDES RURAL OR SUBURBAN HIGHWAYS OUTSIDE ENTERING OR TRAVERSING A CITY C IT APPEARS AS MAJOR ROUTE AN OFFICIAL PLAN SUCH AS MAJOR STREET PLAN IN AN URBAN AREA TRAFFIC AND TRANSPORTATION STUDY ANY MAJOR ROUTE CHARACTERISTICS MET FOR BOTH STREETS Yes Mo WARRANT 9 Intersection Near a Grade Crossing Not Applicable See Intersection Near a Grade Crossing Warrant Sheet TRAFFIC STUDIES MANUAL Page 22 March 9 2011 Figure 3 2 Example Traffic Signal Warrants Worksheet Page 4 of 6 Farm TR D1 Revised 9717710
74. DATA ANALYSIS AND INTERPRETATION Once the appropriate data for the warrant analysis has been collected it is the traffic engineer s responsibility to analyze and interpret it Application of the Traffic Signal Warrants worksheet can be made in a straightforward manner and provides the traffic engineer with information concerning the minimum conditions for justifying signal installation Instructions for use of the Traffic Signal Warrants worksheet Form TR 01 are included In Chapter 3 Further explanation of the individual warrants can be found in Part 4 of the MUTCD Engineering judgment plays an important role in the decision to signalize an intersection The traffic engineers need a thorough knowledge and understanding of any local conditions which may or may not support the need for signalization Situations may arise when a traffic signal is best not installed even though one of the eight warrants may be met Such a condition may exist when minimum traffic volumes are present at a location but signalization would severely interrupt mainline movement to serve a relatively small side street movement Some additional considerations should be made by the engineer when minimum warrants have been met to insure that installation of a signal does not create a greater problem These considerations include but are not limited to the following a Development of excessive queues on the major street b Queue dissipation rates c Spacing between
75. Date Constant Nodes Start End 1 16 2 17 3 18 4 19 5 20 6 21 7 22 8 23 9 24 10 25 26 12 27 13 28 14 29 15 30 Runs Time___ Comments Time Comments 1 2 3 4 5 6 7 8 9 10 11 12 19 14 15 16 17 18 19 20 TRAFFIC STUDIES MANUAL Page 103 March 9 2011 This page Intentionally left blank TRAFFIC STUDIES MANUAL Page 104 March 9 2011 CHAPTER 15 HIGHWAY LIGHTING STUDIES 15 1 PURPOSE 1 The investment of public funds in roadway lighting returns benefits to the public in several ways Lighting benefits motorists by improving their ability to see roadway geometry and other vehicles at extended distances ahead This results greater driver confidence and improved safety particularly in inclement weather Lighting may also improve roadway capacity Other benefits include improved pedestrian safety improved public safety and security convenience and civic pride and recognition 2 WYDOT Operating Policy 25 1 Traffic Control and Roadway Lighting Devices establishes much of the criteria by which lighting will be installed at many intersections on the state highway system It lists rural and urban interstate highways including interchanges ramp termini and crossroads within the interstate right of way meeting the interchange lighting criteria of the traffic program It also lists rural locations on other state highway intersections meeting the intersection lighting criteria of the Traffic Pro
76. E 6 2 7 PREPARATION AND APPROVAL OF STUDY REPORT 6 2 8 DEVELOPMENT OF NEW TRAFFIC SIGNAL DESIGN Lu u u l L 7 2 9 TRAFFIC SIGNAL RECONNAISSANCE REPORT 9 2A IMPLEMENTATION w SS0 n04X M 9 CHAPTER 3 TRAFFIC SIGNAL WARRANT ANALYSIS 11 3 1 PURPOSE 11 3 2 TRAFFIC SIGNAL WARRANT ANALYSI S 11 3 3 APPLICATION OF REDUCED 70 WARRANT 12 3 4 APPROACILLANES quieras eut besote ants qula ume mui eic 12 3 5 D 13 3 6 FPRERIMINARI SCREENING ihe veut insect emit edunt Et veu 14 3 7 TRAFFIC SIGNAL WARRANTS WORKSHEETL 15 3 8 WARRANT 1 EIGHT HOUR VEHICULAR VOLUME 28 3 0 WARRANT 2 FOUR HOUR VEHICULAR VOLUME S 28 S10 WARRANT OG PEAK HOUR uuu
77. E PER APPROACH VPH TRAFFIC STUDIES MANUAL Page 144 TOTAL IHTERSECTION FUEL CONSUNPTION GAL PER FR TOTAL INTERSECTION EXCESS FUEL CONSUMPTION LEGEND x st BN EE AO 7 oe wp 48 r 3 SIDE ROAD VOLUME PER APPROACH WPH March 9 2011 CHAPTER 17 PREEMPTION This chapter is under development TRAFFIC STUDIES MANUAL Page 145 March 9 2011 This page Intentionally left blank TRAFFIC STUDIES MANUAL Page 146 March 9 2011 18 1 1 2 18 2 1 2 18 AUXILIARY LANE AND TRAFFIC IMPACT STUDIES PURPOSE In addition to the spacing of accesses the number of traffic lanes at intersections and accesses and the configuration of those lanes for use by left through and right turning traffic play a vital role in the overall safety and operation of the transportation system Dedicated left and right turn lanes are helpful in promoting safety and improved traffic flow in situations where traffic volumes and speeds are relatively high and conflicts are likely to develop between through and turning traffic at public road intersections and driveways On rural two lane highways the addition of truck climbing lanes and or passing lanes can enhance the safety and efficiency of the highway by increasing opportunities to pass slower moving traffic The AASHTO Green Book contains most of the criteria necessary to justify and design auxiliary lanes Thi
78. FEED Eastbound Wesibound E b mih Ch S Ca CO Fa a 4 m cn J Es Ch cn a j n Cb ic TRAFFIC STUDIES MANUAL Page 90 March 9 2011 Figure 13 4 Example Speed Study Worksheet Output SPEED STUDY E Wyoming Department of Transportation CITY Ranchester COUNTY Sheridan ROUTE US 14 Dayton St SPEED LIMIT 40 MPH DIRECTION Eastbound LOCATION At 4th Ave W OBSERVER JD T START TIME 8 40AM WEATHER Clear amp Warm DATE 5 19 10 END TIME 9 50 AM COMMENTS Example Only ACUM SPEED FREQUENCY TOTAL ACUM FPE S yU SIPIN 20 0 9 0 21 0 0 00 22 0 0 00 23 0 0 00 24 0 0 00 25 0 0 00 26 0 0 00 27 0 0 00 28 0 0 00 29 0 0 00 30 0 0 00 31 1 I 10 32 0 I 10 33 2 20 34 3 30 35 2 5 50 36 4 9 90 37 6 15 15 0 38 5 20 200 39 7 27 270 40 9 36 360 41 17 53 550 42 16 69 690 43 13 82 820 44 6 88 880 45 3 91 910 46 4 95 950 47 1 06 960 48 0 906 960 49 2 98 980 50 99 990 51 0 99 990 52 1 100 100 0 53 0 100 1000 54 0 100 1000 55 0 100 1000 56 0 100 1000 57 0 100 1000 58 0 100 1000 59 0 100 1000 60 0 100 100 AVERAGE SPEED 41 2 PACE SPEED 36 to 45 STANDARD DEVIATION 3 48 50th PERCENTILE 41 VEHICLES IN PACE 86 EXCEEDING POSTED LIMIT 64 67th PERCENTILE 42 IN PACE 86 85th PERCENTILE 44 BELOW PACE 5 RECOMMENDED SPEED LIMIT 45 95th PERCENTILE 46 ABOVE PACE 9 TR
79. G u l NUN EMEN NU MEE UEM PD IUE ee 79 1259 ZONES estes toa 90 124 RANGE TRACKING ede s Ed 81 129 ONE VEHICLE METHOD sin act AO O eiu Ia da Da 62 CHAPTER JS SPEEDSTUDHIES uu unu a See epee eu 85 OI M 85 15 2 SPEED STUDY DATACOLCECTON uuu ol total todo utei cn 85 155 SPEED STUDY DATA COLLECTION SIE ED uu ul Sumu Su 60 1345 SPFEED STUDY WORKSHEE iine d ecu 69 135 DETERMINATION OF APPROPRIATE SPEED LIMIT 93 1306 GDECEARATIONOPSPEED LIM ani utes 94 15 5 MINIMUM SPEED LIMTE S i cde usos ausu yu odo toss toes 94 TRAFFIC STUDIES MANUAL Page March 9 2011 CHAPTER 14 TRAVEL TIME AND DELAY STUDY iiir nl q q a 97 Pan E 97 1522 DERINT THON RR 97 SIDDY PROCEDURES m RENE Ei o AU 99 t44 COLLECTING THE DA m 101
80. HAPTER 14 TRAVEL TIME AND DELAY STUDY PURPOSE The purpose of a travel time and delay study is to evaluate the quality of traffic movement along a route and determine the locations types and extent of traffic delays by using a moving test vehicle This type of study can be used to compare operational conditions before and after roadway or intersection improvements have been made or signal coordination has been implemented or modified It can also be used as a tool to assist in prioritizing projects by comparing the magnitude of the operational deficiencies such as delays and stops for each project under consideration The travel time and delay study can also be used for the following purposes a By planners to monitor level of service for local government comprehensive plans b Determination of route operational efficiency or delay c Identification of congested locations such as driveways entrances etc where a significant number of turning movements occur d Evaluation of the effectiveness of traffic engineering improvements using before and after studies on projects such as signal retiming or the addition of turn lanes e Determination of level of service from average travel speed data The methodology presented herein provides the engineer with quantitative information with which he can develop recommendations for improvements such as traffic signal retiming safety improvements turn lane additions and channelizati
81. IGURE MINOR NUMBERS INTERSECTION TYPE MAJOR ROAD IDLING amp ROAD TOTAL DELAY STOPS amp FUEL 4 WAY INTERSECTION 4 2 MAJOR ROAD 16 9 16 10 2 LANE MINOR ROAD T INTERSECTION 2 LANE MAJOR ROAD 16 11 16 12 2 LANE MINOR ROAD 4 WAY INTERSECTION 4 LANE MAJOR ROAD 16 13 16 14 2 LANE MINOR ROAD 4 16 15 16 16 2 MINOR ROAD 4 WAY INTERSECTION 4 LANE MAJOR ROAD 16 17 16 18 4 T INTERSECTION 4 LANE MAJOR ROAD 16 19 16 20 4 LANE MINOR ROAD TRAFFIC STUDIES MANUAL Page 132 March 9 2011 INTERSECTION TOTAL IDLING DELAY VEH 5 PER HR Figure 16 9 Idling and Total Delay Four way Intersection Two lane Major Two lane Minor INTERSECTION TOTAL IDLING DELAY LEGEND SIGNAL 1 ae an Y LER ao SIDE ROAD VOLUME PER APPROACH TRAFFIC STUDIES MANUAL INTERSECTION TOTAL DELAY VEH HRS PER HR Page 133 INTERSECTION TOTAL DELAY LEGEND SIGNAL TWO WAY STOP w s ad 4 7 2 P P s T oM 2A 0 100 150 200 250 300 SIDE ROAD VOLUME PER APPROACH VPH March 9 2011 Figure 16 10 Stops and Excess Fuel Consumption Four way Intersection Two lane Major Two lane Minor INTERSECTION TOTAL STOPS 900 LEGEND SIGNAL 800
82. IL 4 Complete interchange lighting may be warranted where the ratio of night to day crash rate within the interchange area is at least 1 5 times the statewide average for all unlighted similar sections and a study indicates that lighting may be expected to result in a significant reduction in the night crash rate 15 2 3 PARTIAL INTERCHANGE LIGHTING Case PIL 1 Partial interchange lighting is considered to be warranted where the total current ADT ramp traffic entering and leaving the freeway within the interchange areas exceeds 5 000 for urban conditions 3 000 for suburban conditions or 1 000 for rural conditions Case PIL 2 Partial interchange lighting is considered to be warranted where the current ADT on the freeway through traffic lanes exceeds 25 000 for urban conditions 20 000 for suburban conditions or 10 000 for rural conditions Case PIL 3 Partial interchange lighting is considered to be warranted where the ratio of night to day crash rate within the interchange area is at least 1 25 or higher than the statewide average for all unlighted similar sections and a study indicates that lighting may be expected to result in a significant reduction in the night crash rate TRAFFIC STUDIES MANUAL Page 106 March 9 2011 15 2 4 NON FREEWAY LIGHTING The AASHTO Guide also contains guidelines on special considerations for roadway lighting The AASHTO Guide gives no specific warrants for continuous lighting of roadways other than freeway
83. J 2 SIDE ROAD VOLUME PER APPROACH VPH March 9 2011 Figure 16 18 Stops and Excess Fuel Consumption Four way Intersection Four lane Major Four lane Minor TOTAL INTERSECTION INTERSECTION TOTAL STOPS EXCESS FUEL CONSUMPTION T TWO WAY STOP FA F s a LEGEND TNO WAY STOP CCC er E A ES A a 4 IN ERS EC HOUR TOTAL INTERSECTION FUEL CONSUMPTION GAL PER HR 100 150 200 250 300 0 100 150 200 250 300 SIDE ROAD VOLUME PER APPROACH VPH SIDE ROAD VOLUME PER APPROACH VPH TRAFFIC STUDIES MANUAL Page 142 March 9 2011 Figure 16 19 Idling and Total Delay T Intersection Four lane Major Four lane Minor INTERSECTION TOTAL IDLING DELAY INTERSECTION TOTAL LEGEND LEGEND SIGNAL L TWO WAY STOP LL x _ INTERSECTION TOTAL IDLING DELAY HRS PER HR INTERSECTION TOTAL DELAY HRS PER HR SIDE ROAD VOLUME PER APPROACH SIDE ROAD VOLUME PER APPROACH VPH TRAFFIC STUDIES MANUAL Page 143 March 9 2011 INTERSECTICN TOTAL STOPS STOPS PER HOUR Figure 16 20 Stops and Excess Fuel Consumption T Intersection Four lane Major Four lane Minor INTERSECTION TOTAL STOPS 300 LEGEND i E z om lt Pa SS llle 70 40 30 20 100 150 200 2540 300 SIDE ROAD VOLUM
84. M 3 30 DURATION 60 MIN NUMBER GAPS MULTIPLY BY GAP seconds TALLY TOTAL GAP SIZE COMPUTATIONS edestrian Delay D Duration x 60 60 x 60 3600 sec T 10 11 12 13 14 15 16 17 18 HHI 19 20 H I 21 ME HI HHI INI H ess than 21 sec 462 D T t x 100 110 T D 3600 1590 x100 3600 n 2 3 3 EE n Ped Delay2 56 9 B3 Average No of Adequate Gaps Five min Period P A bo m Duration 5 Go 63 60 5 jeje cn E N n3 GO Gol Gol on e 4 5 Adequate gaps 5 min period un c3 A FA o n3 Ol m w 63 1590 TRAFFIC STUDIES MANUAL Page 51 March 9 2011 9 5 1 2 9 5 1 1 2 3 4 MEASURING GAP SIZES The next part of the field study 15 to measure the time leneths of eaps in traffic Gap studies can be broken into two types of studies multi direction gap studies or total combined direction gap studies Multi direction gap studies see Section 9 5 1 measure the gaps in each direction as well as the distribution of gaps across both directions Typically this is used at an unsignalized intersection or mid block crossing location to determine if the addition of a raised med
85. Maneuvers feet Source AASHTO Green Book 2004 To measure the intersection sight distance first determine the minimum sight distance for each maneuver and speed see Table 6 2 The observer records the date and time posted or operating speed site location and weather conditions on the sight distance diagram The sight distance should be measured in each direction from each minor street approach The line of sight should be from the driver s eye position where traffic would normally be expected to stop and look for gaps in approaching traffic a typical rule of thumb 15 15 feet from the near edge TRAFFIC STUDIES MANUAL Page 40 March 9 2011 9 10 6 3 3 1 2 3 4 5 6 7 of the major street traveled way Observation of traffic behavior at the intersection should be used to determine the point at which the majority of drivers stop to look for gaps in traffic without encroaching on the through lanes Measure the intersection sight distance from that point The observer with the sighting rod stands at the center of the approaching lane at the point determined above The observer s eyes should be at the top of the sighting rod The assistant walks away from the observer along the intersecting roadway toward approaching traffic The assistant should stop periodically and place the target rod on the pavement for sighting by the observer This process should continue until the top of the target rod can
86. More information about collecting travel time and delay study data is contained in the PC Travel for Windows Reference Manual Stop the run by pressing the DO button on the TDC 8 when you have reached the end of the route If the end 1s the last intersection remember to press the button as you depart the intersection This ends the run and the TDC 8 stops collecting data until you press the DO button again signifying the start of a new run Turn around and collect data in the other direction using the same nodes for both directions In this case you press the DO key when you go by the first intersection the END node of the previous run press the New Link button as you go through each of the nodes and press the DO button to end the run when you get to the last node the START node of the previous run Note Remember that you press the DO button to start and stop a run You press the New Link button for nodes in between Repeat steps 6 amp 7 until you have completed the recommended number of runs then just turn off the TDC 8 The TDC 8 is then downloaded to a computer and the data processed following the procedures outlined in the PC Travel for Windows Reference Manual ANALYSIS From the data collected the analysis program determines the time spent stopped and the speed at any time or distance The program is thus able to calculate average speed running speed amount of delay number of stops distance and time between traffic signals
87. OE TRAFFIC IMPACT STUDY REPORTS 154 TRAFFIC STUDIES MANUAL Page v March 9 2011 This page Intentionally left blank TRAFFIC STUDIES MANUAL Page 1 March 9 2011 CHAPTER 1 INTRODUCTION PURPOSE This manual will be used to establish minimum standards for conducting traffic engineering studies on roads under the jurisdiction of the Wyoming Department of Transportation WYDOT In addition local governmental agencies are recommended and encouraged to use the Traffic Studies Manual as a guideline in conducting traffic engineering studies within their area of responsibility AUTHORITY Federal Code of Regulations 23 CFR 655 603 Wyoming Statute 31 5 112 Manual on Uniform Traffic Control Devices for Streets and Highways 2009 Edition MUTCD Wyoming Department of Transportation Operating Policy Policy Number 25 1 SCOPE This manual affects the WYDOT Traffic Program WYDOT District Traffic Offices WYDOT Planning Program and anyone else who performs traffic studies on the state highway system in Wyoming BACKGROUND Section 1 09 of the MUTCD recommends that early in the processes of location and design of roads and streets engineers should coordinate such location and design with the design and placement of the traffic control devices to be used with such roads and streets The decision to use a particular device at a particular location should typically be mad
88. PORT Proper documentation of all activities that have taken place from the initial allegation of a problem through the warrant analysis 15 extremely important A traffic signal study report which includes the following elements as needed should be prepared a Cover Title page that is signed and sealed b Description and map of intersection being considered c Existing conditions and a diagram sketch see Chapter 5 d Crash analysis and Collision Diagram see Chapter 7 TRAFFIC STUDIES MANUAL Page 6 March 9 2011 2 3 4 2 8 1 Warrant analysis see Chapter 3 Statement of use of 70 or 100 percent requirements Discussion of number of approach lanes used in the analysis Discussion of how right turns are considered 1 the analysis Analysis discussion of Warrants 1 9 only those applicable Discussion of delay study Discussion of capacity analysis with Synchro or HCS f Recommendations including sketch if applicable g Supplemental information or data to be submitted as appropriate e Completed Traffic Signal Warrants worksheets Form TR 01 e Turning movement counts for the existing intersection 8 hour A M Noon and P M peaks e Projected turning movement counts for the proposed intersection A M Noon and P M peaks if applicable 24 hour machine counts Pedestrian counts 9 hours Color photos of each approach Projected traffic data for new intersection 1f applicable Pertinent suppl
89. Page 4 76 Volumes Used for This Signal Warrant Study Major Street Totals Minor Street Totals Pedestnans Across Major Street 6 00 7 00 am 7 00 8 00 am 8 00 3 00 am 3 00 10 00 am 10 00 11 00 am 11 00 12 00 n 12 00 1 00 pm 1 00 2 00 pm 2 00 3 00 pm 3 00 4 00 pm 4 00 5 00 pm 5 00 5 00 pm 6 00 7 00 pm AVERAGE STOPPED TIME BY APPROACH FOR MINOR STREET NB SB 6 00 7 00 am 65 1 00 5 00 8 00 9 00 9 00 10 00 I M 10 00 11 00 am 4 11 00 12 00 n 13 01 12 00 1 00 pm 1 00 2 00 pm 2 00 3 00 pm 3 00 4 00 pm 4 00 5 00 pm 5 00 6 00 pm 6 00 00 pm TRAFFIC STUDIES MANUAL Page 23 March 9 2011 Figure 3 2 Example Traffic Signal Warrants Worksheet Page 5 of 6 ami 01 Revised 3 17 10 Page 5 of 6 MINOR STREET HIGHER VOLUME APPROACH VPH MINOR STREET HIGHER VOLUME APPROACH VPH Figure 4 1 Warrant 2 Four Hour Vehicular Volume MAJOR STREET TOTAL OF BOTH APPROACHES VEHICLES PER HOUR VPH Note 115 vph applies as the lower threshold volume for a minor street approach with two or more lanes and 80 vph applies as the lower threshold volume for a minor street approach with one lane Figure 4C 3 Warrant 3 Peak Hour x 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 MAJOR STREET TOTAL OF BOTH APPROACHES VEHICLES PER HOUR VPH 150 vph applies as the lower threshold volume for a minor
90. UDIES MANUAL Page 59 March 9 2011 10 3 LEFT TURN OPERATION Left turns at signalized Intersections can be operated In one of several modes 1 2 3 10 4 Permissive only When permissive only left turn mode 15 used left turn arrows provided Left turns are made during the circular green indication when gaps in opposing traffic permit Protected only left turn phasing Protected only left turn phasing is a left turn operation in which a protected green arrow interval is provided and left turns may be made only when the green arrow is displayed Since no left turn demand is accommodated during the through green interval protected only mode left turn phasing requires longer left turn phases thus increasing delays to the left turning vehicles there are fewer opportunities to turn left as well as the conflicting through phases through traffic has to wait longer for the left turn movements to clear and that drives up the minimum cycle length needed to serve all of the traffic movements at the intersection This type of left turn phasing is the most restrictive and causes the most over all delays and should be limited to intersections where geometric conditions or extremely high opposing volumes do not allow permissive left turn movements to be made safely It is typically reserved for intersections that have opposing dual left turn lanes without sufficient positive offset for drivers of left turning vehicles to see past
91. URISDICTION RELEATED COS ES 22 553 95 8 5002199 8 9000500 a kaa doutes 117 16 2 CANVAS PUBIC OPPO STON cca u ul su ua E 117 16 355 SIGINNAIZREMONVAE DECISPION bes 118 1624 TNTERSECTIONCONIROL ALTIERNATINES u u een 118 TWOWAYX STOP CONTROE TWSC su ay od 118 1022 ALL WAY STIOPCONIROL dAWSGC 118 164 3 ROUNDABOUT CON ER Olga a 118 lo REMOVAL PROC BUR 119 PUBLIC NO FICATION 119 16 5 2 INS EALIZINTERINUCONEROD 119 16 29 MONITOR CRASHES Sa muu 120 SIGNAL REMOVAL ANALYSIS WORKSHEEBTIS 55 ae ele a 121 STAGE b INTERSEG HON TINY ENT OR Year Z u u y d ei u 121 STAGE 2 PRELIMINAR Y SCREENING 121 STAGE 3 DETAILED ANALYSIS TWO WAY STOP CONTROL 122 TRAFFIC STUDIES MANUAL Page 1 March 9 2011 SIAGE SJ EXPECTED INFLUENCE ON CRASHES ui
92. Vs T 5 motorcycle truck includes single units with 6 or more tires buses RVs and pickups pulling trailers semi truck tractor trailer combinations SPEED STUDY WORKSHEET The Speed Study Worksheet has been developed to simplify and automate the processing of speed study field data This helps reduce the chances of errors in the processing as well The worksheet 1s an Excel spreadsheet with an input sheet and display sheets for each direction of travel as well as the combination of both directions analyzed AII data 1s entered on the input sheet and the results are displayed on the display sheets for printing The location related data is entered at the top of the Input sheet from the data on the Speed Study Data Collection Sheet An example of the data input sheet for the previous field data collection sheet is shown in Figure 13 3 Enter the lowest speed recorded and the highest speed recorded This will help adjust the display of output data so that it 1s relatively centered in the display graph If the difference between the highest and lowest recorded speeds exceeds 40 mph an error message will display The number of observations at each respective speed 15 then entered under the appropriate direction column If no vehicles were observed at a given speed the respective line can be left blank or a zero 0 can be entered The Speed Study worksheet is designed to analyze speed statistics for each direction of travel as wel
93. X b Under sub section B enter the number of correctable crashes that have occurred at the intersection each year and select X if there have been more than five correctable crashes in a 12 month period Crashes that are considered susceptible to correction are typically crashes involving either crossing or left turning vehicles from the minor street being struck by through vehicles on the major street See Chapter 7 regarding crash studies WARRANT 7 Crash Experience SATISFIED 5 NO X A ADEQUATE TRIAL OF ALTERNATIVES WITH SATISFACTORY OBSERVANCE AND FULFILLED ENFORCEMENT HAS FAILED TO REDUCE THE CRASH FREQUENCY AND Yes B MINIMUM REQUIREMENT NUMBER OF CRASHES 5 OR MORE CRASHES IN 12 MONTHS 3 crashes 2007 4 crashes 2008 7 crashes 2009 ONE WARRANT WARRANT 1A MINIMUM VEHICULAR VOLUME B CR Select X if there have been 5 or SATISFIED AT WARRANT 1B INTERRUPTION OF CONTINUOUS TRAFFIC more correctable crashes 12 80 WARRANT 4 PEDESTRIAN VOLUME Yes month period 5 peak four hour volumes must be plotted on Figure 4C 1 if the full warrant criteria is used or Figure 4 2 if the reduced 70 criteria is used The peak one hour volumes must be plotted on Figure 4C 3 if the full warrant criteria is used or Figure 4C 4 if the reduced 70 criteria is used These figures can be found under the 5 Full or Pg 5 70 tabs in the Traffic Signal Warrants worksheet F
94. adjacent signalized intersections d Highway and intersection geometry turn lanes e Distance to pedestrian crossings and distance pedestrians have to cross Conversely local conditions may on rare occasions dictate installation of a signal when the minimum volume warrants are not met for the required eight hours An example of this situation is the entrance to a plant or office complex which generates sufficient traffic such as work trips to meet volume warrant criteria for several hours of the day but less than the full eight hours for at least each weekday These locations should be designed with an operation plan which may include flashing operation during hours when full signal control is not justified See Warrants 2 and 3 Sections 3 9 and 3 10 in Chapter 3 It is very important to note that even when a traffic signal 1s justified e g it satisfies one or more warrants it may not contribute to the safety and efficiency of the roadway Closely spaced intersections in high volume corridors could all meet volume warrants but signals are not desirable at every cross street Signals can be poorly designed ineffectively placed improperly operated and poorly maintained Any of these conditions can negate the benefits intended by the traffic signal installation The traffic engineer should also be increasingly aware of energy conservation and include these thoughts when signalization 1s considered PREPARATION AND APPROVAL OF STUDY RE
95. age 136 March 9 2011 INTERSECTION TOTAL IDLING DELAY VEH HRS PER HR Figure 16 13 Idling and Total Delay Four way Intersection Four lane Major Two lane Minor INTERSECTION TOTAL IDLING DELAY LEGEND SIGNAL LLLI aa el 4 Pa vi mt E mE MES a E SIDE ROAD VOLUME PER APPROACH VPH TRAFFIC STUDIES MANUAL Page 137 INTERSECTION TOTAL DELAY VEH HRS PER HR INTERSECTION TOTAL DELAY LEGEND SIGNAL TWO WAY STOP 0 100 150 200 250 300 SIDE ROAD VOLUME PER APPROACH VPH March 9 2011 TOTAL STOPS STOPS PER HOUR Figure 16 14 Stops and Excess Fuel Consumption Four way Intersection Four lane Major Two lane Minor INTERSECTION TOTAL STOPS st i F E LE m P Fa SIDE ROAD VOLUME PER APPROACH TRAFFIC STUDIES MANUAL Page 138 TOTAL INTERSECTION FUEL CONSUMPTION GAL PER HR TOTAL INTERSECTION EXCESS FUEL CONSUMPTION LEGEND TWO WAT STOT LL LLL EL EL LE ul 2 Al i Y _ aces Pa x P uw SIDE ROAD VOLUME PER APPROACH VPH March 9 2011 Figure 16 15 Idling and Total Delay T Intersection Four lane Major Two lane Minor INTERSECTION TOTAL IDLING DELAY LEGEND SIGNAL TWO WAY STOP
