Section 11 Flashing arrow signs
Contents
1. Definitions These definitions are specific to this section see also Section 2 3 Definitions Aiming distance the distance between the flashing arrow sign and the eye of an approaching driver Cycle length the time interval between the start of the lamps being switched on and off and then on again to give a complete sequence of displays Flashing arrow signs flashing electronic traffic control signs and associated equipment used at work sites and operated in one of the following modes Arrow right mode AR the lamps are energised to display an arrow which directs traffic to move or merge to the right Arrow left mode AL the lamps are energised to display an arrow which directs traffic to move or merge to the left June 2010 Issue RTA Traffic Control at Work Sites GJ 11 4 June 2010 Issue Double headed arrow mode DA the lamps are energised to display an arrow which directs traffic to move or merge both to the left and to the right It is usually used where the centre lane of a three lane carriageway is closed to traffic and generally in an emergency situation Warning mode W a pair of opposite diagonal lamps flash to give a strong warning or caution to approaching traffic Lamp matrix an arrangement of lamps that display a message or symbol when a set or pattern of lamps is turned on or flashed Monitoring lamps a set of two lamps at the rear of the sign which2. and other consumable components e keeping the equipment clean and tidy These requirements are detailed in the manufacturer s instructions 11 7 2 Major repairs If care is taken with the field service the equipment should remain in good working condition between major service inspections and overhauls If major faults develop the sign should be taken out of service and alternative June 2010 11 9 Issue Z Traffic Control at Work Sites traffic control arrangements made The sign should not be returned to service until the faults have been rectified 11 7 3 Administration procedures Refer to local office procedures in respect of administration costing and maintenance of flashing arrow signs as an item of small plant 11 10 June 2010 Issue
3. and 50 to 40 percent off time For diagonal flashing displays VV the on time and off time is the same The repetition rate for all modes is between 35 and 40 cycles per minute Two monitoring lamps are provided at the rear of the Type C sign to allow workers to monitor the mode of operation These lamps flash as shown in Table I 1 1 11 5 2 Sign boards Generally the flashing arrow sign unit should be positioned so as to be as near as possible in the driver s line of sight It is important to always locate signs to give the driver maximum visibility and hence time to understand June 2010 11 5 Issue Traffic Control at Work Sites and react to the sign message The visibility distance of the sign ie the distance at which the motorist can first become aware of the flashing arrow varies as shown in Table 1 2 The minimum sight distance that should be provided to the flashing arrow sign depends both on the vehicle type and vehicle speed in the approach to the work area Table 1 2 provides a guide to the sight distances appropriate for the three types of sign On high speed roads every effort should be made to position the sign to achieve the desirable minimum sight distance Sight distance Visibility Desirable Absolute distance m minimum minimum 5 50 Increase the sight distance by 2 for each 1 of downgrade Decrease the sight distance by 2 for each 1 of upgrade Table 11 2 Typical sight distances f
4. dirty or obstructed the lamps will not be as bright as they should be 11 8 June 2010 Issue RTA Traffic Control at Work Sites GJ 11 6 4 Setting up The equipment should be set up to the Manufacturer s Instructions with particular care to the siting and aiming of the signs to suit the layout arrangement being used and the geometry of the road approach to the sign 11 6 5 Trouble shooting The monitoring lamps should be regularly observed to confirm that the sign is operating in the appropriate mode for the work site It is also necessary to regularly inspect the front panel of the sign to ensure that all lamps are clean and alive If one lamp is not operating then check it and if it is blown replace with a new lamp If all lamps are out or all lamps are too dim for the conditions then check the battery or generator for charge If the charge is satisfactory but the lamps are still too dim for the conditions then check that the photocell is not being blocked from reading the true ambient light level 11 7 Maintenance 11 7 1 Field service Operators should familiarise themselves with the manufacturer s instructions A high level of field service is essential to maintain the sign in good condition to provide an effective warning to motorists at all times Field service usually covers e simple fault diagnosis and associated replacement of the faulty modules e routine maintenance and servicing including replacement of lamps
5. sign is not in use 11 3 RTA GJ Traffic Control at Work Sites All signs can operate in one of four modes as detailed in Table 11 1 Rear monitoring Flashing lamps for Type C Arrow Shaft and the right side arrow head right AR Arrow Shaft and the left side arrow head left AL Double Shaft and both the left and the right arrow side arrow heads DA Warning Pairs of diagonally opposite lamps W alternating flash Gives a general message of caution or draws attention to an important traffic control sign Note Lamp off E Lamp on Table II I Modes of operation 11 4 2 Wehicle mounted signs Type A signs are suitable for attachment to light vehicles such as cars panel vans or utilities or small plant items Type B signs are suitable for attachment to heavy vehicles such as trucks and large plant items They are generally used on mobile works such as longitudinal linemarking mobile survey vehicles patrol vehicles and on shadow trucks protecting groups of workers 11 4 3 Trailer mounted signs Type C signs are self contained trailer mounted units particularly designed for use on high speed roads such as rural divided roads where driver expectations are high They are generally used at short term or long term lane closures for work requiring one or more lanes to be closed for one or more shifts Where 11 4 June 2010 Issue RTA Traffic Control at Work Sites GJ the flashing arrow signs are to oper
6. Section Illuminated flashing arrow signs II I Introduction AS 3 12 2 This section provides the basic information to effectively use illuminated flashing arrow signs These signs comprise a matrix of lamps or LED aspects in the form of an arrow that is flashed in a cyclic manner to either the left or right indicating the direction in which approaching vehicles are to pass The equipment is to be operated in accordance with this section and with the manufacturer s instructions As part of the daily routine tasks and record keeping a log must be kept of the location and the period of display of the signs This documentation may be required in Court in case of an accident or other incident such as a traffic infringement Other bodies working on public roads are encouraged to follow these practices where they are applicable Refer to Section 6 Record keeping and reporting for more information Flashing arrow signs are intended to be applied primarily where a lane is closed or a diversion of traffic is required typically on a multilane carriageway They may also be adapted for mobile plant operation where only part of the road is blocked by the road plant but a clear direction to traffic is required as to which side of the plant traffic should pass through the mobile work site An example of this is longitudinal linemarking Note that this section does not replace the field service manual and operating instructions for each set of equipme
7. ate overnight or over weekends the associated signs and devices need to be either reflectorised or lit 11 4 4 Associated signposting and traffic arrangements Any additional or associated signposting or traffic arrangements that may be required to be used with flashing arrow signs is to conform to the requirements of this manual Using flashing arrow signs tends to downgrade the effectiveness of other devices at the work site so it is essential that the associated signs and devices be in very good condition and special care be taken in their erection The visibility distance for Type A B and C flashing arrow signs is 500 1000 and 1500 metres respectively Associated signs should be located in clear view of approaching drivers generally on the left side of the road However on winding alignment it may also be necessary to erect a sign or signs on the right hand side for clear viewing Duplicate signs on the right hand side of the road may be considered when a driver s view may be obscured by alignment buildings or heavy traffic The use of larger signs may be considered for high approach speeds 11 5 Equipment installation 11 5 1 Lamps The brightness of the lamps is adjusted by an automatic dimming control which dims the light output for night conditions A photocell detects the ambient light conditions that triggers the dimming facilities The flash rate for flashing arrow displays AL AR DA can vary from 50 to 60 percent on time