96. al should be determined prior to the design of the signal and should be included in the Traffic Signal Reconnaissance Report The primary operational parameters of an intersection traffic control signal consist of 10 2 1 2 3 4 5 6 Controller phasing including provisions for pedestrians Pretimed versus actuated control Local detection alternatives Isolated versus system operation coordination Use of flashing operations CONTROLLER PHASING The phasing selected for implementation at a given intersection should consider the roadway volumes amount of turning traffic pedestrian activity and geometric conditions Phase sequence plans range from relatively simple two phase to phasing plans utilizing one or more left turn and or right turn movements to phasing plans utilizing exclusive vehicle and or pedestrian phases As a general rule the number of phases should be held to a minimum When determining the phasing to be used at a traffic control signal both vehicular and pedestrian movements must be considered For pedestrian movements whether or not to provide pedestrian indications at the intersection is the first decision If no pedestrian indications are provided any permitted pedestrian movements are controlled by the vehicular signal indications For vehicular movements whether or not to provide separate left turn or right turn phases 1s the first decision If left turn and or right turn phases are to be p
97. all be a multiple of 5 mph There are two acceptable methods for determining the advisory speed on an existing horizontal curve use of the design speed equation and the ball bank indicator method The most common method is the ball bank indicator method but for newer roadways where the curve radius and super elevation are known the design speed equation can be used effectively Table 11 1shows the maximum ball bank reading and lateral acceleration to be used when determining the advisory speed on curves These readings are the usually accepted limits beyond which riding discomfort will be excessive and loss of vehicle control might occur The ball bank readings are read directly from the ball bank indicator while traveling the curve at a set speed The lateral acceleration 15 the same value that is used in the design speed equation see Equation 11 1 Table 11 1 Recommended Criteria for Curve Advisory Speed Determination Speeds mph Ball Bank Reading Lateral Acceleration g 12 0 21 0 17 Source Adapted from Carlson and Mason 1999 It 1s important to note that advisory speed criteria are based on driver comfort more than safety A sufficiently skillful driver may be able to traverse a curve on dry pavement at a speed considerably higher than the advisory speed without exceeding the friction capabilities of the pavement However most drivers would choose not to drive at a higher speed because they would experience uncomfortab
98. ally this observation should be made during the hours of the day when the operational concerns were reported to have occurred Photographs of each approach often save subsequent trips back to the study location 3 With an understanding of the operation and a representation of conditions at the location the engineer is in a position to determine if a real problem exists or no further investigation 15 warranted If it is decided after the field investigation that no problem exists the engineer should respond either in writing or verbally to that person responsible for the initial contact regarding the site However should it be determined that further investigation is warranted the engineer should continue the investigation At this point the engineer should notify the concerned TRAFFIC STUDIES MANUAL Page 3 March 9 2011 2 4 1 2 2 4 1 1 2 2 4 2 1 2 party ies of his her Intention to investigate the site for possible signalization and inform them of an approximate completion date ESTABLISHING BASIC AREAS OF CONCERN Establishing the basic area s of concern draws a great deal from the traffic engineer s experience and judgment Some cases can be easily diagnosed such as excessive vehicle delays Other cases are more subtle in nature Of course the issue under consideration may be the result of more than one basic area of concern Decisions made by the traffic engineer at this point will provide the basis f
99. an be purchased from Florida Department of Transportation Maps and Publications 605 Suwannee Street Mail Station 12 Tallahassee Florida 32399 0450 Phone 850 414 4050 Fax 850 487 4099 This Wyoming adaptation of that manual has significantly modified the original manual 1 DISTRIBUTION The official recipients of this manual will be the District Traffic Engineers District Traffic Technicians Traffic Program managers and staff TRAFFIC STUDIES MANUAL Page 1 March 9 2011 11 ADDITIONAL COPIES Consultants and other public users may request copies of the manual from Wyoming Department of Transportation Traffic Program 5300 Bishop Blvd Cheyenne WY 82009 Phone 307 777 4491 Fax 307 777 3993 2 REVISIONS AND ADDITIONS 1 The State Traffic Engineer both Assistant State Traffic Engineers District Traffic Engineers and the Traffic Studies Engineer will constitute the Manual Review Committee 2 The Traffic Studies Engineer will periodically review amend or revise the manual to ensure its compatibility with current technology and state of the art methods and practices 3 Comments or suggestions for improving the manual may be submitted in writing to the Traffic Studies Engineer 5300 Bishop Blvd Bldg 6101 Cheyenne W Y 82009 along with appropriate supporting information or data Any time a revision 15 initiated by the Traffic Studies Engineer comments will be solicited from the District Traffic Engineers and any ot
100. ank indicator method 1s the most common and practical way of determining advisory speeds on older existing curves The ball bank indicator consists of a curved glass tube which is filled with a A weighted ball floats in the glass tube The ball bank indicator is mounted in a vehicle and as the vehicle travels around a curve the ball floats outward in the curved glass tube The movement of the ball is measured in degrees of deflection and this reading is indicative of the combined effect of superelevation lateral centripetal acceleration and vehicle body roll as shown in Figure 11 1 The amount of body roll varies somewhat for different types of vehicles and may affect the ball bank reading by up to 1 but generally is insignificant if a standard passenger car is used for the test During testing the device is mounted in a vehicle and ball bank readings are taken at different speeds along a curve to determine the comfortable traveling speed Figure 11 1 Factors Affecting Ball Bank Indicator Reading Centripetal Acceleration Ball Bank Indicator angle p Body roll angle Superelevation angle Centripetal acceleration angle TRAFFIC STUDIES MANUAL Page 71 March 9 2011 2 3 4 5 6 In order to negate any errors caused by vehicle body roll when using this technique it is best to use a typical passenger car rather than a pickup truck van or sports utility vehicle The equipment and per
101. ant 8 Roadway Network Warrant 9 Intersection Near a Grade Crossing Traffic signals should not be installed unless one or more of these nine warrants are satisfied Because these are minimum requirements satisfaction of a traffic signal warrant or warrants shall not in itself require the installation of a traffic control signal Delay congestion crash experience confusion or other evidence of the need for right of way assignment must be shown Geometric changes which may eliminate the need for a signal should be considered A warrant 15 a set of criteria which can be used to define the relative need for and appropriateness of a particular traffic control device i e STOP or YIELD sign traffic signal etc Warrants are usually expressed in the form of numerical requirements such as the volume of vehicular or pedestrian traffic A warrant normally carries with it a means of assigning priorities among several alternative choices There are two fundamental concepts involved in this determination a The most effective traffic control device is that which 15 the least restrictive while still accomplishing the intended purpose For instance geometric changes alone may negate the need for a traffic signal b Driver response to the influences of a traffic control device has been previously identified by observation field experience and laboratory tests under a variety of traffic and driver conditions Warrants should be viewed as guid
102. antageous when intersections are unfavorably located within a progressive pretimed system or where interruption of the major street traffic is undesirable and must be held to a minimum in frequency and duration 10 8 3 FULLY ACTUATED CONTROL Fully actuated control is best suited to isolated signalized intersections that will operate in a free or isolated not coordinated with adjacent signals mode and where approach speeds are greater than 35 mph It is also appropriate for complex intersections where one or more movements are sporadic or subject to variations in volume 10 9 ISOLATED VERSUS SYSTEM OPERATION 1 Whether a traffic signal will be operated as part of a system or isolated depends on whether coordination with other traffic control signals Is needed An isolated traffic control signal is one in which the signal intervals and or timing plans operate independently of any other traffic control signals System operation is when there is some form of communications system between groups of traffic control signals used to coordinate the signal intervals 2 The MUTCD recommends that traffic control signals that are within 0 5 miles of one another along a major route or in a network of intersecting major routes should be coordinated Although the MUTCD references a 0 5 mile separation effective coordination can occur where signals exceed a mile apart Such coordination is especially effective where roadside friction is minimal speeds are fa
103. aracteristics will dictate whether an approach should be considered as a one lane approach or a two lane approach For a minor street approach with one lane plus a left turn lane engineering judgment would indicate that it should be considered a one lane approach if the traffic using the left turn lane is minor In such a case the total traffic volume approaching the intersection should be applied against the signal warrants as a one lane approach The approach should be considered two lanes if approximately half of the traffic on the approach turns left and the left turn lane is of sufficient length to accommodate all left turn vehicles Similar engineering judgment and rationale should be applied to a street approach with one lane plus a right turn lane In the case of a right turn lane engineering judgment must also be exercised relative to the degree of conflict of minor street right turn traffic with traffic on the major street Thus right turn traffic should not be included in the minor street volume if the movement enters the major street with minimal conflict In such cases the approach would be evaluated as a one lane approach and only the traffic in the through left turn lane considered In some cases the minor street approach may not be striped with multiple lanes but may be of sufficient width typically 18 feet or more to allow right turning traffic to pass to the right of any left turn or through traffic and complete their turn with
104. arsely populated areas the traffic volumes can tend to fluctuate excessively throughout the day and throughout the peak periods of the day Therefore when modeling intersections using Synchro or 5 the actual peak hour factor for each movement should be used for the analysis rather than relying on the software s default peak hour factors If the intersection 1s included in a linear arterial highway under study for progression is part of a erid network or is part of an interchange with coordinated signals at each ramp terminal a Synchro analysis should be conducted Synchro optimizes signal progression and is capable of design and analysis of multiphase actuated as well as two phase fixed time signal control It 15 advisable to examine all legitimate phasing patterns and determine the optimal cycle length for an intersection regardless of whether it is isolated or part of a network This may result in significant time savings because model output can be used to determine input values and ranges necessary to run Synchro more effectively and more efficiently An economic analysis cost effectiveness should be conducted in conjunction with the computer analyses and before proceeding to the implementation stage Unfortunately constraints beyond the engineer s control may sometimes not permit implementation of the best alternative Although input from the local agency is usually received through the traffic signal request in all cases the
105. aused an easily removed obstruction e g overgrown foliage or all way stop control or a roundabout 15 planned after signal removal consider this criterion satisfied and proceed to the next step In the screening process 16 2 2 SPECIAL SITE CONSIDERATIONS 1 2 3 The intersection should be reviewed to determine if any special site conditions exist that would make signal removal institutionally infeasible Two major types of recurring conditions are of special concern a Signals located at major traffic generators especially employment sites where sharp peaks occur during commuting periods and problems in crossing or entering the main road are perceived for these short periods b Signals located near special generators which generate either substantial or special categories of pedestrian traffic as perceived by those opposing removal Examples would include schools libraries homes for the elderly hospitals etc At these locations it may be best to first discuss the proposed removal with representatives of the affected employment site school or neighborhood association prior to making an in depth study While the special pedestrian situations are the most common type generating intense emotional opposition it is very possible that the safety of the general pedestrian traffic may also be an issue that 1s brought up by signal removal opponents Regardless of the number of pedestrians that actually cross the major
106. c characteristics and control for example signals and other control devices and the length of the roadway segment under consideration speed limit changes should not be too frequent or applied to very short road segments If the regulation of speed 15 to be effective the posted limit must be generally consistent with speeds that drivers feel are safe and proper Enforcement is widely recognized to be crucial to the success of speed limits as a means for making roads safer If law enforcement officers and the courts are confident that speed limits have been developed on a reasonable basis their enforcement of the limits will be more effective Generally speed limits should be set at levels that are self enforcing so that law enforcement officials can concentrate their efforts on the worst offenders One of the factors considered very important for setting a speed limit is the prevailing vehicle speed The MUTCD is quite explicit stating that when a speed limit within a speed zone 15 posted it should be within 5 mph of the 85th percentile speed of free flowing traffic The Speed Study output sheets show the recommended speed limit based on this criterion The MUTCD indicates other factors may also influence the appropriate speed limit including roadway characteristics such as shoulder condition grade alignment and sight distance the pace roadside development and environment parking practices and pedestrian activity and reported crash
107. ce measured along the centerline between two points 3 5 feet above the pavement on a line tangent to the embankment or other obstruction that cuts off the view on the inside of the curve Where centerlines are installed and a curve warrants a no passing zone it should be so marked where the sight distance is equal to or less than that listed 1n Table 12 1 The beginning of a no passing zone 15 the point at which the sight distance 15 less than specified in Table 12 1 The end of the zone 1s the point at which the sight distance again becomes greater than the minimum specified In no case shall a no passing zone marking be less than 500 feet in length If the actual no passing distance is less than 500 feet the additional length of marking shall be added to the beginning of the zone Where the distance between successive no passing zones 15 less than the minimum distance between no passing zones as shown in Table 12 1 the appropriate no passing marking one direction or two directions should connect the zones Table 12 2 Minimum Distance between No passing Zones POSTED SPEED LIMIT mph DISTANCE Use for highways posted 65 mph 12 3 ESTABLISHING NO PASSING ZONES 1 2 3 WYDOT policy for establishment of no passing zones on State highway system 15 to use the minimum passing sight distance associated with the posted speed limit on the roadway being checked expect on highways that are posted at 65 mph where t
108. conceptual design should reflect any special needs or conditions the local agency requires TRAFFIC STUDIES MANUAL Page 8 March 9 2011 2 9 1 2 2 10 1 2 3 4 TRAFFIC SIGNAL RECONNAISSANCE REPORT Upon completion of the conceptual traffic signal design process a design reconnaissance report should be prepared This report should include the following elements as a minimum a elements of the traffic signal study report show report in the Appendix b Additional data collected if any c Description of alternatives d Description of analyses including appropriate output from Synchro SIDRA VisSim or HCS e Recommendations of engineer f Work to be performed e Approval of recommended concept This report should be distributed to the State Traffic Engineer both Assistant State Traffic Engineers Traffic Studies Engineer District Traffic Engineer and Electrical Operations Engineer If the project involves geometric changes such as ADA modifications corner radii improvements or the addition of turn lanes the Highway Development Engineer should be included in the distribution because Project Development will need to be involved with the geometric project design and administration IMPLEMENTATION Actual implementation of the improvement should take place as soon as possible after the traffic signal study report and design reconnaissance report stages Conditions change with time and if to
109. cting speed study data fill out the heading of the Speed Study Data Collection Sheet completely The observer enters tally mark V in a data block under the appropriate direction for each observance of a speed If more than 15 vehicles are observed at any particular speed in one direction tally marks slanting in the opposite direction can be entered over the tally mark previously entered thus forming an X which represents two vehicles observed at that speed An example of a completed Speed Study Data Collection Sheet 15 shown in Figure 13 2 If there 1s no interest 1n knowing the speed statistics for each direction but only the combined directions then all speed observations for both directions of travel can be entered in one column This avoids having to add the number of tally marks from the two directions when entering the data into the Speed Study Worksheet TRAFFIC STUDIES MANUAL Page 86 March 9 2011 Form 10 MILES PER HOUR Figure 13 1 Blank Speed Study Data Collection Sheet SPEED STUDY DATA COLLECTION SHEET Wyoming Department of Transportation CITY ROUTE POSTED SPEED COUNTY LOCATION COMMENTS NOTE This sheet is not for computer data entry Print out and use for field data collection DIRECTION OF TRAVEL OBSERVER DATE TIME TO WEATHER DIRECTION OF TRAVEL OBSERVER DATE TIME TO WEATHER Enter the lowest anticipated measured freeflow speed in the red square Must be a multiple of 5 MPH
110. ction and another in the opposite direction two Study Groups will usually be created when the data is read from the traffic data collector Timex X mph Total time the vehicle spent at or below the given speed There are three speed categories which you can set for different purposes You can measure stopped delay time vehicle is stopped by setting Category 1 to 0 mph You can measure queue delay by setting Category 2 to 7 mph The third category might be set to 30 mph to show how much time vehicles spent in car following mode rather than free flow assuming free flow speed is 40 or 45 mph Many other uses for these three categories are possible limited only by your imagination Total Delay Difference between actual travel time and ideal travel time Actual travel time is calculated from the data The ideal travel time is based on the Normal Speed set at the beginning of the study Travel Time The elapsed to travel between two points in seconds This is probably the most fundamental of the reported statistics It is measured directly in the field 14 5 STUDY PROCEDURES 1 2 3 4 5 conduct travel time delay study must first define study area selecting all control points before beginning the study The time periods recommended for studies are A M and peak hours as well as off peak hours in the direction of heaviest traffic movements other times may be requested by th
111. d at an intersection crossing maneuver left turn maneuver and right turn maneuver When a driver 1s completing a crossing maneuver there must be sufficient sight distance in both directions available to cross the intersecting roadway and avoid approaching traffic The sight distance required for this maneuver is based on the distance approaching vehicles will travel on the major road during the time it takes a stopped vehicle to clear the intersection Table 6 2 lists the recommended sight distances for this maneuver based on design speeds The left turn maneuver requires first clearing the traffic on the left then entering the traffic stream from the right The required sight distance for this maneuver is affected by the amount of time it takes the stopped vehicle to turn left clearing traffic from the left and reach average running speed without affecting the speed of an approaching vehicle from the right Table 6 2 lists the recommended sight distances for this maneuver based on design speeds The right turn maneuver must have sufficient sight distance to permit entrance onto the intersecting roadway and then accelerate to the posted speed limit without being overtaken by approaching vehicles from the left Table 6 2 lists the recommended sight distances for this maneuver based on design speeds Table 6 2 Intersection Sight Distance STOP Controlled Sight Distance for Left Sight Distance for Crossover Turn Maneuver feet and Right Turn
112. d result in improved safety and efficiency during the transition and it draws attention to the traffic engineering activities particularly safety and energy efficiency that benefit the area TRAFFIC STUDIES MANUAL Page 9 March 9 2011 This page Intentionally left blank TRAFFIC STUDIES MANUAL Page 10 March 9 2011 3 1 1 2 3 2 1 2 3 4 5 CHAPTER 3 TRAFFIC SIGNAL WARRANT ANALYSIS PURPOSE Section 4C 01 of the MUTCD requires that an engineering study of traffic conditions pedestrian characteristics and physical characteristics of the location shall be performed to determine whether installation of a traffic control signal is justified at a particular location This chapter provides a procedure to determine input into the decision of whether or not conditions warrant the installation or the continued operation of a traffic signal TRAFFIC SIGNAL WARRANT ANALYSIS The MUTCD requires that the investigation of the need for a traffic control signal shall include an analysis of factors related to the existing operation and safety at the study location and the potential to improve these conditions and the applicable factors contained in the following traffic signal warrants Warrant 1 Eight Hour Vehicular Volume Warrant 2 Four Hour Vehicular Volume Warrant 3 Peak Hour Warrant 4 Pedestrian Volume Warrant 5 School Crossing Warrant 6 Coordinated Signal System Warrant 7 Crash Experience Warr
113. d the total 15 divided by the number of differences N 1 to provide the average range in running speed for the initial data TRAFFIC STUDIES MANUAL Page 99 March 9 2011 This procedure is represented by the following equation pa N 1 Example Run t RS Absolute Difference 1 38 0 2 35 3 3 32 3 4 33 1 5 36 3 10 Total S R S N 1 10 5 1 2 5 Where RS Averagerunning speed mph Average range in running speed in mph S Sum of absolute differences N Number of completed test runs 7 The approximate minimum sample size is selected from Table 14 1 for the calculated average range in running speed and the desired permitted error If the required sample size is greater than the number of runs made then additional runs must be performed under similar traffic and environmental conditions to reach the minimum sample size 8 The specified permitted error for traffic operations studies involving efficiency 1 timing studies should be 3 0 mph 9 The permitted error for before and after studies should be 3 0 mph for studies predominately involving efficiency and 2 0 mph for studies predominately concerned with safety 10 X Table 14 1 also includes ranges for specified permitted errors of 4 0 mph and 5 0 mph These data are provided as background information for the traffic engineer There may be special projects where the traffic engineer would deem it appropriate to use one of these
114. d to the target rod If the target rod 1s visible the approach sight triangle for the intersection is appropriate If the top of the target rod 15 not visible the assistant holding the target rod should walk toward the intersection along the centerline of the intersecting lane until the observer can see the target rod When the target rod is visible the position should be marked and the distance to the intersection should be measured along the centerline of the roadway This is the X dimension The analysis of intersection sight distance consists of comparing the recommended sight distance to the measured sight distance The measured sight distance should be equal to or greater than the recommended stopping sight distance If the measured sight distance is less than the recommended sight distance some mitigation may be required Some mitigation measures are as follows a Remove modify obstruction b Reduce speeds Note posting lower speed limits alone is seldom effective c Install traffic control devices if warranted by the MUTCD TRAFFIC STUDIES MANUAL Page 39 March 9 2011 6 3 2 1 2 3 4 5 6 7 9 INTERSECTIONS CONTROLLED WITH STOP SIGNS Vehicles stopped at an intersection must have sufficient sight distance to permit a safe departure At intersections with stop sign control close attention should be given to departure sight triangles Three maneuvers can be completed by vehicles stoppe
115. e District Traffic Engineer These studies should be made during reasonably good weather so that unusual conditions do not influence the study Also since crashes or other unusual delays will produce erroneous results any runs made during such an occurrence should be terminated and another run conducted These studies should be conducted during average or typical weekday traffic conditions When conducting a travel time and delay study the floating car technique should be used In using the floating car technique the driver floats with traffic by passing as many vehicles as pass the test car The idea is to emulate an average driver for each section of roadway In order to determine the number of runs required for statistical significance the engineer analyst should use the following method a Estimate the number of runs required by using Table 14 1 b Conduct the runs c Calculate the average range in running speed R using the equation below d Using the average range in running speed as calculated again use Table 14 1 to determine the number of runs required Make additional runs if required f Engineering judgment should also be used in applying this procedure to fit the purpose of the study To elaborate on 4 c after the first group of running speeds has been computed the absolute differences between the first and second values the second and third values etc are obtained These differences are summed an
116. e No 1 Groups Printed All Vehicles N Main N Main 5th St 5th St Northbound Southbound Eastbound Westbound Start Time Left Thru Right Peds Left Thru Right Peds Left Thru Right Peds Left Thru Right Peds Pd 07 00 AM 12 73 6 0 31 57 4 0 15 37 11 0 10 14 29 0 299 07 15 19 48 6 0 31 51 12 1 9 40 24 1 15 27 44 0 328 07 30 17 53 11 0 44 76 16 0 13 46 22 1 11 42 19 1 372 07 45 21 77 10 0 67 103 18 0 18 74 29 1 12 40 30 1 501 60 251 33 0 173 287 50 1 55 197 86 3 48 123 122 2 1500 08 00 24 65 13 0 50 78 15 0 11 46 20 1 15 22 25 0 385 08 15 14 59 3 0 28 63 9 0 11 38 25 1 9 34 21 0 315 08 30 12 43 10 0 39 64 13 0 10 37 19 0 9 13 23 0 292 08 45 18 50 10 0 31 57 9 0 9 44 16 0 13 24 32 0 313 Total 68 217 36 0 148 262 46 0 41 165 80 2 46 93 101 0 1305 11 00 23 67 10 0 39 81 11 0 15 42 19 0 15 31 39 0 392 11 15 21 77 7 0 33 69 8 0 13 49 26 0 22 31 32 0 388 11 30 23 86 15 0 45 82 10 1 15 45 22 1 12 32 46 0 435 11 45 30 82 15 0 42 75 11 0 8 43 31 0 17 46 39 0 439 Total 97 312 47 0 159 307 40 1 51 179 98 1 66 140 156 0 1654 12 00 PM 26 101 11 0 36 90 15 0 18 60 25 0 20 47 48 3 500 12 15 PM 17 95 14 2 30 92 9 1 10 28 14 0 17 38 36 1 404 12 30 PM 33 87 14 0 46 84 11 0 25 38 25 0 16 44 27 1 451 12 45 PM 31 88 17 1 46 74 13 0 16 46 19 1 17 35 49 1 454 Total 107 371 56 3 1588 340 48 1 69 172 83 1 70 164 160 6 1809 03 30 PM 27 78 12 0 51 91 7 0 15 34 21 0 16 29 26 2 409 03 45 PM
117. e at which vehicles may enter an intersection 1 headway under all way stop control is limited 16 4 3 ROUNDABOUT CONTROL 1 2 3 The installation of roundabouts in lieu of stop control or even traffic signals has consistently shown a substantial improvement in intersection safety and efficiency Roundabouts are well suited to more 1solated intersections but can also be effective when used in a corridor setting provided they are not used between coordinated signalized intersections One impediment to the construction of roundabouts involves the logistical challenges associated with converting existing intersections Temporary traffic control measures which can be expensive must be implemented during the construction process to maintain orderly and safe traffic flow However this problem can be minimized or avoided by constructing roundabouts when new intersections are first built and when major modifications are proposed for existing intersections TRAFFIC STUDIES MANUAL Page 118 March 9 2011 16 5 REMOVAL PROCEDURE After all of the above areas have been thoroughly considered and if the decision Is made to proceed with the removal the following steps need to be taken 16 5 1 PUBLIC NOTIFICATION 1 2 3 4 5 The Traffic Program District Office Resident Engineer and local governing agency should be advised of the decision and provided with documentation of the above noted areas to support the
118. e on the basis on an engineering study or the application of engineering judgment The MUTCD requires that an engineering study shall be performed by an engineer or by an individual working under the supervision of an engineer through the application of procedures and criteria established by the engineer An engineering study shall be documented This manual will provide a more efficient standardized process for compiling and analyzing data collected during traffic engineering study activities This manual will serve as a basic tool for district traffic operations studies and as a guideline for local agencies in Wyoming This manual will constitute the minimum standards for use in conducting traffic engineering studies on state highways in Wyoming The manual s chapters and data collection sheets are not shown in any particular order Accordingly sections applicable to a specific situation or concern should be considered on an individual basis District Traffic Engineers should ensure that studies performed by their staff or by consultants conform as a minimum to the practices and techniques prescribed by this manual and shall incorporate the manual by reference in consultant contract documents This manual was originally based on the organization and format of the Florida Department of Transportation s Manual on Uniform Traffic Studies FDOT Manual Number 750 020 007 January 2000 as revised March 2003 Copies of the original Florida manual c
119. earest signal Morth fi South ft Will a signal at this location provide the necessary degree af platooning and progression between the adjacent signals East West Street Posted Approach Speed mph Lanes street of the street or highway system that serves as the prircipal roadway network for through traffic flow Does street include rural or suburban highways outside entering or traversing a city Does street appear as a major route on an official street plan Distance to nearest signal East fi West ft Will a signal at this location prowde the necessary degree of platooning and progression between the adjacent signals there diei study that has 5 year projected volumes at this intersection that meet one or more of Warrants 1 2 or 3 during an average weekday Da traffic volumes on a Saturday or Sunday meet or exceed 1000 veh hr for at least 5 hours Is there a designated school crossing across the uncontrolled roadway at this intersection there railroad grade crossing within 140 feet of the intersection on a STOP controlled approach Volume Input Table 10 00 11 00 _ Ll kD i2000 6 00 7 00 am 7 00 8 00 am 00 2 00 am 8 DD 10 00 am 10 00 11 00 am 12 00 1 00 2 00 3 00 4 00 5 00 om 8 00 6 00 pm 6 00 7 00 pm TRAFFIC STUDIES MANUAL Page 16 March 9 2011 If Yes is selected for the question Is there a designated school crossing
120. edicted Changes Average Annual Crash Frequency Following Signal Removal Conversion Two Way Stop Control 60 of MUTCD Minimum Vehicular Volume Warrant Volume Magnitu Hours that Intersection Volumes Excee 1 2 3 4 5 B Annual Average Crash Frequency TRAFFIC STUDIES MANUAL Page 116 March 9 2011 cu 5 Replacing unjustified signal with a roundabout at four legged intersections has the following estimated effects a Total delay 15 reduced by approximately 62 to 74 percent b Idling delay is reduced by approximately 25 percent c Stops are reduced by approximately 25 percent d Fuel consumption 15 reduced by approximately 16 percent 16 3 3 JURISDICTION RELATED COSTS 1 Traffic signal removal is one of those rare activities that actually saves money for the traffic engineering agency 2 The costs of continued signal operation include the annual costs of maintenance electricity and other operational costs such as signal timing Additionally the annualized cost of upgrading the signal display may also be included if it 1s below design standards 3 The cost of signal removal includes the one time costs of removing the signal hardware and installing STOP signs and the annual cost of maintaining the signs 4 These costs vary widely between individual intersections and between jurisdictions When these various costs are properly accounted for and adequate records are kept the jurisdiction
121. ehicle from the instant brake application begins The reaction distance 15 based on the reaction time of the driver and the speed of the vehicle The braking distance is dependent upon the vehicle speed and the coefficient of friction between the tires and roadway Table 6 3 lists minimum recommended stopping sight distances based on design speed and the sum of reaction distance and braking distance rounded to the nearest 5 feet for ease of application At 55 mph for example the recommended stopping sight distance 15 495 feet For stopping distance calculations the height of the driver s eye is 3 5 feet above the roadway and the object height is 2 feet above the roadway surface as illustrated in Figure 6 7 The 2 foot object height represents an object that the driver of an approaching vehicle would want to avoid One element to consider for stopping sight distance is vertical curvature of the roadway On straight roadway sections the obstruction that blocks the driver s vision of the roadway ahead is the vertical curvature of the road surface As the vertical curvature increases stopping sight distance also increases Determine the minimum stopping sight distance for the posted speed limit see Table 6 3 The observer records the date and time posted or operating speed site location and weather conditions on the sight distance diagram TRAFFIC STUDIES MANUAL Page 41 March 9 2011 8 Standing at a pre determined location along the
122. elines not as absolute values Satisfaction of a warrant is not a guarantee that the device 1s needed The warrant analysis process 16 just one of the tools to be used in determining if a traffic signal 15 warranted The application of warrants 15 effective only when combined with comprehensive analysis and evaluation of available pertinent information and the application of appropriate principles provisions and practices as contained in the MUTCD and other sources for the purpose of deciding upon the applicability design operation or installation of a traffic control device as TRAFFIC STUDIES MANUAL Page 11 March 9 2011 6 3 3 1 2 3 3 4 1 2 3 4 noted in the definition of Engineering Study in Section 1A 13 of the MUTCD In all cases at least one or more warrants must be fully met before a traffic signal installation 1s considered Most of the warrants have criteria associated with the number of approach lanes and reduced criteria for rural and or higher speed locations Each traffic signal warrant analysis must determine which criteria apply based on the number of lanes and whether or not the reduced warrant criteria apply Engineering judgment must be used to determine when to apply the reduced criteria and the appropriate number of lanes to use for the warrant analysis APPLICATION OF REDUCED 70 WARRANT CRITERIA The MUTCD allows for the application of reduced 70 traffic signal warrant crite
123. emental information if needed Computer program outputs Guidelines for the content and format of this report are necessary to insure uniform report preparation procedures and to expedite report review time The traffic signal study report should conclude one of the following 1 no problem exists and therefore no traffic signal is warranted 2 a problem exists but the solution 15 not a traffic signal 3 a problem exists and a traffic signal will correct or reduce the problem or 4 a problem exists and a traffic signal in conjunction with other improvements will correct or reduce the problem In the first case the traffic signal study should be terminated and the party initiating the request should be notified It may also be beneficial to disseminate further information explaining the basis of the decision In the second case the traffic signal study should also be terminated another study non signal related should be initiated to resolve the problem and proper notification should be given In the third or fourth case the study should be initiated to resolve the problem and proper notification should be given also the study should be handed over to the engineer s responsible for design It 15 again advisable at this point to notify the party initiating the request so that they are kept informed of the progress of the study DEVELOPMENT OF NEW TRAFFIC SIGNAL DESIGN The design stage includes all activities that take place after justi
124. en established by engineering and traffic investigation shall be documented by a Declaration of Speed Limit Form M 10 An example of a completed M 10 form is shown in Figure 13 6 When declaring a speed limit the 10 form shall be signed by the District Engineer and forwarded to the State Traffic Engineer along with the supporting documentation for concurrence If the State Traffic Engineer concurs the form is then signed and forwarded to the Director for formal declaration of the speed limit After the form is signed by the Director or his designee the form is returned to the district so the appropriate signing changes can be made Enforcement of the new speed limit cannot occur until the appropriate signs giving notice thereof have been erected Once the signing changes have been made the installation date shall be noted on the form and copies of the completed form shall be distributed to the District Engineer District Traffic Engineer State Traffic Engineer and Traffic Studies Engineer It is also recommended that copies be sent to the local Highway Patrol division captain and local law enforcement agency ies for help with enforcement 13 7 MINIMUM SPEED LIMITS WY DOT does not post minimum speed limits TRAFFIC STUDIES MANUAL Page 94 March 9 2011 Figure 13 6 Example of Completed Declaration of Speed Limit Form Form 10 ev 10 00 WYOMING DEPARTMENT TRANSPORTATION DECLARATION OF SPEED LIMIT LOCATION Wyo 2 2 F
125. ered in situations where a Poor internal site design and circulation leads to backups onto the mainline Auto oriented businesses with short drive through lanes or poorly designed parking lots would be prime examples of this situation b The peak hour turning traffic activity 1s unusually high e g greater than 10 percent of the daily total c Operating speeds on the mainline route are high greater than 60 miles per hour and drivers would generally not expect right turns d The driveway or minor public road intersection is difficult for drivers to see e The driveway entrance is gated or otherwise must be entered very slowly f Right turning traffic consists of an unusually high number of trailers or other large vehicles TRAFFIC STUDIES MANUAL Page 151 March 9 2011 e A parallel railroad track is sufficiently close to intersection to cause right turning traffic to queue back onto the through lane s of the highway when trains are using the crossing h The intersection or driveway angle 15 highly skewed requiring a turn of more than 110 degrees i Rear end collision experience 15 unusually high at the location 18 4 OFFSET RIGHT AND LEFT TURN LANES Vehicles in the right turn lane can tend to obstruct the vision of drivers waiting at the stop bar of the minor roadway One way to reduce the obstruction of the minor roadway drivers view is to offset the right hand turning bay to the right Offsetting
126. es and application of the full 10096 or reduced 70 criteria 1t can be concluded that the intersection will not warrant the installation of a traffic control signal and the signal warrant study can be terminated The requestor should be notified of these findings per Chapter 2 Table 3 1 ADT Volumes below which MUTCD Signal Warrants Cannot be Met Vehicles Per Hour on Number of Lanes for Vehicles Per Hour on Higher Volume Minor Moving Traffic on Each Major Street Total of Street Approach One Approach Both Approaches Equivalent ADT Direction Only Equivalent ADT 1 1 50 35 400 2800 150 1405 2400 1680 Waranti 2 or more 420 4800 3360 150 105 2400 1 680 Condition 2 or more 420 4800 3360 200 140 3200 I 500 200 140 3200 C are 750 wass 420 720 504 720 504 420 1 600 600 500 waman Warrant 1 2 or more 4 0 750 22 600 720 720 _ 600 4 800 Tao 3360 Combination 1A amp 1B 3 For the volumes in Table 3 1 to meet the 8 hour warrant criteria all traffic during the day would have to be concentrated into an 8 hour period with no other traffic during the remaining 16 hours of the day Based on the normal distribution of traffic volumes throughout the day the actual two way ADT volumes needed to meet the 8 hour warrant criteria is significantly higher than those indicated
127. et al 1985 The most prevalent types of crashes that occur on horizontal curves are lane departure type crashes including run off road side swipe meeting and head on crashes The potential for crashes is significantly increased when the safe and comfortable travel speed along a curve is below the posted speed along a tangent segment of the highway This potential tends to increase as the distance upstream of the curve to a previous curve of equal or lower safe and comfortable travel speed increases The primary strategy used by traffic engineers to minimize crashes on horizontal curves is to provide advance warning of unexpected changes in horizontal alignment Motorists are normally advised of maximum recommended speeds along curves through the use of Horizontal Alignment signs and Advisory Speed plaques According to the MUTCD the advisory speed shall be determined by an engineering study Therefore the establishment of advisory speeds on Wyoming state highways must follow the standard procedures developed and adopted by WYDOT field work used for determining the advisory speeds must be performed under the supervision of an engineer This chapter sets forth the procedures to be used to establish the advisory speed on horizontal curves in Wyoming The established advisory speed must be both realistic and safe meeting drivers expectations for a given set of geometric operational and environmental conditions The posted advisory speed sh
128. eter when testing the curve for ride comfort at 50 mph The ball bank indicator must be mounted in the vehicle so that it displays a 0 reading when the vehicle is stopped on a level surface The positioning of the ball bank indicator should be checked before starting any test This can be done by stopping the car so that its wheels straddle the centerline of a two lane highway on a tangent alignment In this position the vehicle should be essentially level and the ball bank indicator should give a reading of 0 It is essential that the driver and recorder be in the same position in the vehicle when the ball bank indicator is set to a 0 reading as they will be when the test runs are made because a shift in the load in the vehicle can affect the ball bank indicator reading TRAFFIC STUDIES MANUAL Page 72 March 9 2011 7 8 9 10 11 The ball bank indicator method is normally a two person operation with one person to drive and the other to record curve data and the ball bank readings especially 1 advisory speeds are being determined for a series of curves Vehicle movement around a curve causes the ball to swing from the zero position e g vehicle movement to the left causes the ball to swing to the right The faster the vehicle moves around the curve or the sharper the curve the greater the distance the ball swings away from the zero degree position Superelevation however tends to bring the ball back to the zero p
129. eview Signalized Intersection Checklist Form TR 18 has been developed to assist with the performance of operational reviews on new or significantly modified traffic control signals Figure 10 2 gives an example of a completed operational review checklist 10 11 2 LEFT TURN PHASE OPERATIONAL REVIEW Whenever protected permissive left turn phasing using 4 section all arrow left turn signal faces 1s installed at an intersection either in a new signal installation or as a retrofit to an existing signal a left turn operational review should be conducted to verify the proper operation of the left turn phases The detector settings and phase timings should be set to minimize the unnecessary activation of the left turn phases while still adequately serving all left turning vehicles A Left Turn Operational Review form Form TR 19 has been developed to assist with the performance of left turn operational reviews Figure 10 3gives an example of a completed left turn operational review TRAFFIC STUDIES MANUAL Page 65 March 9 2011 Figure 10 2 Example of an Operational Review Checklist Operational Review Signalized Intersection Check List Town Reviewed By Date Intersection OK NO COMMENTS Overall Intersection Operation Signal Phasing No Loaded Cycles Clearance Intervals No Skidmarks Evident No Signal Violations Red Light Running Vehicle Detection Works Vehicle Detectors Located Correctly Vehicle Detectors Call Extend Correct Phase s
130. f curb if no edge line Dedicated right tum lane measure to projected parallel edge line or lip of curb if no edge line Dedicated amp well used parking lane measure to projected parallel edge or parking line or inside edge of parked vehicle if no markings Traffic tends to use parking lane as defacto right tum lane measure to projected parallel ip of curb TRAFFIC STUDIES MANUAL March 9 2011 10 8 1 PRETIMED CONTROL Pretimed control is best suited to intersections where traffic patterns are either relatively stable or predictable such that the variations in traffic that do occur can be accommodated by predetermined timing plans without contributing to unreasonable delays or congestion Pretimed control may be justified in the following conditions 1 Two phase operation at intersections in central business district of larger cities 2 When intersection spacing and traffic speeds are favorable and pretimed signals will provide for coordinated traffic flow on the street 3 When coordination 15 needed with adjacent signals on two or more intersecting streets such as on a grid system 4 Where there are large and relatively consistent pedestrian volumes present 10 8 2 SEMI ACTUATED CONTROL Semi actuated control is best suited to signalized intersections along a major roadway with relatively minor cross streets and where the signals are coordinated throughout the day Semi actuated control 1s also adv
131. fication of a new traffic signal installation has been made or the modification of the operation of the existing signal is required These activities which lead up to the traffic signal design reconnaissance report include the following a Collect additional data 1f needed b Develop alternatives c Evaluate alternatives d Select Best alternative e Design improvement TRAFFIC STUDIES MANUAL Page 7 March 9 2011 2 3 4 5 6 7 9 9 For the Installation of new traffic signal the additional data collection will generally be limited to the turning volume counts for 15 minute time periods required for developing the signal operating plan and controller timings Data collected for the signal warrants of course available if needed For modification of an existing signal the data available is often dated so it may also be necessary to collect some of the data elements outlined previously in addition to the turning volumes In any event it 15 advisable to develop alternative concepts prior to the collection of additional data The alternative development evaluation and selection steps are significant steps In themselves and are therefore only addressed in general terms In this manual However the basic approach is presented in order to provide the user with guidelines necessary to properly conduct the traffic signal study reasonable alternative concepts should be considered by
132. following equation can be used to estimate the minor street ADT to be used in the previous steps Y gt Minor Street Volumes ADT yinor street Major Street Volumes ADTyajor street c The total intersection approach volume averaged for the 22 remaining hours is then calculated automatically by the form TRAFFIC STUDIES MANUAL Page 124 March 9 2011 6 7 9 9 10 For the average of 22 remaining hours and using the same nomographs as in Step 3 read from the nomographs the per hour estimates of the four impact variables idling delay total delay total stops and excess fuel consumption Follow the same procedures as Steps 3 a and b except use the volume data for the 22 remaining hours instead of the 2 peak hours a Estimate the four impact variables for signal control using the same procedure as Step 3a For the example use the side road volume of 23 and the main road volume of 361 b Estimate the four impact variables for two way stop control using the same procedure as Step 3b and the same volumes as the previous step For the example use a side road volume of 23 and main road volume of 361 c For each of the four impact variables the difference between signal control and two way stop control is calculated 1 the 6b entries are subtracted from the entries Impacts for the total of the 22 remaining hours are calculated a The total intersection approach volume for the total
133. g the peak hour Delay a Excessive delays experienced by left turning vehicles may warrant left turn phasing Left turn phasing may be warranted if b There 15 at least 2 0 vehicle hours of left turn delay during the peak hour on the approach and c There are at least two left turns per cycle during the peak hour and d The average delay per left turning vehicle exceeds 35 seconds TRAFFIC STUDIES MANUAL Page 60 March 9 2011 3 10 5 1 2 3 4 5 10 6 Crashes a high frequency of crashes between left turning vehicles and opposing through or right turning vehicles may warrant left turn phasing Left turn phasing may be warranted if b On one approach there have been 4 left turn crashes in 1 year or 6 left turn crashes in 2 years On both opposine approaches have been 6 left turn crashes in 1 year or 9 left turn crashes 1 2 years PROTECTED PERMISSIVE LEFT TURN PHASE CONTROL turns that are provided with protected permissive left turn phasing can be controlled by either 5 section doghouse left turn signal faces or with 4 section all arrow signal faces new installations of protected permissive left turn phasing where separate left turn lanes are provided will utilize the 4 section all arrow signal faces protected permissive left turn phasing where the left turns are being made from a shared use left turn and through lane will utilize the 5 section
134. g to the length of gap measured Gaps measured by a stop watch are entered directly into the form as they are measured Gaps measured by an electronic traffic data collector must be downloaded and then transferred to the form Gaps less than the minimum adequate gap do not need to be included on the form however documentation of the availability of gaps that are within a few seconds of the minimum adequate gap can be used for the consideration of possible roadway geometric changes that would reduce the crossing distance e g bulb out curb extensions or narrower lanes or other measures to reduce the minimum adequate gap time needed for a pedestrian to cross the roadway Gaps that are more than twice as long as the minimum adequate gap can be counted as two or more gaps that are longer than the minimum adequate gap For example if the minimum adequate gap is 20 seconds a gap of 43 seconds can be broken into one 20 second gap and one 23 second gap for purposes of the available gap survey The tally marks are then totaled for each gap size greater than the minimum acceptable gap The sum of these totals is the number of gaps of sufficient length to accommodate the crossing of 85 of the pedestrian groups using the crossing at a day and time and under the conditions similar to those of the study The total time of all adequate gaps 15 then determined by multiplying the gap size by the total number of gaps of that size The sum of these totals 15 the