8. displays the mode of operation to the workers Monitoring lamps are only provided on the Type C sign Off time the period of cycle time all the lamps are off This is usually 50 to 40 percent of the cycle time On time the period of cycle time specific lamps are on This is usually 50 to 60 percent of the cycle time Visibility distance the maximum unobstructed distance the flashing displays are clearly seen under bright daylight conditions with the specified lamps fully energised Visors cylindrical matt black sleeves that are fitted around each lamp to shield them from incident light and reduce sun phantom effects General description of system 11 4 1 Illuminated flashing arrow sign equipment The following three size designations are used Type A and Type B signs are suitable for mounting permanently on the rear of a road construction vehicle fixed sign arrangement or on the cab of a truck or utility vehicle adjustable sign arrangement Cab mounted signs can be rotated to face either the front or the rear of the vehicle The sign can also be rotated and locked in the face down position for transport when the sign is not in use They may be powered from the vehicle s electrical system or from a separate power source Type C signs are trailer mounted with integral generator back up battery supply and control equipment Provision is made for the sign to be lowered rotated and locked for transport or when the
9. nd C signs are two and three times those for the Type A sign to take advantage of their greater size and visibility Type C signs not usually used on low speed roads Table 1 3 Aiming distances for various approach speeds Figure 1 1 M ustration of aiming and sight distance shows the relationship between these two distances used when setting up flashing arrow signs 11 5 3 Controls The controls available are e Power On Off e Mode selection e Mode monitoring Type C signs only June 2010 11 7 Issue Traffic Control at Work Sites AIMING DISTANCE gt SIGHT DISTANCE Figure 11 1 Illustration of aiming and sight distance 11 6 Operation 11 6 1 Control modes Although the layout and switch configuration may differ all controls have basically the same functions namely e Arrow Right AR e Arrow Left AL e Double Arrow DA e Warning WV 11 6 2 Flash rate The flash rate is fixed to the levels given in the Specifications and cannot be varied It is important to check that all lamps are functioning to give the correct display selected by the controls 11 6 3 Dimming The dimming facilities are automatic but care should be taken that any incident light from street lighting and or vehicle headlights falling on the photocell does not adversely interfere with the operation of the dimming feature The photocell should be occasionally cleaned since if it is
10. nt It is important that operators make themselves fully acquainted with the manufacturer s instructions and recommendations before attempting to operate the equipment 11 2 Approvals and specifications Illuminated flashing arrow signs shall comply with the relevant Australian Standards where they exist and RTA specifications FAS 5 or FAS 4 Part A The relevant Australian Standards are listed in FAS 5 and FAS 4 General operating instructions are given in this section In addition to the above only equipment that has been type approved by the RTA is to be used Testing of equipment is to be undertaken by the June 2010 11 1 Issue lt 1 3 Traffic Control at Work Sites RTA s Manager Traffic Equipment and Standards After type approval has been issued the Manufacturer or Selling Agent shall affix to the equipment a durable marking plate in the following format This equipment conforms to RTA NSW TYPE APPROVAL Noas The number shown on the marking plate shall be that shown on the Type Approval Certificate issued by the RTA Manager Traffic Equipment and Standards Requests for copies of Specification No FAS 5 FAS 4 Part A or a list of type approved equipment and arrangements for type approval of equipment should be directed to Manager Traffic Equipment and Standards Roads and Traffic Authority NSW Level 5 Pod D 99 Phillip Street PARRAMATTA NSW 2150 Telephone 02 8837 0116 Facsimile 02 8837 0025
11. or placement of flashing arrow signs The signs must be securely erected and anchored to prevent wind movement or interference by vandals This is especially true for Type C signs as these are intended to be operated unattended The signs must also be aimed carefully to direct their display to the approaching vehicles It is important that the sign be aimed to vehicles within the critical zone which covers the distances where drivers have time to react to the message and change lanes or stop if necessary This is particularly important if the approach alignment of the road is not straight Sighting is usually done by means of a sighting device which facilitates aiming of the sign display Such an aiming device must be substantially free of parallax error and must make allowance for the inherent downcast in the sealed beam lamps In the absence of a sighting device fitted to the sign aiming needs to be undertaken by trial and error Table 1 3 lists the recommended aiming distances from the sign near the start of the taper defining the lane closure June 2010 Issue Traffic Control at Work Sites GJ The aiming distance should not exceed the sight distance The recommended aiming distances for the Type A sign is based on the stopping distance PLUS the reaction distance for 2 5 seconds of travel PLUS an allowance of 30 metres for siting the sign past the start of the taper The aiming distances for Type B a
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