135. grade separated crossing TRAFFIC STUDIES MANUAL Page 26 March 9 2011 Figure 3 4 Example Intersection near Grade Crossing Warrant Sheet Form TR 01b Revised 9 17 10 Page 1 of 1 WYOMING DEPARTMENT OF TRANSPORTATION TRAFFIC SIGNAL WARRANTS INTERSECTION NEAR A GRADE CROSSING WARRANT SHEET Calc by JDT Calc Date 09 17 10 Torrington 2 Goshen Chk by LJR Count Date 6 31 10 CITY DIST CO Major Street Valley Rd US 26 Minor Street E F Street Number of Lanes 1 at Track Crossing Number of Trains Per Day 47 Clear Storage Distance D 85 of High Occupancy Buses on Minor Street Approach 2 of Tractor Trailer Trucks on Minor Street Approach 6 Adjustment Factors Adjustment Factor for Daily Frequency of Rail Traffic 1 33 From MUTCD Table 4 2 based 47 trains day Adjustment Factor for Percentage of High Occupancy Buses 1 09 From MUTCD Table 4C 3 based 2 buses Adjustment Factor for Percentage of Tractor Trailer Trucks 0 75 From MUTCD Table 4 4 based 6 trucks and 85 ft clear storaqe distance WARRANT 9 Intersection Near a Grade Crossing SATISFIED YES NO X 11 12 PM 1PM 3PM 5 PM Minor Sweet Crossing Approach Equvaientven 26 8 34 t t 13 56 55 _ Refer to MUTCD Figure 4C 9 to determine if this warrant is satisfied VPH after applying the adjustment factors in Tables 4C 2 4C 3 and or 4C 4 if appropriate Figure 4C 9 Warrant 9 Inte
136. gram This chapter includes a summary of the Traffic Program s interchange and intersection lighting criteria 15 2 LIGHTING WARRANTS 1 The primary purpose of warrants is to assist administrators and designers in evaluating locations for lighting needs and selecting locations for installing lighting Warrants give conditions that should be satisfied to justify the installation of lighting Meeting these warrants does not obligate the state or other agencies to provide lighting or participate in its cost Conversely local information in addition to that reflected by the warrants such as roadway geometry ambient lighting sight distance signing crash rates or frequent occurrences of fog ice or snow may influence the decision to install lighting 2 Per WYDOT Operating Policy 25 1 WYDOT is responsible for the design installation and maintenance for roadway lighting systems on the state highway system as follows 3 The traffic program has adopted the warrants for freeway lighting that have been established by the American Association of State Highway and Transportation Officials AASHTO in the Roadway Lighting Design Guide 2005 The warrants for freeway lighting contained in the AASHTO Guide are indicated below a On existing traffic signal poles when the lighting system is upgraded to WYDOT standards b On traffic signal poles at new or reconstructed traffic signal installations c Rural intersections of US numbered routes w
137. he city If the intersection is within the urban area boundary of an incorporated city even though it may be outside of the actual corporate limits the city s name should be used b Enter the names and information for each of the approaches Select Yes or No from the dropdown lists in each of the blanks after a question c The posted speed limit on the major street must be input for proper application of the speed based warrant reductions If the speed limit is posted at 40 mph the spreadsheet will ask if the 85th percentile speed exceeds 40 mph This should be determined by a spot speed study see Chapter 13 Select Yes if the 85 percentile speed is greater than 40 mph or No if it is 40 mph or less from the dropdown list next to the question that 15 highlighted in red text d The number of lanes per approach should be determined per Sections 3 4 and 3 5 TRAFFIC STUDIES MANUAL Page 15 March 9 2011 Figure 3 1 Traffic Signal Warrants Input Sheet Fame urat TRAFFIC SIGNAL WARRANTS INPUT SHEET CALC by CALC CHE COUNT DATE CITY DIST North South Street Posted Approach Speed mph Lanes s street of the street or highway system that serves as the pri rcipal roadway network for through traffic Flow Does street include rural or suburban highways outside entering or traversing a city Does street appear as a major route on an official street plan Distance to n
138. he 70 mph sight distance criteria will be used permanent no passing zones on all highways under the jurisdiction of WYDOT shall be determined by the Department s Traffic Program using the Department s Novastar II Range Track Survey System No passing zones on all paved highways under County jurisdiction that have been rebuilt using funds administered by WYDOT shall be determined by the Department s Traffic Program using the Department s range tracking system The request for range tracking shall be in writing from the proper County authority TRAFFIC STUDIES MANUAL Page 80 March 9 2011 4 5 6 12 4 1 2 3 4 5 Other paved county highways that have been reconstructed using other funding sources will be range tracked by the Department s Traffic Program using the Department s range tracking system only upon written request by the proper County authority and after an Authority for Rendering Services ARS agreement has been established with proper charge numbers for billing the County for the range tracking crew s time travel expenses and mileage The letter of request from the County to range track a county highway shall include the posted speed limit s that apply on the roadway being range tracked That is the speed that will be used for the minimum passing sight distance in establishing the length of no passing zones unless the letter specifies the County s desire to establish the no passing barriers at
139. he minimum distance between no passing zones shown in Table 12 2 TRAFFIC STUDIES MANUAL Page 83 March 9 2011 This page Intentionally left blank TRAFFIC STUDIES MANUAL Page 84 March 9 2011 13 1 1 2 3 4 5 13 2 1 2 CHAPTER 13 SPEED STUDIES PURPOSE Title 31 Chapter 5 Article 3 of the Wyoming Statutes establishes the speed regulations for all public roadways in Wyoming Effective July 1 2011 the statutory speed limits are a 20 mph in school zones b 30 mph in urban districts as defined by W S 31 5 102 a lvii c 30 mph in any residence district as defined by W S 31 5 102 a xxxviii d 30 mph in any subdivision pursuant to W S 18 5 304 e 75 mph on interstate highways f 65 mph on all other paved roadways 2 55 mph on all other unpaved roadways The statutes under W S 31 5 302 authorize the director of the department of transportation to establish specific maximum speed limits on localized geographic areas of the state highway system based on engineering and traffic investigations Such speed limits may be greater or less than the normal statutory speed limits for the roadways being considered The statutes also include a basic speed law W S 31 5 301 a prohibiting drivers from traveling at a speed greater than what 1s reasonable and prudent under the conditions and having regard to the actual and potential hazards that may exist which recognizes that drivi
140. her affected offices Their concerns when appropriate will be incorporated into the revision 4 Substantive revisions as determined by the Manual Review Committee will be approved by the State Traffic Engineer following the process established in the Standard Operating Policy 3 FORMS ACCESS We have standardized all of the forms in this manual and they are available in the Forms Library Reproducible copies of all of forms are in the Appendix Form TR 01 Traffic Signal Warrants Worksheet Excel Spreadsheet Form TR 01a School Crossing Warrant Sheet Excel Spreadsheet Form TR 01b Intersection Near a Grade Crossing Warrant Sheet Excel Spreadsheet Form TR 03 Signal Removal Analysis Worksheet e Form TR 04 Worksheet for Estimating Daily Impacts of Signal Removal and Replacement by Two Way Stop Form TR 10 Speed Study Data Collection Sheet Form TR 11 Speed Study Worksheet Excel Spreadsheet e Form TR 12 Pedestrian Gap Study e Form TR 16 Curve Advisory Speed Study e Form TR 17 Rural Intersection Lighting Criteria Form 18 Operational Review Signalized Intersection Checklist Form TR 19 Left Turn Phase Operational Review e Form TR 22 PC Travel Field Worksheet e Form TR 25 Traffic Impact Study Review Checklist TRAFFIC STUDIES MANUAL Page 2 March 9 2011 CHAPTER 2 TRAFFIC SIGNAL STUDY PROCEDURE 2 1 PURPOSE 1 The purpose of this chapter is to prese
141. ian to provide a pedestrian refuge island will provide adequate crossing opportunities for pedestrians The total combined direction gap study see Section 9 5 2 measures the duration of gaps across both directions of vehicular travel This is typically used for pedestrian crossings without median refuge islands MULTI DIRECTION GAP STUDY The standard Gap Study procedure provided in the electronic traffic data collectors such as the JAMAR Technologies TDC 8 or TDC 12 traffic data collectors must be used to perform multi direction Gap Studies The multi direction Gap Study procedure 15 detailed in the respective User s Manual for the TDC 8 or TDC 12 electronic traffic data collector Preferably the study interval should be set to 5 minutes at the beginning of the study to better facilitate the determination of adequate gaps per 5 minute period per the WYDOT Pedestrian and School Crossing Traffic Control Manual 2003 If the study is performed with shorter intervals the final analysis can use longer intervals On the other hand the final analysis cannot be performed on intervals less than those set during the initial study When printing the study data only one direction at a time or the combined direction can be selected in the Gap Print Setup screen or the results will be added together resulting in numbers that are higher than actuality Gap Print Setup General Peak Comments Factor Page Headings Select Interval Length From
142. ic signing The appropriate warning signs for truck rollover concerns require more than just determination of curve advisory speeds for passenger vehicles as previously discussed When a truck rollover problem exists the use of truck rollover signing with a truck advisory speed should be considered It is suggested that the engineering study for truck rollover warning signs address the following considerations a Speed data and advisory speed determinations b Traffic characteristics c Roadway geometrics d Recommended traffic control devices Truck rollover theoretically can occur when the lateral acceleration exceeds 0 30g but no calculated lateral acceleration less than 0 35g has been determined in any truck rollover crashes It is recommended that any posted advisory speed for the truck rollover signing should reflect a ball bank reading of 10 degrees side friction factor of 0 17g for all advisory speeds in order to provide a reasonable factor of safety The use of the 0 17g side friction value 15 about half the critical side friction factor and accommodates those occasions where the truck may exceed the posted truck advisory speed or the truck travels a curve radius that 15 less than the actual roadway curvature The MUTCD provides a number of other devices that can be used in conjunction with Horizontal Alignment signs and Truck Rollover signs to address truck rollover consideration such as a Chevron Alignment signs W1 8
143. ically determined by the Geometrics Engineer in accordance with the AASHTO Green Book 18 6 AUXILIARY PASSING LANES Auxiliary passing lanes can be used to increase passing opportunities on two lane highways Passing lanes are typically applied to a corridor in a systematic approach to provide a passing opportunity at roughly five minute intervals The passing lane system can consist of alternating or offset three lane sections four or five lane sections or a combination of the various sections depending on the various features on the corridor The addition of auxiliary passing lanes 15 typically considered whenever traffic volumes exceed 4 000 vehicles per day Auxiliary passing lanes can also be beneficial on somewhat lower volume highways where there are very high peak travel periods or high volumes of tourist traffic during the peak tourism months The decision as to when and where to place auxiliary passing lanes 15 based the engineering judgment of the Geometrics Engineer and or Studies Engineer with appropriate input from the District personnel and other programs as needed TRAFFIC STUDIES MANUAL Page 153 March 9 2011 18 7 AUXILIARY RIGHT TURN ACCELERATION LANES Auxiliary right turn acceleration lanes allow entering vehicles those that have turned right from a driveway or minor public road onto the major route to accelerate before entering the through traffic flow Acceleration lanes should be provided where free flow right t
144. ide for Left Turn Lanes on Two Lane Highways Speeds gt 60 mph LEFT TURN WARRANTS 60 MPH 50 AASHTO CRITERIA 5 Left Turns 10 Left Turns 20 Left Turns 30 Turns a gt E gt Lil gt l gt un e a e ADVANCING VOLUME VPH 18 2 2 URBAN AND FRINGE AREA GUIDELINES 1 In urban rural urban fringe areas using the 50 left turn lane criteria for lower speed two lane highways can be used to Justify the construction of left turn lanes These criteria are shown in Figures 18 2 and 18 3 The appropriate figure to use is based on the posted speed limit on the highway at the study location The appropriate trend line 15 identified on the basis of the percentage of left turns In the advancing volume rounded up to the nearest percentage trend line If advancing and opposing volume combination intersects above or to the right of this trend line a left turn lane can be considered appropriate 2 Other factors to consider when determining the need for left turn lanes in urban and fringe areas include a Traffic volumes below the respective trend line on the appropriate left turn lane guidelines figure can be used to justify a left turn lane if the opposing through volume is very high if the presence of left turning vehicles would not be expected or if a crash problem associated with left turning traffic exists b Left turn lane
145. igures 4C 1 and 4C 3 are included on the 5 Full sheet for studies that use the full warrant criteria and Figures 4C 2 and 4C 4 are included on the 5 70 sheet for studies that use the reduced 70 warrant criteria a First determine which sheet applies and select the respective tab b On the blank worksheet each figure contains green horizontal lines underlining each of the possible lane configurations Delete the lines that do not apply leaving the applicable lane configuration used for the analysis underlined in green c On the blank worksheet Figures 4C 1 and 4C 2 include four horizontal and four vertical lines each of red blue and green colors which are to be used to plot the appropriate points for analysis Figures 4C 3 and 4C 4 include one horizontal and one vertical line each of red blue and green colors The lines are color coded to mean Red warrant criteria is met e Blue warrant criteria is close to being met 1 the point fall on or just below the curve e Green warrant criteria is not met d To the right of each of the figures a table of data indicates the peak eight hours of data analyzed in the worksheet including how much above or below the curve the point falls for each hour Positive numbers typically fall above the curve while negative numbers typically fall below the curve This data is color coded as previously discussed to TRAFFIC STUDIES MANUAL Page 18 March 9 2011 6
146. in Table 3 1 Normal daily traffic distribution was analyzed to determine the typical 24 hour traffic volumes that would be likely to meet the 8 hour warrant criteria Table 3 2 shows the results of that analysis If the roadway volumes on both approaches meet or exceed the traffic volumes shown on Table 3 2 for the applicable number of lanes and application of the full 100 or reduced 70 criteria 1t does not necessarily mean that a traffic signal is warranted and should be installed but indicates that the intersection should be further analyzed for possible signal warrants a full warrant analysis should be conducted per the remainder of this chapter If the two way ADT volumes on the approaches are less than those shown on Table 3 2 engineering judgment should be used to decide whether the traffic volumes are close enough to need full warrant analysis or the volumes are too low to meet the warrant criteria 120 84 1920 120 84 1920 160 112 2 560 1 792 112 1 792 5 760 4 800 TRAFFIC STUDIES MANUAL Page 14 March 9 2011 Table 3 2 ADT Volumes above which MUTCD Signal Warrants are Likely to Met Vehicles Per Hour on Number of Lanes for Vehicles Per Hour on Higher Volume Minor Moving Traffic on Major Street Total of Street Approach One Each Approach Both Approaches Equivalent ADT Direction Only Equivalent ADT Came amm warrant 1 600 42 4600 3220 condition a f 2 or more 1
147. in it will ultimately be required for the study In fact certain elements should not be collected until others have been reviewed For example hourly approach volumes preferably fifteen minute volumes should be counted for analysis of traffic signal warrants which is generally necessary for each of the three areas of concern Once the warrant analysis has been completed and the problem s has been identified and before any turning volumes are counted the machine counts should also be examined carefully to determine the control periods of interest These periods of interest are the peak and off peak periods for which the various signal operation plans will be designed DATA COLLECTION REDUCTION AND SUMMARIZATION Conducting the previously mentioned studies generates a large volume of data The study sheets and techniques available in this manual are designed to allow for use as field collection sheets reduction sheets and summary sheets thus reducing the amount of paperwork and time required to finalize field work A convenient manner in which to summarize and thus facilitate interpretation of the data required for the MUTCD signal warrants is to complete the Traffic Signal Warrants worksheet Form TR 01 in Chapter 3 For more information regarding data collection reduction and summarization see the individual chapters contained herein TRAFFIC STUDIES MANUAL Page 5 March 9 2011 2 6 1 2 3 4 5 6 2 7 1
148. in traffic which will permit an 85th percentile group of pedestrians to cross a roadway of specified width from a point of relative safety on one side to a point of relative safety on the other side without a vehicle crossing their path To determine the impacts of traffic on the calculated minimum adequate gap time the vehicle gap size should be analyzed as shown in the available gap survey portion of the pedestrian gap study form see Figure 9 1 The results of both pedestrian group size survey and available gap survey see Section 9 5 will determine if controls are warranted TRAFFIC STUDIES MANUAL Page 50 March 9 2011 Figure 9 1 Example of Pedestrian Gap Study Form FORM TR 12 WYOMING DEPARTMENT OF TRANSPORTATION REV 9 17 2010 PEDESTRIAN GAP STUDY PEDESTRIAN GROUP SIZE SURVEY LOCATION Main St amp D St CITY Dubois OBSERVER JU CROSSWALK ACROSS Main St CURB TO CURB DISTANCE W 60 ft RAISED MEDIAN No WIDTH OF MEDIAN N A ft REMARKS GROUP NO OF ROWS NUMBER OF GROUPS CUMULATIVE nem TALLY TOTAL TOTAL 3 or less if if Ji 27 nta ns 2 4 1 1 9 10 12 16 18 19 21 22 24 25 27 21 30 suk I I Cu cn O ee foo po o EM Total Number of Groups 0 85 26 4 MINIMUM ACCEPTABLE G W S 2 N 1 3 60 3 2 1 3 seconds AVAILABLE GAP SURVEY DATE 4 31 10 TIME FRO
149. irly high and the traffic control signals are visible for some distance in advance of the intersection 3 Even if it is not possible to identify platoon at a downstream intersection it 15 desirable to attempt to coordinate signalized intersections whenever possible 10 10 USE OF FLASHING OPERATION 1 There are number of situatlons when 1t may be appropriate to operate a traffic signal in the flashing mode Both pretimed and actuated signals may be operated in the flashing mode common use of planned flashing operation 1s at night or other times during periods of low traffic volumes Flashing operation based on low traffic volumes typically occurs on a daily or repetitive basis Operating a traffic control signal in the flashing mode when traffic volumes are low offers a number of potential benefits to the agency and to motorists including a Reduced stops and delay to major street traffic TRAFFIC STUDIES MANUAL Page 64 March 9 2011 b Reduced delay to cross street traffic c Reduction in fuel consumption due to the reduced delay d Reduction electrical consumption by the traffic control sienal equipment 2 When operated in flashing mode flashing yellow indications should be used for the major street J and flashing red indications should be used for minor street provided that minor street drivers have an adequate view of approaching major street traffic 3 All red flashing operation may be appropriate at m
150. istances and record observations Perform sight distance analysis 62 INTERSECTION SIGHT DISTANCE 1 The driver of a vehicle approaching or departing from an intersection should have an unobstructed view of the intersection including any traffic control devices and sufficient lengths along the intersecting highway to permit the driver to anticipate and avoid potential collisions Maze and Plazak 2000 These unobstructed views form triangular areas known as sight triangles 2 A typical intersection 1s divided into areas between each leg known as quadrants Sight triangles are the specified areas along an intersection s approach legs and across the included corners see Figures 6 1 and 6 2 for an illustration These areas should be clear of obstructions that might block a driver s view of conflicting vehicles or pedestrians The two types of sight triangles are approach sight triangles and departure sight triangles AASHTO Green Book 2004 6 2 1 APPROACH SIGHT TRIANGLES Approach sight triangles provide the driver of a vehicle approaching an intersection an unobstructed view of any conflicting vehicles or pedestrians These triangular areas should be large enough that drivers can see approaching vehicles and pedestrians in sufficient time to slow or stop and avoid a crash Approach sight triangles are illustrated in Figure 6 1 Figure 6 1 Approach Sight Triangles inor _ Major Street Source
151. isting or future Traffic Satisfy Signal Installation Warrants ___ _ 4 Did Any Special Reasons Justify Signal Installation sss Are These Reasons Still Valid 1 aia Comments Unknown Signal will need to be upgraded if left in place IF ANY OF THE ABOVE QUESTIONS ARE ANSWERED YES DEFER SIGNAL REMOVAL OTHERWISE PROCEED WITH DETAILED ANALYSIS TRAFFIC STUDIES MANUAL Page 127 March 9 2011 Figure 16 4 Example Signal Removal Analysis Worksheet Page 2 of 2 SIGNAL REMOVAL ANALYSIS WORKSHEET Stage 3 Detailed Analysis Two Way Stop Control 3 Estimated Impacts on Crashes To al Major Strcet Highcr Volume Side volume street Approach Minimum Check if Required J Minimum Table 16 1 Satisfied Crash Experience otal Crashes 14 Period Covered From 01 1997 To 12 2001 MM YYYY Volume Length of Time Period SUU years Average Annual 28 Crash requency X i From Equation 15 1 Y 1 01 0 139 0 605 Predicted Change in 0 5 Annual Crash Frequency Y Nin H ghest Hour Impacts Worksh Impacts Wor Annual Change From Impacts Worksheet From Impacts Worksheet al Chang Icling Delay Tota Delay Tota Stops Excess Fuel 3 3 Junction Related Cost Impacts Annual Signal Operation Costs Cos s Of Signal Removal Annual Costs Electrical 250 00 Remove Hardware 5 000 00 0142 710 00 Maintenance 91 700 00
152. ith a curve in the approach line representing the beginning of the path the vehicle would have followed if turning If a pedestrian is struck the general location by crosswalk and direction of travel should be diagrammed Similarly a fixed object crash should be shown in the correct quadrant of the intersection 73 CRASH LISTING 1 The crash listing is a detailed summary of the crash Information represented in the collision diagram Figure 7 2 15 an example of a crash listing Crash listings are typically generated by Intersection Magic for the referenced intersection 2 In reviewing the summary of the crash information the following factors are important The day of the week can be significant because certain parking and turning restrictions may apply only on weekends The date is necessary to allow the separation of crashes which may have occurred before or after a change in control improvement or increased traffic volume The time of occurrence is important for developing crash rates as a function of traffic volume during certain time periods for performing violation or other observance studies and for possibly limiting applications of certain regulations during specific hours of the day TRAFFIC STUDIES MANUAL Page 43 March 9 2011 Sheridan W Y 38 Accidcnts Figure 7 1 Example Collision Diagram J8 lt 5 18 Ye We o ES 8 8 8 0718491 200912365 gt 0707685 ala
153. ith other US numbered routes d Rural intersections with raised channelization 15 2 1 CONTINUOUS FREEWAY LIGHTING Case CF L I Continuous freeway lighting is considered to be warranted on those sections and near cities where the current ADT both directions is 30 000 or more Case CF L 2 Continuous freeway lighting is considered to be warranted on those sections where three or more successive interchanges are located with an average spacing of 1 miles or less and adjacent areas outside the right of way are substantially urban in character TRAFFIC STUDIES MANUAL Page 105 March 9 2011 Case CFL 3 Continuous freeway lighting is considered to be warranted where for a length of 2 miles or more the freeway passes through a substantially developed suburban or urban area in which one or more of the following conditions exist a Local traffic operates on a complete street grid having some form of street lighting parts of which are visible from the freeway b The freeway passes through a series of developments such as residential commercial industrial and civic areas colleges parks terminals etc which includes roads streets and parking areas yards etc that are lighted c Separate cross streets both with and without connecting ramps occur with an average spacing of 1 2 mile or less some of which are lighted as part of the local street system d The freeway cross section elements such as median and borders
154. l as both directions at once If the speed study 15 checking speeds by vehicle classification the Speed Study Worksheet can only process one vehicle class at a time The class of vehicle being studied should be noted in the Comments space of the input sheet Once all of the necessary data 1s entered on the input sheet the speed study statistics can be viewed by selecting one of the display sheets Figure 13 4 gives an example of the Speed Study Worksheet output for one direction of travel For a neat computer generated sheet that duplicates the hand written data from the data collection sheet the cleaned field data sheet uses the same data entered on the input sheet to provide a copy of the Speed Data Collection Sheet with the heading data and tally marks filled to match the form completed by hand Figure 13 5 gives an example of the cleaned field data collection sheet TRAFFIC STUDIES MANUAL Page 89 March 9 2011 Figure 13 3 Example Speed Study Worksheet Data Input CITY Ranchester COUNTY Sheridan ROUTE US 14 Dayton 51 LOCATION At4th WW POSTED SPEED LIMIT 40 OWEST SP ED RECORDED 30 HIGHESI SPEED COMMENTS DIRECTION 1 DIRECTIOM 2 Westbound OBSERVER LOT OBSERVER JD T CATE 8190 DATE 5 1910 START TIME 8 40 START TIME 9 55 AM END TIME 9 50 AM END TIME 10 45 WEATIER Clear amp Warm WEATHER Clear amp Warm NUMBER OF OBSERVATIONS AT SPEED PER DIRECTION S
155. l axis and read the estimated value of the impact variable for the example the results are 1 4 3 1 390 and 2 6 Enter these values in their respective columns on the worksheet on line 3a b Estimate the four impact variables for two way stop control Use the same nomographs in the same manner as Step 3a but for total main road volume use the family of lines representing two way stop control the dotted lines Enter the estimates on the worksheet on line 3b for the example the results are 0 2 0 7 110 and 0 6 Nomographs for the example worksheet are shown in Figures 16 6 and 16 7 Note The user should not attempt to estimate values from the nomographs to any closer precision than 2 significant digits Graphical interpolation can be no more precise c For each of the four impact variables the difference between the signal control and two way stop control estimates 1s calculated 1 e the 3b entries are subtracted from the 3a entries The impacts for the total of the 2 peak hours are then calculated a The total intersection approach volume for the total of the 2 peak hours 1s calculated 1 the entry on line 2c is multiplied by 2 b The signal removal impacts for the total of the 2 peak hours 15 calculated 1 e each of the four impact variables entered on line 3c are multiplied by 2 Enter the traffic volumes for the average of the 22 remaining hours of the day a For the main road calculate the average total
156. lane warrants rural two lane highways These criteria are dependent on the volumes of traffic entering the intersection during the peak hour and the approach speed on the approach opposing the left turn movement and are shown in Figure 18 1 To use the figure peak hour traffic counts including directional splits will be required see Chapter 4 In addition the ITE Trip Generation Manual may be used as an estimate for peak hour traffic counts when new or modified development is involved The Planning Program can provide necessary growth rates for design year analysis The appropriate trend line 1s identified on the basis of the percentage of left turns in the advancing volume rounded up to the nearest percentage trend line If the advancing and opposing volume combination intersects above or to the right of this trend line a left turn lane can be considered appropriate Since the construction of auxiliary left turn lanes requires pavement marking that effectively eliminate passing opportunities for a substantial distance constructing auxiliary left turn lanes for volumes that do not meet the 50 AASHTO criteria should be avoided unless a crash problem has been identified at that location TRAFFIC STUDIES MANUAL Page 147 March 9 2011 3 Left turn lanes typically not needed for left turn volumes of less than 10 vph However criteria other than volume such as crash experience may be used to justify a left turn lane Figure 18 1 Gu
157. le levels of lateral acceleration TRAFFIC STUDIES MANUAL Page 69 March 9 2011 11 2 USE OF THE DESIGN SPEED EQUATION 1 2 3 4 The design of highway curves is based the relationship between design speed radius of curvature superelevation and side friction centripetal acceleration The design speed equation can be used to calculate the advisory speed for a curve if the curve radius and superelevation are known The side friction factor is the same as lateral acceleration measured in g s and is based on driver comfort For the establishment of advisory speeds on curves the lateral acceleration rates contained in Table 11 1should be used The mathematical relationship between these variables 1s given by the equation Equation 11 1 V 415R 0 01e f Where V Design speed mph R Curveradius feet e Superelevation 90 f Side friction factor The rounded advisory speeds calculated for various combinations of superelevation and curve radius are shown in Table 11 2 Table 11 2 Rounded Passenger Car Advisory Speeds mph Superelevation Radius ft 100 200 Based on Design Speed Equation and Table 11 2 Side Friction Factors In some cases the curve radius and superelevation can be taken from as built plans for a roadway that has been constructed fairly recently However it must be considered that a roadway that has been in service for many years may have been resurfaced one
158. leted fairly quickly based on existing intersection data The purpose of this quick screening is to determine if additional analysis of the intersection is justified Figure 16 1 gives an example of the preliminary Stage 1 signal removal decision process in the form of a flowchart TRAFFIC STUDIES MANUAL Page 109 March 9 2011 Figure 16 1 Signal Removal Decision Process Stage 1 Preliminary Screening Inventory of current conditions side street sight distance adequate for safe gap acceptance Do special site conditions make removal institutionally nfeasible No Forecast traffic volume levels to intermediate future i e 5 yrs Does existing or future traffic satisfy any of the signal installation warrants If reasons other than Yes standard warrants justified installation o these reasons still prevail NO Op ional Crash record No significart better with Compare crash change in crash signal frequency and record severity before and after signal installation if data is available Crash record worse with signal or no data d MEA or Mo signal removal signal removal analysis analysis including signa removal STAGE 2 TRAFFIC STUDIES MANUAL Page 110 March 9 2011 3 4 5 The intersection data required to perform signal removal analysis are basic specifically a Side street sight distance b The traffic v
159. little delay In this case the approach should be considered a single lane approach but the right turn volumes from the minor street should not be included in the warrant analysis TRAFFIC STUDIES MANUAL Page 12 March 9 2011 5 6 3 5 1 2 3 4 5 6 7 9 Minor street approaches having a single left turn through lane and a free flow right turn lane should be considered a single lane approach and the right turn volumes from the minor street should not be included in the warrant analysis Major street approaches having single through lanes with separate left or right turn lanes typically considered one lane approaches for the warrant analysis VOLUMES The volumes of traffic used in a full signal warrant analysis should be the actual turning movement count see Chapter 4 taken for the highest 8 to 12 hours in an average day a weekday representing traffic volumes normally and repeatedly found at the location A review of the latest machine counts should be conducted first In order to determine a The need for a turning movement count 1 e if the volumes are too low then 8 to 12 hours of manual count are not needed and the warrant analysis may be completed based on the machine counts only and b The appropriate time periods for conducting the turning movement count In all of the warrants where hourly volumes are to be entered any hourly period may begin on any quarter hour 7 15
160. lps investigate the need for changes to existing traffic control devices The diagram should also be part of an intersection crash analysis COMPLETING THE CONDITION DIAGRAM The location information should be entered so that the intersection is thoroughly identified The state U S or county route numbers and street names for both streets should be included if applicable as well as the County City Date and Person s preparing the diagram Orient the intersection by indicating north with a north arrow items associated with the streets should be drawn using representative symbols The diagram should also include the width and surface type of the streets the grades if 5 percent more and traffic control devices All measurements should be as accurate as possible and indicated on the diagram The usual distance measured from the intersection 15 80 to 100 feet however In those cases where pertinent signing or pavement markings concerning the intersection such as Stop Ahead occur in advance of the intersection in question those conditions should be diagrammed and distances indicated with a broken arrow Reasonable judgment should be used to decide the distance away from the intersection to include elements in the condition diagram Show all lanes and the movements allowed required from each lane Include lane widths full width turn bay lengths and turn bay taper lengths Note the posted speed limit on all approaches and
161. lume would be studied since that approach would likely have the longest delays and would experience the greatest overall delay One or two lanes can be measured at once If the study is interested in knowing the queue lengths or specific details about the length of delay experienced by individual vehicles then delays on each lane of the approach must be measured separately If the study is being used only to determine the average stopped delay for the entire approach not necessarily by lane and the reviewer is not necessarily concerned with vehicle queues multiple lanes can be measured simultaneously by using only one set of stop and buttons on the board This method will not accurately measure queues or individual vehicle delays but can be used as a quick check to determine total approach delay and average delay per vehicle for the entire approach Using this method allows the data collector to also measure the total stopped delay and average stopped delay per vehicle on the opposing STOP controlled approach by using the second set of stop and eo buttons for the opposing approach TRAFFIC STUDIES MANUAL Page 47 March 9 2011 Figure 8 1 Example Stop Sign Delay Study Wyoming Department of Transportation Traffic Program Safety amp Studies Section Intersection Pine amp Tyler Cheyenne WY Counted By Auzqui amp Nelson Weather Comments Summary Information 00 00 PM 4 00 00 3 00 00 Ph
162. m required sight distance Compare the measured sight distance see Chapter 6 in each direction from each minor street approach to the suggested departure sight distance at intersections as shown in Table 16 4 If the measured sight distance is less than those shown in the table check YES next to line 1 and defer signal removal unless the sight obstructions can be easily remedied Table 16 4 Suggested Departure Sight Distance at Intersections Design Speed Minimum Departure Sight Distance Source AASHTO A Policy on Geometric Design of Streets and Highways 2004 Exhibit 9 55 2 Special site conditions Note whether or not any special site conditions exist per Section 16 2 2 If no special conditions exist check NO otherwise check YES and note in the comments field what those conditions are If you check YES initiate communication with representatives TRAFFIC STUDIES MANUAL Page 121 March 9 2011 from the affected facilities to assess the possible strength of opposition to or support for the possible signal removal before proceeding any further with the signal removal process 3 Existing signal warrants met This can be estimated by comparing the actual ADT s with the approximate ADT volumes above which MUTCD signal warrants are likely to be met see Table 3 2 on Page 15 If current or projected traffic volumes do not meet MUTCD signal warrants check NO If MUTCD signal warrants are met or projected to be met in the near fu
163. main road volume for the remaining 22 hours using the following method e Subtract the total of the 2 peak hours of the main road volumes from the major street ADT from Form TR 03 e Divide by 22 to get the average for the remaining 22 hours For the example use 9350 2 700 22 to get an average of 361 vehicles per hour for the total main road volume for the remaining 22 hours b For the side road the same basic process used for line 5 15 used except with the following modifications e Multiply the side road volume per approach by 2 to get the total average side road volume for the peak 2 hours e Multiply that by 2 again to get the total peak 2 hour side road volume e Subtract that total from the side street ADT from Form 03 and then divide by 22 to get the average total side road volume for the remaining 22 hours e Divide that by 2 to get the average side road volume per approach for each of the remaining 22 hours For the example use 1220 52x2x2 22 2 to get 23 as the average volume per approach for each of the remaining 22 hours In some instances the minor street ADT may not be known A reasonable estimate of the side road ADT can be determined by determining what proportion of the major street ADT 15 included in the turning movement count used for the analysis and then assuming the minor street volume constitutes the same proportion of the minor street ADT Using the turning movement count volumes the
164. mating Daily Impacts of Signal Removal and Replacement by Two Way Stops The main purpose of the worksheets is to determine if the removal of an existing unwarranted traffic signal can be accomplished without an increase in crashes and with improvements to intersection operations This process is only valid for intersections that are being converted from signalized control to two way stop control The Signal Removal Analysis Worksheet has been developed into a two page PDF form The first page covers the intersection inventory and preliminary screening and the second page covers the detailed analysis The detailed analysis also requires the completion of the Signal Removal Impacts worksheet which is also covered in these instructions STAGE 1 INTERSECTION INVENTORY Fill out the appropriate information as required 1 Identify the intersection and city 2 Indicate which street is the major street and which one is the minor street 3 Indicate the number of lanes per approach for each street 4 The ADT required is the two way average daily traffic volume 5 Note the posted speed limit on the major street 6 Note the side street sight distance for all side street approaches STAGE 2 PRELIMINARY SCREENING This 15 a quick screening to determine if additional analysis of the intersection is justified It is made up of the following four separate criteria each involving a go no go decision concerning signal removal 1 Minimu
165. me of the right turn traffic can proceed with little delay but some will be impeded by through or left turn traffic Also the presence of the right turn traffic though it may be able to turn with little delay adds delay to the through and left turn traffic In this case all of the left turn and through volume plus 50 of the right turn volume should be considered in the warrant analysis and the single lane approach criteria should be used TRAFFIC STUDIES MANUAL Page 13 March 9 2011 3 6 PRELIMINARY SCREENING 1 Prior to conducting a full traffic signal warrant analysis existing two way average daily traffic ADT volume data should be reviewed to determine if the intersection experiences enough traffic to possibly meet any traffic signal warrants The ADT volumes for all state highway routes are available the latest Vehicle Miles Book published by the Department s Planning Program each year The ADT volumes for most major city streets are also available from the Department s Planning Program Table 3 1 shows the minimum ADT volumes below which it 15 impossible to meet the 8 hour traffic signal warrant criteria 2 The Equivalent ADT volumes indicated in the table are the minimum hourly volumes required to meet the 8 hour warrant criteria multiplied by 8 the number of hours that must meet the minimum volume criteria If either street at the intersection experiences traffic volumes below the equivalent ADT for the applicable number of lan
166. mes and four impact variables are input from respective nomographs example worksheet for a 4 way intersection 4 lane major and 2 lane minor street is presented in Figure 16 5 1 2 3 Enter Intersection type 4 way or and number of lanes 2 4 on major road and minor road by clicking on the respective check boxes The number of lanes 16 defined as the total number of through lanes in both directions on a given road 4 lane means two through lanes in each direction Enter the traffic volumes for the average of the 2 peak hours of the day The following volumes were used for the example in Figure 10 5 a For the major road enter the total volume for the 2 approaches averaged for the 2 peak hours For example Main Road Spruce Street Example Eastbound Appr Westbound Appr Total Highest Hour 354 356 710 274 Highest Hour 342 347 689 Divide by 2 1399 Total main road volume per hour 700 vph b For the side road enter the average volume per approach for the 2 side road approaches averaged for the same 2 peak hours as above For example Side Road 7th Street Example Northbound Appr Southbound Appr Average Highest Hour 27 70 49 2 Highest Hour 18 90 54 Divide by 2 103 Total side road volume per hour per approach 52 vph For a T intersection simply average the volumes for the 2 peak hours on the only side road approach c The total intersection approach volume a
167. n Transport Roadway Seo improper Tum or No Signal STANY 336 West Stopped In Traffic Motor Vehicle In Transport an Roadway No improper Driving 05 26 0010 1058 211005552 H MAIN ST O Related Angle nat Speciiied South Turning Righk Motor Vehicle In Transport an Roadway Dxayllght Dry Improper Turn or No Signal STANY 3 30 South Turning Right Motor Vehicle In Transport on Roadway No improper Driving 1215 20 930 201018458 STH STAY 330 Intersection Related Rear End Front to Rear East Straight Ahead Motor Vehicle In Transpert on Roadway Daylight Wet Following too Close N MAIN ST East Slowing Motor Vehicle In Transport on Roadway No Improper Driving 011 011182211 asp 201100696 STHST Intersection Rear End Front to Rear South Turning Right Motor Vehicle In Transport Roadway Show Drove too Fast for Condition Al MAIN ST Viest Turning Let Motor Vehicle In Transport Roadway IcelFrost Ho improper Driving HUM BER HUMBER OTAL CRASHES IN THIS REPORT 12 PERSONS PERSONS PDO INJURY FATAL TOTAL CRASHES CRASHES CRASHES CRASHES INJU RED KILLED NJURY CRASHES 2 6 2 D ATAL CRASHES 2009 2010 1 3 0 0 3 TOTAL PERSONS INJURED TOTAL PERSONS KILLED TOTAL 2 3 2 11 PDO Property Damage Only Crashes Injuries Mo Fatalities TRAFFIC STUDIES MANUAL Page 46 March 9 2011 8 1 CHAPTER 8 STOP SIGN DELAY STUDY PURPOSE The stop
168. nals will fluctuate with traffic demands while the duration of all phases of fully actuated signals will fluctuate with traffic demands Pretimed traffic signals are cheaper to install and maintain but are relatively inefficient where traffic volumes fluctuate widely and irregularly Actuated signals are generally more expensive to install and maintain but are more efficient because they can respond to greater variations in traffic The reduction in motor vehicle operating costs and possible reduction in crashes associated with more efficient traffic signal operations will normally offset the added installation and maintenance costs associated with maximizing the efficiency of the intersection controls Overall there are valid considerations for using each of the various control types TRAFFIC STUDIES MANUAL Page 62 March 9 2011 Figure 10 1 Measuring Pedestrian Crosswalk Lengths FEE L Trafiprelim d DATE 10 08 14 10 AC a Be eo To measure the length of crosswalk start at the center of the curb ramp and proceed to the opposite curb ramp as indicated by the arrows If there are no ramps or crosswalks note the lack thereof then follow the anticipated pedestrian crossing route to establish the measurement _ ja aar E eben No parking lane or turn lane measure to projected parallel edge line or lip o
169. nditions are detailed in Section 4C 06 of the MUTCD Before a decision is made to install a traffic control signal consideration shall be given to the implementation of other remedial measures such as warning signs and flashers school speed zones school crossing guards or a grade separated crossing 3 13 WARRANT 6 COORDINATED SIGNAL SYSTEM Progressive movement in a coordinated signal system sometimes necessitates installing traffic signal at intersections where they would not otherwise be needed in order to maintain proper platooning of vehicles The warrant conditions for this warrant are detailed in Section 4C 07 of the MUTCD In order for this warrant to apply there must be a signalized intersection more than 1 000 feet away in each direction along the coordinated signal corridor TRAFFIC STUDIES MANUAL Page 28 March 9 2011 3 14 WARRANT 7 CRASH EXPERIENCE The Crash Experience signal warrant conditions are intended for applications where the severity and frequency of crashes are the principal reasons to consider installing a traffic control signal The warrant conditions for this warrant are detailed in Section 4C 08 of the MUTCD 3 15 WARRANT 6 ROADWAY NETWORK Installing a traffic signal at some intersections might be justified to encourage concentration and organization of traffic flow on a roadway network The warrant conditions for this warrant are detailed in Section 4C 09 of the MUTCD 3 16 WARRANT 9 INTERSECTION NEAR
170. ng conditions and speeds may vary widely from time to time No posted speed limit can adequately serve all driving conditions Motorists must constantly adjust their driving behavior to fit the conditions they encounter Any speed limit other than a statutory speed limit listed above that is posted on the Wyoming state highway system must be based on an engineering study That study must include an analysis of free flow traffic speeds A Spot Speed Study is used to measure the free flowing traffic speed characteristics at a specified location under the traffic and environmental conditions prevailing at the time of the study Spot speed data 15 also used in various other traffic engineering activities such as determining traffic signal timings establishing highway design elements analyzing roadway capacity and evaluating the effectiveness of improvements The purpose of this chapter is to establish the proper study procedures for completing the engineering and traffic investigation in accordance with the statutes to provide guidance in setting appropriate speed limits based on the study data and to establish the documentation and notification procedures when establishing new speed limits SPEED STUDY DATA COLLECTION The basics of spot speed study data collection such as site selection sample size requirements and the selection of target vehicles are described in the ITE Manual of Transportation Engineering Studies For most spot speed studie
171. ng drivers and create inconsistencies that may lead drivers into traveling at too high a speed through other curves In some cases there may be other factors that influence the selection of the advisory speed in addition to the comfortable operating speed on the curve Available stopping sight distance through the curve and sight distance from intersections or driveways within the curve see Chapter 6 or deceleration distance on an exit ramp may in some cases require an advisory speed somewhat lower than the comfortable operating speed for the curve Each direction should be checked independently and may be posted with different speeds Advisory speed plaques should be used in conjunction with curve and turn signs when the advisory speed 15 below the posted speed limit on the roadway Advisory speed plaques are only used in conjunction with appropriate warning signs and never alone Turn Curve Reverse Turn Reverse Curve and Winding Road signs are used in locations where it is desirable to warn drivers of changes in the horizontal alignment of the roadway The MUTCD indicates that the use of Turn or Reverse Turn signs should be limited to changes in alignment where the advisory speed is 30 mph or less The Curve or Reverse Curve signs are intended for use where the advisory speed 15 greater than 30 mph Where a Reverse Curve warning sign or a Winding Road warning sign 15 used the advisory speed should be based on the curve with the lowest
172. ng the public notification process which is discussed in Section 16 5 1 TRAFFIC STUDIES MANUAL Page 117 March 9 2011 16 3 5 SIGNAL REMOVAL DECISION 1 2 of the above findings are then weighed by the traffic engineer and the decision 1s made whether or not to recommend removal of the traffic signal It is neither possible nor desirable to avoid a significant amount of professional judgment in this final decision In most cases a number of institutional constraints must also be considered However the technical findings from the detailed analysis should provide a strong factual basis for reaching supporting and defending the final decision or recommendation of the findings of the decision process should be summarized by the traffic engineer in a signal removal justification report for use in gaining necessary authorization to proceed 16 4 INTERSECTION CONTROL ALTERNATIVES There are three alternatives to signalized intersection control two way stop control all way stop control or roundabout control Each has its own operational strengths and limitations in comparison with traffic signal control and the appropriate alternative control is dependent on the conditions present at the intersection Each alternative will be discussed separately 16 4 1 TWO WAY STOP CONTROL TWSC 1 2 TWSC accommodate low traffic volumes with much less delay than traffic signals but this type of control favors the major
173. nges of costs contained in Table 16 2 These costs are then totaled automatically by the form Estimate the one time costs of signal removal and STOP sign installation and enter these costs into their respective fields 1 e Remove Hardware and Install Stop Signs on Form TR 03 If the specific costs are not readily available reasonable estimates should be made using the ranges of costs contained In Table 16 3 These costs are then converted to equivalent annual costs by multiplying them by 0 149 the capital recovery factor assuming 15 years at 12 interest Enter the estimated annual sign maintenance costs The total annualized cost of signal removal is then computed by the form by adding this and the previous costs The difference between the annual costs of operation and the annual removal costs is the annual cost savings from signal removal Note If the result for the annual cost savings from signal removal is negative that implies that the removal of the signal could actually cost more than its continued operation Although possible that 15 a very rare occurrence and the estimated costs of both continued operation and removal should be rechecked to verify that the continued operation costs are not underestimated and or the removal costs are not overestimated TRAFFIC STUDIES MANUAL Page 125 March 9 2011 STAGE 3 4 ANTICIPATED STRENGTH OPPOSITION SUPPORT FOR SIGNAL REMOVAL By this time the traffic engineer should have been
174. no longer be seen The point where the target rod disappears 1s the maximum sight distance along that leg The position should be marked and the distance to the intersection should be measured along the centerline of the roadway The analysis of intersection sight distance consists of comparing the recommended sight distance to the measured available sight distance The comparison of the actual distances should be performed with consideration to posted speed limit If the measured sight distance is less than the recommended sight distance some mitigation may be required Some mitigation measures are as follows a Remove modify obstruction b Post a reduced advisory speed c Install additional traffic control devices if warranted by the MUTCD STOPPING SIGHT DISTANCE The available sight distance on a roadway should be sufficiently long to enable a vehicle traveling at the posted speed to stop before reaching a stationary object In its path Although greater lengths of visible roadway are desirable the sight distance at every point along a roadway should be at least that needed for a below average driver or vehicle to stop AASHTO Green Book Stopping sight distance is defined as the sum of two distances a Brake reaction distance the distance traveled by the vehicle from the instant the driver sees an object necessitating a stop to the instant the brakes are applied plus b Braking distance the distance needed to stop the v
175. nt to the traffic engineer guide for conducting comprehensive traffic signal studies The information techniques and instructions presented herein were formulated from the MUTCD and experiences of practicing traffic engineers 2 This manual is not all inclusive in addressing traffic signal study situations rather it is a general guide for the traffic engineer to follow while investigating conditions and circumstances regarding the installation of a new traffic signal or improvement of the operation of an existing traffic signal This manual will begin with an alleged problem concerning traffic control at a particular location The observation of the symptoms establishment of areas of concern collection and analysis of data and preparation of a traffic signal study report will be outlined in subsequent chapters 3 This chapter provides a logical and systematic data collection procedure for investigating traffic signal requirements which allows the traffic engineer to use judgment to analyze local conditions and interpret data as effectively and efficiently as possible with the resources available By following this chapter it 15 intended to minimize the collection of unnecessary or inappropriate data and or to reduce the number of trips to the field to collect additional data 22 LEARNING OF THE CONCERN 1 The problem facing traffic engineers at this point has yet to be defined This is the stage during which the traffic engineer receive
176. nterval Length From Data First Interval 15 00 2 25 Last Interval f 15 Minutes E 1 15 45 2 25 t Minutes f Grand Total Options Print Comments Empty Intervals Print Peaks lw Hide Empty Intervals Intersection Drawing Wording Intersection Photo Es Ez s s Do Print Headings Hide Header Information Preview Print Save Print Defaults Close Help The total number of gaps of each size from the combined groups of the multi direction study can then be entered directly into the Total column in the available gap survey portion of the pedestrian gap study form The stop sign delay study procedure can be adapted to measure and document the length of each gap over an extended period of time This is accomplished by marking the beginning of each gap in traffic by pushing the Vehicle Stops button and then pushing the Vehicle Goes button at the end of the gap This effectively documents the time and duration of each gap measured The stop sign delay study procedure is detailed in the respective user s manual for the TDC 8 or TDC 12 When stop sign delay study used for measuring gaps is processed through the PetraPro analysis software the individual gaps can be displayed printed and or exported to a spreadsheet for transfer to the available gap survey portion of the pedestrian gap study form To print the study displaying the individual gap
177. nual The calibration constant should be recorded on the PC Travel Field Worksheet 5 Prepare the TDC 8 for a travel time TT study following the procedure described the 8 User s Manual 6 Start a run by driving to the starting point so that when you pass the starting point you are traveling at the proper speed with the rest of the traffic Press the DO button on the TDC 8 as accurately as you can as you pass the starting point this begins data collection The display shows the run number link number how many times you have pressed the New Link button this run time distance traveled so far this run speed as well as the last delay button pushed the L Key value As you proceed along the route press the New Link button as you pass each new section Note Check the speed reading on the TDC 8 and make sure it is close to the speed on the speedometer If they are not reasonably close within a few miles per hour it may indicate a problem with the sensor or an incorrect Calibration Constant Don t collect data if the speed isn t right the data almost certainly won t be correct TRAFFIC STUDIES MANUAL Page 101 March 9 2011 7 9 9 10 14 5 1 2 3 4 Note If you have chosen intersections as your nodes wait until you exit intersection to press the New Link button This will ensure that any delay associated with stops at the intersection will be reported in the correct section
178. o much time lapses before implementation it may be necessary to repeat the entire traffic signal study procedure For this reason it is wise to plan traffic signal studies in close conjunction with the State Transportation Improvement Program STIP If this is not done the result may be an improvement that does not match the conditions at the site Following implementation the engineer should always visit the site to determine if the traffic signal is operating as designed As a minimum he should observe the operation during each critical time period keeping in mind the original concern and or any other concerns identified the Traffic Signal Study Report It is always a good idea to drive through the intersection from all approaches and to make any critical turning maneuvers The Operational Review Signalized Intersection Checklist Form TR 18 provides a convenient form on which to check each of the signal components and note any concerns or deficiencies see Chapter 10 In some cases data collection may be necessary to determine if and how well the improvement is operating This 15 particularly true for the after condition of a before and after study where crash data Chapter 7 travel time and delay data Chapter 14 etc are required It 15 also advisable to follow through on the implementation of a traffic signal with an educational program preferably before any ground 15 broken to increase public awareness of the change This shoul
179. od This may require the development of a close liaison between the traffic engineer and local police department s crash records division in order to obtain copies of the crash reports shortly after any crashes might occur An increase in crashes particularly if they are right angle or involve injuries during the first critical month is not a sufficient reason to abandon the plans for removing the signal Although if an increase does occur the signal should remain in the transition control mode for a few more months If the crash rate is still higher after a few months an in depth crash analysis should be performed and retention of the signal should be seriously considered Accurate crash records should be kept on the intersections in the jurisdiction where the signal has been removed for several years following the signal removal Assuming that there will be a decrease in crashes at most of these intersections this kind of positive information which is based on intersections within the jurisdiction itself not only lends credibility to the local signal removal but also sets the valuable precedent for additional signal removals TRAFFIC STUDIES MANUAL Page 120 March 9 2011 INSTRUCTIONS for the Wyominzg Department of Transportation SIGNAL REMOVAL ANALYSIS WORKSHEETS USING THESE INSTRUCTIONS The purpose of these instructions is to assist WYDOT personnel in completing the Signal Removal Analysis Worksheet and the Worksheet for Esti
180. of minimum adequate gap measuring the gap sizes in the traffic stream and determining the sufficiency of adequate gaps The principal application of the study results 1s 1n analyzing roadway crossings by pedestrians to determine appropriate traffic controls and safety improvements The results of gap studies are used in pedestrian and school crossing studies and in traffic signal warrant analyses PEDESTRIAN GAP STUDY FORM The Pedestrian Gap Study form Form TR 12 is used to determine the pedestrian group size minimum adequate gap length and to determine the frequency and duration of adequate gaps available at the crossing location A blank form can be printed for use in the field to gather the data and then the PDF form can be completed in house for a clean presentation of the data and calculations In order to accurately analyze the data the top portion of the Pedestrian Gap Study form should be filled in as completely as possible Enter the location so that the study location is thoroughly identified The U S route numbers state route numbers and county road or street names should be included if applicable Enter the county city date time of study and the observer making the study Identify the street associated with the crosswalk Enter the width of the street from edge to edge or from curb to curb If the roadway has a raised median indicate by circling YES if not circle NO If divided indicate the width of the median Also
181. of the 22 hours 15 calculate 1 e the entry on line 5c is multiplied by 22 b The signal removal impacts for the total of the 22 hours are calculated 1 each of the entries on line 6c are multiplied by 22 The 24 hour total impacts are calculated a The 24 hour total intersection approach volume 15 calculated 1 e line 4a and line 7a are added together b The signal removal impacts for the total of 24 hours are calculated 1 e the 4b entries and the 7b entries are summed for each of the four impact variables The per vehicle impacts are calculated by dividing the 24 hour total impacts on line 8b by the 24 hour total volume on line 8a In the case of idling delays per vehicle delays are converted from hours to seconds by multiplying by 3600 Enter the estimated per vehicle and daily changes in idling delay total delay total stops and excess fuel consumption line 8b entries on the impacts worksheet see Page 129 into the respective traffic flow related impacts fields on Form TR 03 Multiplying the daily values by 320 will provide the estimated expected annual change STAGE 3 3 JURISDICTION RELATED COSTS 1 2 3 4 Enter annual electrical maintenance and timing costs associated with continued signal operation If available these costs should be the actual costs for the intersection in question If the specific costs are not readily available reasonable estimates should be made using the ra
182. oints 1 000 or more 5 points Less than 1 000 points Minor Road Daily Volume Highest two way volume Minor 1 600 10 1 000 or more 10 points 500 vpd or more 5 points Less than 500 vpd points Night Minor Road Hourly Volume 5 00 pm to 6 00 am Minor 240 0 250 vph or more 10 points Less than 250 vph points CRITERIA 4 CRASH EXPERIENCE Number of night crashes in past five years Number 3 X5 15 Ratio of night to day crashes Ratio 0 25 0 2 0 more 10 points 1 0 or more 9 points Less than 1 0 points TOTAL POINTS 62 Minimum of 50 points required for consideration of intersection lighting TRAFFIC STUDIES MANUAL Page 108 March 9 2011 16 1 1 2 3 4 5 16 2 1 2 CHAPTER 16 TRAFFIC SIGNAL REMOVAL STUDY PURPOSE No matter what reason was used to justify a traffic signal installation changes over time may reduce the need for and effectiveness of the traffic signal When this occurs problems created by unwarranted signals such as excessive delay increased rerouting of traffic to less appropriate roads and intersections higher crash rates and disobedience of the traffic signal can often be addressed by removing the signal 1f doing so would not create worse problems The MUTCD contains no specific warrants for the removal of traffic signals The only guidance relative to signal removal is a statement Section 4B 02 that states If changes in traffic
183. olumes entering the intersection in each hour during a representative day c The crash history at the intersection for at least three and preferably five or more preceding years Depending on site specific conditions additional data such as major street speeds heavy turning movements pedestrian counts etc may also be necessary After the intersection data 1s obtained a series of criteria are considered each of which must be satisfied In order for the intersection to survive the screening 16 2 1 SIGHT DISTANCE 1 2 3 The sight distance available to the side street particularly if two way stop control is proposed is very important to the removal decision If the sight distance available for the side street is less than the stopping sight distance for the mainline approach speed signal removal should not be further considered unless the sight restriction can be reasonably mitigated Removing a traffic signal at an intersection without adequate sight distance will more than likely double the number of expected right angle crashes when compared to intersections with adequate sight distance The sight distance should be measured in each direction from each minor street approach in accordance with Chapter 6 The line of sight should be from the driver s eye position where traffic would normally be expected to stop and look for gaps in approaching traffic if the intersection were stop controlled If limited sight distance is c
184. on a particular run or you simply don t need node by node statistics for this route You can define a run as Secondary and any node distance data in the run will be ignored in the analysis A collection of runs When the user collects data he is making data runs and when he gets back to the office he collects those runs into studies The difference 15 important because runs can be collected into different studies For example a user may make a number of runs at an arterial during one or two days Back in the office he may create a study with just the morning runs He may also create a study with all of the runs which of course use some of the morning runs There is one critical rule for studies of the runs in a study must start at the same place end at the same place and follow the same route Only runs in the same direction can be part of the same study Since you usually collect runs in two directions up and back you will typically create at least two studies for each data collection session TRAFFIC STUDIES MANUAL Page 98 March 9 2011 Study Group A folder where related runs and studies are stored Since studies must be created from runs that start in the same place end in the same place and go in the same direction it makes sense to store all runs that fit those criteria in one place on computer along with any studies that are created from those runs Since at least two sets of runs are usually collected one in one dire
185. on enhancements 14 2 DEFINITIONS Average Speed The total distance covered divided by the elapsed time average speed for each section node to node distance and a total average speed for the entire route are calculated separately Before and After A way to categorize a group of runs so that two different groups of runs can be compared terms Before and After mean only that the data is summarized into two separate groups so the statistics of each group can be compared If all of one set of runs are made under the same conditions they may all be defined as before runs Later identical runs made under different conditions after an arterial has been re timed for example may be defined as after runs The analysis can then compare statistics for the before runs as a group the after runs as a group and changes in the various statistics from before to after Fixed Route Data collection along a pre determined route When doing fixed route studies run data is collected along the same route several times One run is rarely sufficient to find the travel time characteristics of a route The operator may never hit a red light during a run or may hit several If several runs are collected the averages of the individual run data will be a better representation of the true traffic characteristics of the route Fixed route studies usually have segments defined at the time the runs are made The route is divided into geographic segments
186. one shown in Table 12 3 If the no passing zone length exceeds the maximum sight distance restriction listed in Table 12 3 the no passing zone will be marked No passing zones installed under this condition are extended to a length of 500 feet with the additional length added to the beginning of the no passing zone The DMI reading for the new TRAFFIC STUDIES MANUAL Page 81 March 9 2011 6 7 8 9 12 5 1 beginning point for the no passing zone is marked on the printout so the pavement can be marked in advance of the actual point where the sight restriction begins If the length of no passing zone is less than the distance shown in Table 12 3 then conditions in either direction beyond the sight restriction are evaluated to determine whether or not the area should be marked as a no passing zone If the situation causing the brief sight restriction doesn t warrant a no passing zone the section will not be marked as a no passing zone If the conditions do warrant a no passing zone its length will be increased to 500 feet as in the previous paragraph Table 12 3 Maximum Sight Distance Restriction to Allow Omission of No passing Zone POSTED MAXIMUM SPEED SIGHT DISTANCE LIMIT RESTRICTION mph feet The second pass is made with the vehicles traveling at the same pre determined separation distance as the first run During this run the operator of the range tracking computer documents the beginning and end of each no
187. or data collection efforts to be made during the investigation The areas of concern can be grouped into three basic categories vehicle pedestrian and crashes and are addressed in this section Warrants for signal installation taken from the MUTCD will be correlated with the studies indicated This manual will be of assistance in conducting many of the studies indicated as we have noted the appropriate chapter or section VEHICLE A vehicle problem can normally be diagnosed during the field observation without great difficulty Some of these characteristics are excessive queue lengths slow queue dissipation rates and or large traffic volumes using the intersection etc Typically the data collected to determine the extent of a vehicle problem includes one or more of the following a Hourly approach volumes from the turning movement count Chapter 4 for the highest hours of an average day as required for MUTCD Warrants 1 5 and 7 9 MUTCD Sections 4C 02 4C 06 and 4C 08 4C 10 b Stop sign delay study Chapter 8 c Verification from the condition diagram Chapter 5 that the distance to the nearest signal in each direction 15 greater than 1000 feet as required for MUTCD Warrant 6 MUTCD Section 4C 07 and the location meets the recommended signal spacing in access policy see Chapter II of the WYDOT Access Manual d Determination from the condition diagram Chapter 5 of
188. or each direction of travel Testing should be conducted separately for each direction of travel On each test run the recorder must carefully observe the position of the ball throughout the length of the curve and record the deflection reading that occurs when the vehicle is as nearly as possible driving the exact radius of the curve TRAFFIC STUDIES MANUAL Page 73 March 9 2011 12 11 4 1 2 3 4 5 6 7 9 If the reading ball bank indicator for test run does exceed acceptable level as indicated by the recommended criteria in Table 11 1 then the speed of the vehicle 15 increased by 5 mph and the test is repeated The vehicle speed is repeatedly increased in 5 mph increments until the ball bank indicator reading exceeds an acceptable level The curve advisory speed 15 set at the nearest 5 mph incremental speed that is closest to where the ball bank indicator reading reaches the maximum acceptable level ESTABLISHING CURVE ADVISORY SPEEDS Using either of the two methods noted above design speed equation or ball bank indicator should result in the same advisory speed for a curve The advisory speed for the curve should be set at the 5 mph increment nearest to this maximum comfortable speed The advisory speed to be posted should not be arbitrarily reduced below the comfortable speed determined using these methods because an unrealistically low advisory speed will lose credibility amo
189. or more times since original construction As a result of resurfacing the superelevation of the curve may have changed and the original plans may no longer be representative of field conditions In other cases the original plans may no longer be available The WYDOT Highway Features File HFF contains horizontal alignment data as taken from as built plans for all State Highways in Wyoming The HFF data includes the reference marker of the middle of the curve the curve length and the change in direction or delta of the curve The radius of the curve can be calculated from the curve length and delta using the following equation TRAFFIC STUDIES MANUAL Page 70 March 9 2011 Equation 11 2 R 180 An Where R Curve radius feet L Curve length feet A Change in direction degrees TL Pi approximately 3 14 5 WYDOT s Pavement Management System PMS uses Pathways Services Inc and Pathview II software to gather and maintain state of the art pavement condition data and video images of the State Highway System The Pathview II data contains multiple sensor readings along the roadway including the cross slope of the roadway recorded in decimal degrees throughout the roadway system The superelevation on a given curve can be determined by Equation 11 3 Equation 11 3 e tan CS x 100 Where e Superelevation 90 CS Cross slope on subject curve from Pathview II 11 3 BALL BANK INDICATOR METHOD 1 The ball b
190. osition The net result 15 the indicator reading in degrees of deflection see Figure 11 3 Figure 11 3 Example Ball Bank Indicator Readings ZERO POSITION INDICATES 10 LEFT BANK Source FDOT Manual on Uniform Traffic Studies Testing should start well in advance of the curve being evaluated so the driver can reach the test speed at a distance of at least 1 4 mile in advance of the beginning of the curve The first trial run should be made at a speed multiple of 5 mph somewhat below the anticipated advisory speed The driver should enter the curve at the predetermined test speed and should try to maintain the assumed speed throughout the curve The path of the car should be maintained as nearly as possible in the center of the inner most lane the lane closest to the inside edge of the curve in the direction of travel If there 15 more than one lane the direction of travel and these lanes have differing superelevation rates drive in the lane with the lowest amount of superelevation Subsequent trial runs are conducted at 5 mph speed increments On each test run the driver should maintain the same speed throughout the length of the curve Because it 15 often difficult to drive the exact radius of the curve and keep the vehicle at a constant speed cruise control helps to maintain a constant speed the curve should be driven a number of times until at least two matching ball bank readings 1 e number of degrees are obtained f
191. other specified permitted errors Any exceptions to the previously noted standards should be approved by the State Traffic Engineer on a project by project basis Table 14 1 APPROXIMATE MINIMUM SAMPLE SIZE REQUIREMENTS FOR TRAVEL TIME AND DELAY STUDIES WITH 95 PERCENT CONFIDENCE LEVEL Average Range in Minimum Number of Runs Running Speed for Specified Permitted Error pur 3 0 4 0 5 0 2 5 5 0 10 0 15 0 20 0 Interpolation should be used when is other than the numbers shown in column 1 TRAFFIC STUDIES MANUAL Page 100 March 9 2011 144 COLLECTING THE DATA WYDOT uses PC Travel for Windows Travel Time and Delay Analysis Software to conduct travel time and delay studies This study method requires test vehicle with a transmission sensor installed TDC 8 traffic data collector New Link pushbutton switch connected to TDC 8 TDC 8 Sensor Interface Cable and PC Travel Field Worksheet see Figure 14 1 1 Define the starting point ending point and intermediate nodes Normally the starting ending and intermediate nodes are intersections but they can be other landmarks such as bridge abutments mile post markers or other fixed landmarks Pick points that can be easily identified now and when future after runs may be collected The drawing below shows a simplified diagram of a typical study route There is a starting node which could be an intersection four nodes which could be signalized in
192. our Mile Road LAO8A MP 13 11 MP 13 57 Results of Engineering and Traffic Investigation Method Use Visual inspection and engineering judgement Free flow spot speeds to determine 85 percentile speed and pace Summery of Results The existing speed limit is 40 mph The 85 percentile speeds are 51 mph eastbound and 52 mph westbound with a ten mile per hour pace of 39 mph to 48 mph in both directions Recommendations Post a 50 mph speed limit by replacing the existing 40 mph speed limit sign westbound at MP 15 11 with a 50 mph sign Replace the existing eastbound 40 mph sign at MP 13 43 with a 50 mph speed limit sign Approve Mas 1 13 3 lt ict Engineer ale State Traffic Engineer Date ORDER TO ESTABLISH RESTRICTED SPEED ZONE t is detezmined and declared that hfty 50 miles per hour is a sate and reasonable speed limit of the locatior designated and the District Engineer at said location is hereby directed to cause appropriate signs to be erected wit the concurrence of the State Traffic Engineer thereat giving notice of said speec limits 1 Dated this f 11 day of 2063 Director ERECTION OF SIGNS The erection of approp iate sigas in compliance with the d was completed LIES 2058 m TRAFFIC STUDIES MANUAL Page 95 March 9 2011 This page Intentionally left blank TRAFFIC STUDIES MANUAL Page 96 March 9 2011 14 1 1 2 3 4 C
193. passing zone on the computer as well as on the pavement by painting a mark on the highway with a short burst of paint from the paint canister s nozzle using the remote actuator The operator also keeps track of the DMI reading and marks the beginning of the short no passing zones prior to the actual point where the sight restriction begins The DMI reading 1s also monitored in the areas of closely spaced successive no passing zones so the operator does not mark the end of the first or the beginning of the second no passing zone The third and final pass repeats the same process as the second pass but in the opposite direction At the completion of the third pass the roadway is marked in each direction with a paint mark at the beginning and end of each no passing zone in each lane The District striping crew then follows up the range tracking crew by permanently marking the beginning and end of each no passing zone with delineator posts and the respective pavement markings are applied ONE VEHICLE METHOD This method should only be used as a last resort for emergency situations where some type of reasonable no passing zone markings must be established prior to the roadway being properly range tracked by the range tracking crew TRAFFIC STUDIES MANUAL Page 82 March 9 2011 2 3 4 5 This method only requires one employee in a vehicle equipped with DMI To mark curve or hill for passing sight distance the driver moves slo
194. perly display on the Display sheets This 40 mph range 15 sufficient for almost all free flow speed conditions In the rare case where speeds spanning more than 40 mph may be recorded the highest and lowest speeds can be disregarded without seriously affecting the speed study statistics If that doesn t reduce the speed range to 40 mph or less then the speed statistics for that case will have to be calculated manually SPEED STUDY DATA COLLECTION SHEET The Speed Study Data Collection Sheet Form TR 10 has been developed in conjunction with the Speed Study Worksheet Form TR 11 for the collection of speed data in the field An example of a blank collection sheet is shown in Figure 13 1 In order to limit the range of speeds to what 1s allowed by the worksheet the lowest anticipated free flow speed at the study location must be entered in the red box The remaining speed values are then automatically updated To help determine what value to enter the red box Table 13 1 provides some guidance on what lowest anticipated free flow speeds might apply based on the posted speed limit and whether the area of the study 1s in an urban area urban rural fringe or in a rural area Table 13 1 Lowest Anticipated Free flow Speeds Prior to heading to the field to collect spot speed study data 1t is recommended that several Speed Study Data Collection Sheets having varying lower limits be printed out for use by the data collection personnel When colle
195. point fall above curve on Figure 40 7 Where there is a divided street having a median of sufficient width for pedestrians to wat the requirement applies separately each direction of wehicular traffic MOTE This warrant sha not be applied at locations where the distance to nearest traffic control signa along the major street is fess than 300 fi unless the proposed traffic control signal wall nat restrict the progressive movement of traffic WARRANT 5 School Crossing Mot Applicable See School Crossing Warrant Sheet TRAFFIC STUDIES MANUAL Page 21 March 9 2011 Figure 3 2 Example Traffic Signal Warrants Worksheet Page 3 of 6 Form TR 01 Revised 917 10 Page 3 of B WYOMING DEPARTMENT OF TRANSPORTATION TRAFFIC SIGNAL WARRANTS WARRANT 6 Coordinated Signal System SATISFIED Es NO X MINIMUM REGUIREMENT ON ONE WAY STREET STREET THAT HAS TRAFFIC PREDOMINANTLY IN ONE DIRECTION THE ADJACENT TRAFFIC CONTROL SIGNALS ARE SO FAR APART THAT THEY DO NOT PROVIDE THE NECESSARY DEGREE OF VEHICULAR PLATOONMING ON A TWO WAY STREET ADJACENT TRAFFIC CONTROL SIGNALS DO NOT PROVIDE THE NECESSARY DEGREE OF VEHICULAR PLATOONING AND THE PROPOSED AND ADJACENT TRAFFIC CONTROL SIGNALS WILL COLLECTIVELY PROVIDE A PROGRESSIVE OPERATION WARRANT 7 Crash Experience SATISFIED YES ADEQUATE TRIAL OF ALTERNATIVES WITH SATISFACTORY OBSERVANCE AND ENFORCEMENT HAS FAILED TO REDUCE THE
196. r Motor Motor Motor Motor Motor Motor Motor Motor Motor Motor Motor Motor Motor Motor Motor Motor Motor Veh Veh Veh Veh Veh Veh Veh Veh Veh Veh Veh Veh Veh Veh Veh Veh Veh Veh Veh Pedestria Motor Motor Motor Motor Motor Motor Motor Motor Motor Motor Motor Motor Motor Motor Motor Motor Motor Motor Veh Veh Veh Veh Veh Veh Veh Veh Veh Veh Veh Veh Veh Veh Veh Veh Veh Veh COLL TYPE Sideswipe Angle Dir Rear End Other Other Other Other Other Rear End Other Other Sideswipe Rear End Rear End Angle Dir Rear End Other Rear End Rear End Unknown Angle Dir Head On Other Rear End Other Rear End Angle Rig Angle Fr Rear End Rear End Rear End Rear to F Angle Rig Sideswipe Angle Fr Rear End Angle Sam Angle Dir LIGHTING Daylight Daylight Daylight Daylight Daylight Daylight Daylight Daylight Daylight Daylight Daylight Darkness Darkness Daylight Darkness Daylight Daylight Daylight Daylight Darkness Daylight Daylight Daylight Dusk Daylight Dusk Darkness Daylight Daylight Daylight Daylight Daylight Daylight Daylight Daylight Daylight Daylight Daylight ROAD COND Dry Dry Dry Dry Dry Dry Dry Dry Dry Dry Wet Dry Ice Frost Dry Dry Dry Dry Dry Dry Dry Dry Dry Dry Snow Unknown Dry Snow Dry Dry Dry Dry Dry Dry Dry Dry Wet Snow Dry March 9 2011 DUI Nul Nul Nul Nul Nul Nul Nul Nul Nul N
197. rator of the range tracking computer observes that the lead vehicle s target disappears the beginning of a no passing zone is documented on the range tracking computer When the lead vehicle s target reappears the end of the no passing zone 15 documented on the range tracking computer The process of documenting the beginning and end of each no passing zone location on the range tracking computer is continued throughout the segment until the end the section of roadway being checked 15 reached No marks are placed on the highway during this run After the first run the operator of the range tracking computer uses the computer s printouts to check the beginning and ending of each no passing zone The distance between successive no passing zones is checked and any locations where successive no passing zones are separated by less than the minimum distance between no passing zones as shown in Table 12 2 are noted In those cases the theoretical end of the first and beginning of the second no passing zone will not be marked on the roadway so the entire section between the closely spaced no passing zones will be striped as a continuous no passing zone The operator of the range tracking computer also checks the length of each no passing zone documented in the first run using the computer s printouts The length of each no passing zone that is less than 500 feet long is checked against the maximum sight distance restriction to allow omission of no passing z
198. ria at certain rural and or higher speed locations The application of the 70 criteria 15 applicable for intersections that lie within the built up area of an 1solated community having a population of less than 10 000 or where the posted or statutory speed limit or the 85th percentile speed on the major street exceeds 40 mph The application of the 7096 criteria based on population only applies to communities in Wyoming that do not currently have a signalized intersection reduction based on speed may still apply It also does not apply to intersections lying outside the incorporated limits of a community but within the urban planning boundaries typically within 3 miles or otherwise as determined by the Planning Program The application of the reduced warrant criteria based on speeds will be based on the posted speed limit If the speed limit is posted less than 40 mph the reduced criteria do not apply based on speeds reduction based on population may still apply If the posted speed limit is 45 mph or greater the reduced criteria applies If the speed limit is posted at 40 mph a spot speed study see Chapter 13 should be conducted at the intersection to determine whether or not 85th percentile speed 15 greater than 40 mph APPROACH LANES Engineering judgment must be exercised in applying various traffic signal warrants to cases where approaches consist of one lane plus one right or one left turn lane The site specific traffic ch
199. right turn lanes to the right gives drivers on the minor approach at the stop bar an unobstructed view of oncoming through traffic in the near lanes which allows for more effective use of gaps Similarly vehicles in the opposing left turn lane can block the views of left turning vehicles from the opposite direction as shown in Figure 18 6 Offsetting left turn lanes to the left as far as practical improves the visibility of opposing traffic Examples of positively offset left turn lanes are shown in Figure 18 7 By improving the visibility of opposing traffic drivers can more effectively use available gaps Consideration should be given to offset right and left turn lanes lane in locations with higher mainline operating speeds large percentage of turning trucks unique sight distance issues or crash experience where investigation of crash diagrams indicates that a safety benefit may be obtained from an offset turn lane When implementing offset auxiliary turn lanes make sure the horizontal geometry of the roadway does not negate the line of sight improvement Figure 18 6 Example of Negative Offset Left Turn Lane Sight Obstruction Source Missouri DOT TRAFFIC STUDIES MANUAL Page 152 March 9 2011 Figure 18 7 Examples of Positively Offset Left Turn Lanes Parallel Offset Left Turn Lanes Tapered Offset Left Turn Lanes Source AASHTO 2004 18 5 AUXILIARY TRUCK CLIMBING LANES The need for auxiliary truck climbing lanes is typ
200. rovided decisions concerning the specific operation must follow These include deciding which approaches will have turn phases whether the phases will operate as protected only mode protected permissive mode or variable mode and whether the turn phases will be operated as leading or lagging The simplest traffic control signal phase operation is commonly called two phase operation In this operation traffic on one street 15 assigned the right of way during one of the phases and traffic on the other street 1s assigned the right of way during the second phase If pedestrian signal heads are provided at the intersection Walk and flashing Don t Walk indications for pedestrians crossing a street are simultaneously displayed with the adjacent vehicular indications Drivers making left turns may do so but must first wait for an adequate gap in oncoming traffic and also must yield to any pedestrians in the crosswalk which they will be turning across all left turns are made in the permissive only mode Two phase operation may be used where separate turn lanes exist or where turning and through movements are made from a share use lane Two phase operation functions most effectively when there are relatively few left turns where there are sufficient adequate gaps in oncoming traffic and adjacent pedestrian movements to accommodate the volume of left turns being made and where there are minimal conflicts between pedestrians and turning vehicles TRAFFIC ST
201. rsection Near a Grade Crossing One Approach Lane at the Track Crossing Major Street Minor Street J MINOR STREET CROSSING APPROACH EQUIVALENT VPH o Y 25 iti M 100 200 300 400 500 600 700 800 MAJOR STREET TOTAL OF BOTH APPROACHES VEHICLES PER HOUR 25 vph applies as the lower threshold volume after applying the adjustment factors In Tables 4C 2 4C 3 and or 4C 4 If appropriate TRAFFIC STUDIES MANUAL Page 27 March 9 2011 3 8 WARRANT 1 EIGHT HOUR VEHICULAR VOLUME The Eight Hour Vehicular Volume signal warrant is broken into three conditions that are detailed in Section 4C 02 of the MUTCD The Minimum Vehicular Volume Condition A is intended for application at locations where a large volume of intersecting traffic is the principal reason to consider installing a traffic control signal The Interruption of Continuous Traffic Condition B is intended for application at locations where Condition A is not satisfied and where the traffic volume on a major street is so heavy that traffic on a minor intersecting street suffers excessive delay or conflict in entering or crossing the major street The combination of Conditions A and is intended for application at locations where Condition A is not satisfied and Condition B is not satisfied and should be applied only after an adequate trial of other alternatives that could cause less
202. s 7 Figure 9 3gives an example of a gap study that was performed using the stop sign delay study procedure TRAFFIC STUDIES MANUAL Page 55 March 9 2011 Figure 9 3 Example of Gap Study Using Stop Sign Delay Procedure Intersection Main St amp D St Counted by JDT Wyoming Department of Transportation Traffic Program oafety amp Studies Section Cheyenne WY Weather Comments Gaps on Main St Q D St Page No 1 Beginning of Gap End of Gap Gap Size L N Joined Queue Released From Delay Queue 111 3 30 00 PM 3 30 12 PM 12 112 3 30 12 PM 3 30 17 PM 5 113 3 30 18 PM 3 30 22 PM 4 114 3 30 22 PM 3 30 34 PM 12 115 3 30 35 PM 3 30 43 PM 8 116 3 30 44 PM 3 30 52 PM 8 117 3 30 53 PM 3 31 05 PM 12 118 3 31 06 PM 3 31 11 PM 5 119 3 31 11 PM 3 31 16 PM 5 1 10 3 31 16 PM 3 31 21 PM 5 11 11 3 31 21 PM 3 31 22 PM 1 1 12 3 31 22 PM 3 31 24 PM 2 1 13 3 31 24 PM 3 31 26 PM 2 1 14 3 31 26 PM 3 31 37 PM 11 11 15 3 31 37 PM 3 31 49 PM 12 1 16 3 31 49 PM 3 31 51 PM 2 1 17 3 31 51 PM 3 31 53 PM 2 1 18 3 31 53 PM 3 32 01 PM 8 1 19 3 32 01 PM 3 32 06 PM 5 1 20 3 32 06 PM 3 32 26 PM 20 1 21 3 32 26 PM 3 32 36 PM 10 1122 3 32 40 PM 3 32 43 PM 3 1 23 3 32 44 PM 3 32 46 PM 2 1 24 3 32 47 PM 3 32 53 PM 6 1125 3 32 54 PM 3 32 55 PM 1 1 26 3 32 55 PM 3
203. s roads with fully controlled access no at grade intersections but does suggest some general criteria that may apply when considering the installation of lighting Lighting of rural at grade intersections is warranted if the geometric conditions mentioned in the AASHTO Guide exist or if the intersection scores a total of 50 or more points on the Intersection Lighting Criteria form see Figure 15 1 TRAFFIC STUDIES MANUAL Page 107 March 9 2011 Figure 15 1 Example Intersection Lighting Criteria WYOMING DEPARTMENT TRANSPORTATION DRUMS RURAL INTERSECTION LIGHTING CRITERIA Major Roadway US 30 Minor Roadway Whitney Rd CRITERIA 1 ROADWAY SYSTEM DESIGNATION POINTS Primary 10 points Secondary 5 points Major Primary 10 County 2 points Local or driveway points Minor County 2 CRITERIA 2 GEOMETRIC CONDITIONS Intersection Type Type Four leg B Four leg 5 points Three leg 2 points Roadside Development Quadrants Two or More 3 Two or more quadrants 5 points One quadrant 2 points No development 0 points Major Roadway Turn Lanes Turn Lanes Yes 0 5 points Yes 0 points Major Roadway Posted Speed Speed 55 5 Over 45 mph 5 points 45 mph or less 0 points Major Roadway Stopping Sight Distance Adequate Yes 0 Inadequate for operating speed 5 points Adequate for operating speed 0 points CRITERIA 3 TRAFFIC VOLUME Major Road Daily Volume Highest two way volume Major 8 080 10 5 000 vpd or more 10 p
204. s make sure the Print Data toggle on the Stop Sign Delay Print Setup screen is set to Print Data TRAFFIC STUDIES MANUAL Page 54 March 9 2011 Summary Information Final Summary Only 1 Minute 5 Minutes 15 Minutes 30 Minutes Minutes Grand T otal 2 Print Data Not Print Data Print Data From First nterval 3 30 00 Last Interval 5 30 00 Options Print Comments Intersection Drawing Intersection Photo Graph Totals Do Print Headings Hide Header Information Graph Color Preview Print Save Print Defaults Close Help Lane 1Ramshorn at D 6 SInce the software 15 set up to display Information concerning stop delays the output data from the stop sign delay study must be reinterpreted for use as a gap study as follows a b 4 f g Joined Queue 15 the time at the beginning of the measured Released from Queue 15 the time at the end of the measured Delay is the length of gap gap size in seconds Average Stopped Time 15 the average gap size Maximum Stopped Time is the maximum gap size measured Total Vehicle Count and Delayed Vehicle Count should match and is the total number of gaps measured Average Queue is a relative indicator of the amount of platooning the lower the value the more platooning individual gaps are not usually measured between successive vehicles in platoon
205. s chapter establishes WYDOT s warranting criteria for the construction of the various auxiliary lanes A section 15 also included in this chapter to assist with the review of Traffic Impact Studies submitted in accordance with the WYDOT Access Manual AUXILIARY LEFT TURN LANES Left turn lanes installed in the center of the roadway are intended to remove left turning vehicles from the through traffic flow This reduces the frequency of rear end collisions at locations where there is significant left turn ingress activity such as major driveways and public road intersections The use and design of auxiliary left turn lanes should be based on a traffic study In general auxiliary left turn lanes must be long enough to accommodate a safe deceleration distance and provide adequate storage for an expected peak hour turning traffic queue The following data are required to determine if an auxiliary left turn lane 15 warranted a Opposing Volume vph Vo The opposing volume includes only the right turn and through movements in the opposite direction of the left turning vehicle b Advancing Volume vph V4 The advancing volume includes the right turn left turn and through movements in the same direction as the left turning vehicle c Operating Speed mph The anticipated posted speed limit d Percentage of left turns in V 4 18 2 1 RURAL GUIDELINES 1 2 WYDOT uses 50 of AASHTO s advancing volume criteria for left turn
206. s notice from the public a civic organization business etc regarding their desire or need for a traffic signal to be installed or modified at a given site Often the traffic engineer or one of his her staff has observed the situation or another governmental agency has brought it to their attention 2 Regardless of the source the traffic engineer 15 obligated to respond However to respond in a professional manner requires some systematic investigation of the situation Before a full scale investigation 15 launched requiring a large amount of manpower and equipment the traffic engineer should conduct an observation of the site If a great deal of delay 15 encountered engineer should contact the reporting party about the action to be initiated 23 OBSERVATION OF CONCERN SYMPTOMS 1 During the initial observation or field investigation of the site a number of items should be noted The preparation of a condition diagram Chapter 5 should be made at this time if none exists for the site The condition diagram shows the location of traffic control devices intersection geometry and other physical features If the engineer has an existing condition diagram it should be updated if necessary Note that it is not necessary for this diagram to be drawn to scale 2 In addition to preparing a condition diagram the engineer should observe the operational characteristics of the location and note any unusual or significant circumstances Ide
207. s should be considered for all approaches to signalized intersections that have 10 or more left turns per hour 3 Left turn lanes should be considered on the minor leg approaches to signalized intersections in order to minimize delays to the higher volume major street traffic TRAFFIC STUDIES MANUAL Page 148 March 9 2011 Figure 18 2 Guide for Left Turn Lanes Two Lane Highways Speeds of 45 55 mph LEFT TURN WARRANTS 90 MPH 50 AASHTO CRITERIA EBEN 5 Left Turns E 1096 Left Turns 20 Left Turns 3090 Left Turns OPPOSING VOLUME Vo 200 400 600 ADVANCING VOLUME V VPH Figure 18 3 Guide for Left Turn Lanes on Two Lane Highways Speeds x 40 mph LEFT TURN WARRANTS 40 MPH 50 AASHTO CRITERIA VPH 5 Left Tums E 10 Left Turns 20 Turns 30 6 Left Turns 78 gt m gt u gn O o LL ADVANCING VOLUME V VPH TRAFFIC STUDIES MANUAL Page 149 March 9 2011 18 3 AUXILIARY RIGHT TURN LANES 1 The use of and design of dedicated right turn lanes should also be based on a traffic study In general dedicated right turn lanes should be provided in both rural and urban areas on two lane routes as shown in Figure 18 4 Figure 18 5 should be used to determine right turn lane warrants on four lane routes To use the figures peak hour traffic counts including directional splits will be required see Chapter 4 In addition
208. s used by WYDOT vehicle speeds should be measured using automated methods such as radar or laser speed detection The individual vehicle selection method 15 the preferred method of obtaining free flow speeds with sample sizes of at least 50 and preferably 100 vehicles per direction being considered representative samples The lower sample size can be used on lower volume 1 having two way traffic volumes of less than 1 000 vehicles per day roadways where the time to collect 100 samples per direction could be excessive An Excel spreadsheet has been developed to assist with the collection and analysis of spot speed study data The spreadsheet includes a Speed Study Data Collection Sheet Form TR 10 to be TRAFFIC STUDIES MANUAL Page 85 March 9 2011 3 13 3 1 2 3 4 5 printed out and used in the field for tabulating the speed samples by hand It also contains a data input sheet where the raw data from the data collection sheet can be input into the spreadsheet for detailed analysis Speed Study Worksheets Form TR 11 that provide detailed speed statistics for each direction and the combination of both directions as well as a clean computer printout of the data collection sheet are also included The worksheet was designed to where it can only process speed data having a maximum range of 40 mph between the highest recorded speed and the lowest recorded speed This limitation was required to allow the data to pro
209. seconds width Assuming 3 5 fi sec walking speed and 3 sex startup W3 5 3 Number of students crossing during highest crossing hour 36 From Pedestrian Gap Study Number of gaps exceeding 20 1 seconds 63 From Pedestrian Gap Study Number of gaps exceeding 40 3 1 2 G seconds From Pedestrian Gap Study Is there an existing traffic signal along the major street that is less than 300 feet away Ma Will a traffic signal at this location restrict the progressive movement of traffic Yes WARRANT School Crossing APPLICABLE YES No 1 SATISFIED NO There a minimum of 20 students crossing during the highest crossing hour Noj gt There are fewer adequate gaps in the major road traffic stream during the period when the children are using th crossing than the number af minutes in the same periad Effective total number of gaps available 63 Yes W The nearest traffic signal along the major road is located more than 300 feet away Or the nearest traffic signal within 300 feet but the proposed traffic signal will mot restrict progressive movement of traffic Dist to Nearest Signal Yes Nof NOTE Before a decision is made to install a traffic control signal on the basis of this warrant consideration shall first be given to the implementation of other remedial measures such as warning signs and flashers school speed zones school crossing guards
210. sonnel needed to perform a curve advisory speed study using the ball bank indicator method consists of a test vehicle intermediate size driver observer if necessary ball bank indicator Slope Meter safe curve indicator Distance Measuring Instrument DMI and the Curve Advisory Speed Study form Form TR 16 to input data Figure 11 2 is an example of how the test vehicle is equipped to perform a curve advisory speed study Figure 11 2 Example of Equipment Used for the Ball bank Indicator Method i W AE N Source Stephen Ford MCDOT To ensure proper results it is critical that the following steps be taken before starting test runs with the ball bank indicator a Inflate all tires to uniform pressure as recommended by the vehicle manufacturer b Calibrate the test vehicle s DMI c Zero the ball bank indicator The vehicle s DMI should be calibrated to the manufacture s recommendations to ensure accurate test results If the DMI used cannot display both speed and distance simultaneously once the DMI is properly calibrated the vehicle s speedometer should be correlated to DMI speed readings at each of the test speeds 1 every five mph increment over 20 mph If there are any discrepancies note the discrepancies so the driver can drive the vehicle at the correct speeds when doing the study e g if the speedometer reads 48 mph when the DMI reads 50 mph then drive the vehicle at 48 mph according to its speedom
211. street signal removal opponents will often argue that pedestrian safety 1s compromised with the removal of a signal However this belief has not been substantiated at previous signal removal locations Locations having relatively few typically 15 or less pedestrians crossing the major street during the peak hour have shown no increases in pedestrian crashes after signal removal While this information may be useful discussions with signal removal opponents on the subject of pedestrian safety will still require a very careful and tactful approach TRAFFIC STUDIES MANUAL Page 111 March 9 2011 16 2 3 WARRANTS 1 2 3 4 The MUTCD contains no specific warrants for the removal of traffic signals The primary indicator that a traffic signal may no longer be needed is the intersection s failure to satisfy any of the MUTCD signal installation warrants However it is possible that a signalized intersection that does not meet any of the warrants will meet at least one warrant after the signal is removed due to increases in crashes delay or traffic patterns Therefore the removal of a traffic signal requires additional engineering analysis If current or expected future traffic volumes meet any of the MUTCD warrants then signal removal should be deferred Sometimes traffic signals are installed at new intersections or at existing intersections based on projected volumes based on new development or construction in the area Unless
212. street unstopped movements at the expense of the minor street stopped movements When the major street traffic volumes are heavy there can be little or no opportunity for cross street access This places a definite limit on the application of TWSC Even when TWSC capacity 15 not exceeded there is often strong public pressure to keep the signals rather than convert to TWSC at the intersection Unless there 1s an interconnected street network that will allow traffic on the minor street reasonable access to another signalized access to the major street that public pressure can be almost impossible to overcome If the signal being removed 15 located between existing coordinated signals TWSC 15 the only acceptable form of alternative traffic control If the spacing to adjacent signalized intersections is favorable the time space and time flow diagrams associated with each of the time of day traffic signal coordination plans should be carefully analyzed to determine if the adjacent signals will provide sufficient gaps in major street traffic to permit minor street traffic to enter without unacceptable delays 16 4 2 ALL WAY STOP CONTROL AWSC 1 2 AWSC should only be considered if the intersection meets the minimum volume criteria associated with the multiway stop criteria contained in Section 2B 07 of the MUTCD AWSC treats the cross street movements more favorably without the wasted time associated with traffic signals However the rat
213. t project Identifies mitigation costs responsibilities and timeline Appendices include traffic data collected worksheets and methodologies TRAFFIC STUDIES MANUAL Page 155 Date COMMENTS March 9 2011 This page Intentionally left blank TRAFFIC STUDIES MANUAL Page 156 March 9 2011
214. tablished in accordance with that manual no passing zones governed by passing sight distance 1 e horizontal and vertical curves shall be established in accordance with the guidelines provided in this chapter The purpose of a no passing zone study 15 to establish locations where it is not safe to pass and to mark those locations with no passing zone markings Locations that are not striped with no passing zone markings are not necessarily locations where it 1s safe to pass but rather where motorists may lawfully pass only if they can do so safely NO PASSING ZONE CRITERIA The criteria for checking and establishing no passing zones in the State of Wyoming shall be the minimum passing sight distance see Table 12 1 Minimum passing sight distance represents the minimum sight distance necessary at the critical position passing and passed vehicle abreast to permit a passing driver to perceive an opposing vehicle at a distance sufficient to allow safe completion of a passing maneuver Table 12 1 Minimum Passing Sieht Distance POSTED SPEED MINIMUM PASSING LIMIT SIGHT DISTANCE mph feet Use for highways posted 65 mph TRAFFIC STUDIES MANUAL Page 79 March 9 2011 2 3 4 Passing sight distance a vertical curve is distance at which an object 3 5 feet above pavement surface can just be seen from a point 3 5 feet above the pavement Similarly passing sight distance on a horizontal curve is the distan
215. ted points If the School Crossing warrant applies complete the School Crossing Signal Warrant Sheet Form TR 01a under the Wrnt 5 tab This first requires the completion of a pedestrian gap study see Chapter 9 If the Intersection Near a Grade Crossing warrant applies complete the Intersection Near a Grade Crossing Warrant worksheet Form TR 01b Enter the pertinent information on Wrnt 9 Input sheet then plot the highest point on the applicable figure 1 Figure 4C 9 for a single lane over the crossing or Figure 4C 10 for multiple lanes over the crossing Figure 3 2 consisting of 6 pages gives an example of a completed traffic signal warrant analysis using the Traffic Signal Warrants worksheet Figure 3 3 gives an example of a completed School Crossing Signal Warrant Sheet Figure 3 4 gives an example of a completed Intersection near a Grade Crossing Warrant Sheet TRAFFIC STUDIES MANUAL Page 19 March 9 2011 Figure 3 2 Example Traffic Signal Warrants Worksheet Page 1 of 6 7112 Gf WYOMING DEPARTMENT OF TRANSPORTATION TRAFFIC SIGNAL WARRANTS Calc by JDT Calc Date 09 17 10 Jackson j Teton Chk by Count Date 6 31 10 CITY DIST CO Major Street Broadway Posted Approach Speed 35 mph Lanes 2 Minor Street Gill Street Posted Approach Speed 30 mph Lanes 1 speed major street traffic gt 40 mph
216. ter the location so that the curve study location is thoroughly identified The highway route number s and or name county and maintenance section number should be included Enter the posted speed limit pavement condition date of study vehicle make model and year and the people performing the study 1 e driver and recorder in the appropriate spaces Include any information that may need to be considered in addition to data being collected in the Remarks area Enter the travel direction of the study vehicle through the curve and the reference markers for the start and end of the curve Enter the run speeds in 5 mph increments The first run should be made at a speed that is slightly lower than the anticipated maximum comfortable speed For existing curves with posted advisory speeds a good rule of thumb is to make the first run at a speed of 5 mph below the existing advisory speed Enter the degree of deflection shown on the ball bank indicator as the vehicle passes through the curve at the initial run speed If the reading on the first run 15 significantly less that the respective threshold reading in Table 11 1 only one run is necessary at that run speed and you can make the next run at the next higher speed Once the readings are relatively close to the threshold values drive the curve at each run speed up to three times or until at least two matching ball bank readings are obtained for each direction of travel In the example in Fig
217. tersections and an ending node Make a rough sketch of the route clearly showing the starting and ending points and list the intermediate nodes you want to use see step 4 You don t have to make every intersection a node It is important to understand the type of information you want the data to give you before you define the route and nodes Don t use more nodes than you really need it just needlessly complicates the analysis amp _ Data Route Start Node 1 Node 2 Node 3 Node 4 End 2 You should always keep field notes when you do travel time studies The field notes help you keep track of the runs when you get back to the office The PC Travel Field Worksheet will help you store all of the information about the runs you make Figure 14 1 is an example of a worksheet that has been filled out to give you an idea of how the form is used Before you start the data collection fill in the general information about the session at the top of the sheet List the starting point ending point and any intermediate nodes 3 Connect the TDC to the vehicle s transmission sensor using the Sensor Interface Cable and Plug the pushbutton switch into the jack labeled Bank 1 on the side of the TDC 8 This 15 actually connected to the Bank 2 switch in the counter The labels for the two jacks are reversed on the side of the TDC 8 4 Calibrate the TDC 8 according to the procedure described in the PC Travel for Windows Reference Ma
218. the ITE Trip Generation Manual may be used as an estimate for peak hour traffic counts when new or modified development is involved The Planning Program can provide necessary growth rates for design year analyses 2 The following data are required to determine if an auxiliary right turn lane is warranted a Advancing Volume vph The advancing volume includes the right turn left turn and through movements in the same direction as the right turning vehicle b Right Turning Volume vph The right turning volume is the number of advancing vehicles turning right c Operating Speed mph The anticipated posted speed limit 3 If the combination of major road approach volume and right turn volume intersects above or to the right of the speed trend line corresponding to the major road operating speed then a right turn lane can be considered appropriate Figure 18 4 us Turn Lane Guidelines for Two Lane Highways Right T urn Volume Major Road Volume one direction TRAFFIC STUDIES MANUAL Page 150 March 9 2011 Figure 18 5 Right Turn Lane Guidelines for Four Lane Highways Fight T urn Volume Major Road Volume one direction Note A right turn lane is typically not warranted for right turn volumes of less than 10 vph However criteria other than volume such as crash experience may be used to justify a right turn lane 4 Dedicated right turn lanes should also be strongly consid
219. tion by indicating the approach direction of each approach 1 e Northbound Southbound Eastbound and Westbound 3 For turning movement counts that will be used for signal warrant analysis the approaches should be in order of Northbound Southbound Eastbound and Westbound from left to right 4 Briefly describe the Weather Conditions and include any Comments that may influence the results of the data being collected For example a stalled vehicle that may temporarily restrict a vehicle movement during a time period should be noted 5 Figure 4 1 gives an example of a turning movement count that was completed using a TDC 8 count board and processed through the PetraPro software 4 3 AUTOMATED TURNING MOVEMENT COUNT Automated turning movement counts are collected using Miovision Technologies Polemount Video Collection Units VCUs and the data 15 processed and retrieved on Miovision s Traffic Data Online TDO servers TRAFFIC STUDIES MANUAL Page 31 March 9 2011 Figure 4 1 Example Turning Movement Count Wyoming Department of Transportation Intersection Main amp 5th St Counted By AA Weather Rainy Traffic Program Safety amp Studies Section Cheyenne WY File Name N Main amp 5th St Site Code 00000005 Start Date 6 5 2008 TRAFFIC STUDIES MANUAL Page 32 March 9 2011 Comments Pag
220. to MUTCD Figure 4 1 to determine if this warrant is satisfer WARRANT 3 Peak Hour Condition A for the same 1 hour of an averge day SATISFIED YES HO x 1 The total STOPPED delay experienced on one minor street approach controlled by a STOP sign equals FULFILLED exceeds 4 vehihrs for a 1 lane approach or 5 veh hrs for a 2Jane approach vel 71 wx Ave 20 48 wiVeh 20 7 The volume on the same minor street approach equals or exceeds 100 vph for ane moving ane of traffic or 150 woh far two moving lanes Actual volume 185 Hour Beginning 5 Yes The total entering volume serviced curing te hour equals ar exceeds 550 woh for intersections with three approaches or 200 vph for intersections with four or more approaches Actual volume 1834 Yes No Condition B SATISFIED YES X NO AM 8 11 12 1PM 3PM 4PM 5 est Approach Minor Sreet Does platted point fall above curve an Figure 40 37 Refer to MUTCD Figure 40 3 determine if this warrant is satisfied WARRANT 4 Pedestrian Volume Posted speed of major street traffic gt 35 mph 4 HOUR WARRANT SATISFIED YES No x 1 HOUR WARRANT SATISFIED YES x NO 11 12 PM 1PM 3PM 4PM 5PM Vehicular Volume Major Street Total Both Approaches Total Pedestrians Crossing Major Stree Does platted point fall above curve F gure 4 5 Does plotted
221. ttom 2 foot portion represents the object height for measuring stopping sight distance this will be further explained later in Section 6 3 3 The sighting rod should be 3 5 feet tall to represent the driver s eye height The sighting rod can be constructed out of the same type of wood but should be painted flat black The sighting rod and target rod are used in measuring sight distance 3 The methods to measure and analyze the approach sight distance for uncontrolled intersection intersection sight distance for STOP controlled intersections and stopping sight distance are described below TRAFFIC STUDIES MANUAL Page 37 March 9 2011 Figure 6 5 Example Sighting Rod left and Target Rod right Source CTRE 6 3 1 UNCONTROLLED INTERSECTIONS 1 For uncontrolled intersections the drivers of both approaching vehicles should able to see conflicting vehicles in adequate time to stop or slow to avoid a crash The required sight distance for safe operation at an uncontrolled intersection is directly related to the vehicle speeds and the distances traveled during perception reaction and braking time Table 6 1 lists the minimum recommended sight distances for specific design speeds For example for a speed limit of 30 mph 140 feet is the minimum recommended sight distance along that approach leg Table 6 1 Length of Sight Triangle Leg No Traffic Control Posted Speed Length of Leg X or Y mph feet NIN O1 O
222. tudy is to review crash history associated with the study intersection The crash analysis should include the latest five years of available crash data This data 15 used to identify any crash patterns or trends that may be occurring at the intersection 2 WYDOT has several tools for the retrieval and analysis of crash data a Individual crash reports are contained on the ReportBeam website Users must obtain a username and password from the Highway Safety Program in order to access the online crash data b The Wyoming Electronic Crash Reporting System WECRS crash database can be queried using Crystal Reports to get a list of crashes at a specific intersection or along a specific corridor c The WECRS crash data 15 periodically typically quarterly processed through the Critical Analysis Reporting Environment CARE which can be used to locate and analyze crash data in a number of ways such as pin maps hotspot anaylsis etc 7 2 COLLISION DIAGRAM 1 The collision diagram is used to pictorially represent different types of crashes that have occurred at a particular intersection Figure 7 1 1s an example of a collision diagram Collision diagrams are typically generated by Intersection Magic for the referenced intersection 2 intersection related crashes should be shown on the diagram with their respective Crash ID numbers The primary graphic consideration is to properly show the direction of original travel coupled w
223. ture check YES and defer signal removal 4 Special justifications Note whether or not the signal was installed based on any special justifications that are still valid If the signal was installed based on special justification per Section 16 2 4 that 15 still valid note what the justification is in the comments field and check the YES box If the installation was based on a special justification that is no longer valid note what the justification was and briefly explain why it is no longer valid in the comments field then check the NO box If there was no special justification simply check the NO box 5 If you checked YES for any of the above criteria consider deferring the signal removal unless there 15 strong local support for the signal s removal Otherwise proceed with the detailed analysis An example of Signal Removal Analysis worksheet is shown in Figure 16 4 STAGE 3 DETAILED ANALYSIS TWO WAY STOP CONTROL This analysis 15 pursued only if the intersection survives the preliminary screening process It involves predicting the impacts from signal removal and installation of two way stop control STAGE 3 1 EXPECTED INFLUENCE ON CRASHES 1 From Table 16 1 list the minimum required volume for determining the Volume Magnitude The minimum required volume is dependent on the number of lanes per approach See Section 3 4 about how to determine the number of lanes to use when turn lanes are present 2 List the major street
224. ul Nul Nul Nul Nul Nul Nul Nul Nul Nul Nul Nul Nul Nul Nul Nul Nul Nul Nul Nul Nul Nul Nul Nul Nul Nul Nul Nul Nul Figure 7 3 Example Crystal Reports Crash List CRASH HISTORY FOR SHERIDAN AT THE INTERSECTION OF MAIN ST 8 5TH ST FOR THE PERIOD JAN 1 2009 THROUGH JAN 51 2011 TIME REPORT CRASH HUM NUM JUNCTION OF DIRECTION ACTIVITY FIRST HARMFUL LIGHT ROAD DRIVER HUMBER LOCATION KIL RELATION COLLISION PRIOR COND COND ACTION 2009 0062108 1835 2005039631 N MAIN Intersection Related Rear End Front to Rear Straight Ahead Motor Vehicle In Transport on Roadway Dry Following too Close STANY 3 36 Straight Ahead Motor Vehicle In Transport on Roadway No improper Driving 1012008 800 210512624 STANY 335 0 0 Intersection Rear Front to Rear East Straight Ahead Motor Vehicle In Transport Roadway Dry Following too Close MAIN East Siopped In Trame Motor In Transport an improper Driving 711942108 1535 200511777 STH STAVY 33D 1 Intersection Related Rear End Front to Rear East Straight Ahead Motor Vehicle In Transport on Roadway Dsayilighi Dry Following too Close ST East Stopped In Trafe Motor Vehicle In Transport an Roadway No improper Driving East Stopped Traffic Motor Vehicle In Transport on Roadway improper Driving 8 1442108 1108 200512355 STH STAY 33D
225. ull one hour blocks Also any count intervals that form incomplete hours must be deleted prior to changing the interval length i PetraPro File Edit View Insert Format Tools Window Help ord oc qm Merge Wizard Correction Factor Graphs Variable Width Graph Change Interval Length d 5 Minutes 15 Minutes Online Map k 30 Minutes maj 60 Minutes M Please Select an Option Go straight to the Intersection Design tool Delete an approach along with all the references to it Add a new approach and reference it from the currently existing approaches Change the direction of an approach Rotate the position of the count board Delete a set of columns Peds 4 Once all of the data is entered on the Input Sheet additional data for the Crash Experience warrant must be entered on Pg 3 of the worksheet a Under sub section A select X if adequate trial of alternatives to reduce crashes has failed to reduce the crash experience at the intersection TRAFFIC STUDIES MANUAL Page 17 March 9 2011 WARRANT 7 Crash Experience SATISFIED 5 NO X ENFORCEMENT HAS FAILED TO REDUCE THE CRASH FREQUENCY AND Yes NO Wi ONE WARRANT WARRANT 1A MINIMUM VEHICULAR VOLUME ves in crashes SATISFIED AT WARRANT 1B INTERRUPTION OF CONTINUOUS TRAFFIC Yes A NO X 80 WARRANT 4 PEDESTRIAN VOLUME Yel No
226. ulti legged intersections intersections with low but balanced traffic volumes and intersections in which drivers views of approaching traffic are limited 4 When a traffic control signal 15 operated in the flashing mode as part of the planned signal operation the crash patterns should be monitored Signal operation should be changed to stop and go operation if the crash pattern or severity increases The following criteria can justify eliminating the flashing operation a 3 or more right angle crashes in one year that occur during flashing operation b 5 or more right angle crashes in two years that occur during flashing operations 5 Fully actuated signals that have protected only left turn phasing should not be operated in time of day flash 10 11 OPERATIONAL REVIEWS Whenever a new traffic control signal is installed or an existing signal is significantly modified an operational review should be performed on the signal to verify that it is operating as intended The operational review should be conducted by the District Traffic Engineer or Safety and Studies Section personnel as soon after all work is completed as possible normally within 30 days 10 11 1 SIGNALIZED INTERSECTION CHECKLIST An operational review consists of verifying that the traffic signal controls traffic as intended that all of the signal equipment is functioning properly and that all associated signs and markings are installed properly An Operational R
227. ure 11 4 the first test run was made at 30 mph in the northbound direction with a ball bank indicator reading of 5 This is well below the suggested criteria of 10 for a speed of 30 mph Therefore on the return pass in the southbound direction the first run was made at 35 mph and resulted in a reading of 7 This is still well below the threshold reading of 10 for speeds greater than 25 mph Therefore the next run in the northbound direction was made at 40 mph and resulted in a reading of 9 which is close to the threshold value The return pass in the southbound direction was also made at 40 mph and gave a reading of 10 Test runs at 40 mph were repeated in each direction until there were two readings of 10 in each direction These are the highest readings attained without exceeding the suggested criteria of 10 for a speed greater than 25 mph as shown in Table 11 1 This study would result in an advisory speed of 40 mph for both directions of travel for this curve In the example since one run in each direction at 40 mph resulted in a reading of 9 an additional run in each direction was made at the next higher run speed of 45 mph to see what readings would be achieved if the advisory speed were 5 mph higher Those runs were purely optional TRAFFIC STUDIES MANUAL Page 75 March 9 2011 Figure 11 4 Example of Curve Advisory Speed Study Form CURVE ADVISORY SPEED STUDY ROUTE Wyo 132 COUNTY Fremont SECTION FR 07A POSTED SPEED
228. urn lanes are provided from the minor street onto the major street Acceleration lanes may also be appropriate where crash experience indicates a problem with right turning entering vehicles The right turn acceleration lane should be sufficiently long to allow safe and efficient merge maneuvers The design length tapers and other features of right turn acceleration lanes shall be determined by the Geometrics Engineer 18 8 REVIEW OF TRAFFIC IMPACT STUDY REPORTS The WYDOT Access Manual 2005 covers the rules and regulations and policy for accesses to Wyoming State highways Chapter V of that manual discusses the basic requirements of a Traffic Impact Study TIS and when WYDOT requires the completion of a TIS A Traffic Impact Study Review Checklist has been developed to assist with the review process Figure 18 8 gives an example of the review checklist TRAFFIC STUDIES MANUAL Page 154 March 9 2011 Figure 18 8 Example Traffic Impact Study Review Checklist Traffic Impact Study Review Checklist Town Reviewed By Proposed Developrrent Report Developed Report contains clear description of proposed project Identifies project sponsor and contact person Performed and stamped by WY registered P E site Plan clearly labeled showing site location and surrounding streets Shows all current and proposed streets and accesses Shows distance between stroots accossos Includes circulation network and any construction phasing Identifies
229. vehicles in the opposing left turn lanes or to locations where there has been a documented high crash rate associated with left turn crashes involving left turns being made during the permissive mode Protected only left turn phasing should not be used for approaches with a shared use left turn and through movement lane unless the left turn and through movement operate simultaneously Protected permissive left turn phasing Protected permissive left turn phasing is a left turn operation in which both a protected green arrow interval and a permissive circular green or flashing yellow arrow interval is provided This operation is the preferred mode of left turn phasing when left turn phasing is warranted LEFT TURN PHASING CRITERIA The following criteria should be followed when deciding where separate left turn phasing should be used 1 2 Volumes a The volumes considered include the number of vehicles per hour make the left turn movement and the number of opposing conflicting through and right turn movements during the same hour Left turn phasing may be warranted if b There are at least 100 left turns during the peak hour and c The number of left turns multiplied by the number of opposing through and right turns during the peak hour exceeds 100 000 on a 4 lane street or 50 000 on a 2 lane street and d There are more than two left turn vehicles per cycle per approach at the end of the through movement green durin
230. veraged for the two peak hours 15 then calculated automatically For a 4 way intersection the sum of the total main road volume entry 2a and 2 times the side road volume per approach 2 times entry 2b 15 entered For example Total main road volume per hour 700 vph 2 x Average side road volume per approach 2 x 52 vph Total 804 vph For a T intersection the total main road volume plus the only side road approach volume is used The form automatically adjusts the total intersection approach volume calculation for a T intersection if the T Intersection box 1s checked For the average of the 2 peak hours read from the nomographs the per hour estimates of the four impact variables idling delay total delay total stops and excess fuel consumption Figure 16 8 is a list of nomographs by intersection type to guide you in the selection of the correct nomographs a Estimate the four impact variables for signal control On each nomograph e Enter the side road volume per approach from Step 2b use 52 for the example on the bottom horizontal axis e Draw a vertical line and locate on it the point equal to the total main road volume from Step 2a use 700 for the example on the family of lines representing signal control the dashed lines You will need to interpolate between the lines in order to find the point TRAFFIC STUDIES MANUAL Page 123 March 9 2011 4 5 e From this point draw a horizontal line to left vertica
231. volume two way and higher side street volume one approach only for the eight peak hours The major street and side street volumes are listed for the same hour However during the eight hours the higher volume on the side street may be one approach during some hours and on the opposite approach during the other hours 3 If both the major street and minor street volumes exceed the minimum values put a check in the box to the right The number of boxes checked is the Volume Magnitude 4 The average annual crash frequency 15 calculated as follows Equation 16 2 N CF x 12 t Where CF average annual crash frequency t number of months in the period covered N numberof intersection crashes during the period 5 The predicted change in annual crash frequency 15 then calculated using Equation 16 1 on page 114 A positive number indicates an expected increase in crashes and a negative number indicates and expected reduction in crashes STAGE 3 2 EXPECTED TRAFFIC FLOW RELATED IMPACTS This step requires the completion of the Signal Removal Impacts worksheet Form TR 04 using the appropriate nomographs as described below The following instructions explain how to use the nomographs and worksheet for predicting the estimated daily impacts of signal removal and replacement by two way stop control The worksheet is a PDF form that automatically calculates many of the fields TRAFFIC STUDIES MANUAL Page 122 March 9 2011 once the volu
232. which either are no longer perceived as problems or can be shown to be invalid The review should determine if such a special justification was used and whether or not it 15 still valid If still valid signal removal will be very difficult unless the special interest group is included in the decision making process and they buy into the signal removal concept A review of the original reasons for installing the signal should be done If all of the original needs are no longer present then consideration may continue A review of the political implications should also be done to determine if the climate 1s favorable to proceed STAGE 2 DETAILED REMOVAL ANALYSIS This is a more time consuming analysis process which is pursued only if the candidate intersection survives the preliminary screening process At this time a preliminary decision should be made concerning the type of intersection control that will be installed after the signal is removed namely two way stop control all way stop control or a roundabout The possible intersection control alternatives are discussed later on in this chapter see Section 16 4 Figure 16 2 gives an example of the decision process for Stage 2 of the signal removal study procedure in flowchart form TRAFFIC STUDIES MANUAL Page 112 March 9 2011 4 Figure 16 2 Sienal Removal Decision Process Stage 2 Detailed Analysis Compute predicted changes in crash frecuency resulting from signal removal
233. wly through it When the driver reaches the point at which the vista opens up and the driver 15 sure there 15 a stretch of road ahead which 15 sufficient for safe passing he or she stops the vehicle and places a paint mark on the right side of the roadway Drivers usually sight down the ditch line as an aid to finding this point when measuring curves for sight distance This point 15 the end of the no passing zone in the direction of travel The point where the vista opens is usually much easier to locate accurately than the point where the sight distance decreases below the minimum while coming into a curve or hill The driver then resets the DMI to 0 00 travels the required passing sight distance and stops to place a paint mark on the left side of the roadway This marks the beginning of the no passing zone in the opposite direction A trip through the site the opposite direction following the same procedure completes the determination of the location of the no passing zones for that site in both directions This one vehicle method essentially assumes a zero height object as there 15 no practical way to adjust this object height The method 1s therefore more likely to be conservative especially on hills where 3 5 feet high objects could be seen some distance further than zero height objects This method can miss some short no passing zones and may require a second pass in each direction to close any passing opportunities that are less than t

WYDOT TRAFFIC STUDIES MANUAL March 2011

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