Traffic signals provide direction and safety to road users by allocating and reallocating right of way. It is important to remember that traffic signals are community devices that provide a service to all types of road users.
Road users include motorists, cyclists and pedestrians.
The Perth metropolitan area now has over 850 sets of traffic signals under the central control of SCATS (Sydney Co-ordinated Adaptive Traffic System).
The goal of the SCATS system is to provide traffic signal coordination where possible, to improve traffic flow through adjacent intersections.
SCATS will typically co-ordinate traffic signals in the direction of the major traffic flow. Coordination is dependent on a number of factors including distance between intersections, traffic speed and the number of movements.
SCATS works by measuring congestion at strategically located collection points. With this information SCATS can ADJUST signal times in peak traffic.
The SCATS system can also be altered in real time to manage unexpected conditions and minimise delays caused by events or incidents.
Each intersection is individually assessed prior to the installation of traffic signals.
Advance warning lights, installed at the approaches to some traffic signals provide early warning that the traffic signals are about to change.
Advance warning flashing lights start to flash when the traffic signal lights are about to turn yellow and continue to flash while the traffic signals are red.
Turning vehicles giving way to pedestrians is an enforceable element of the road traffic code. Inappropriate driver behaviour should be reported to the police.
All movements at an intersection have a guaranteed minimum green time which will allow a vehicle to safely start up and enter an intersection. This time is calculated to be sufficient to cater for the width of the intersection.
The most likely cause is that the traffic signals have been set to coordinate with adjacent signalised intersections. In this case the SCATS computer is controlling the introduction of traffic movements in an effort to remain in sync with the other intersections.
Another possible cause is when the vehicle detection systems at an intersection have been damaged due to road works or normal wear in the road surface. When this occurs, cycling of the intersection does not operate normally.
On occasion the detection systems may need adjusting to register light vehicles like mopeds and bicycles.
The public can help by reporting traffic signal faults, including detection faults via our online report a fault form.
The inclusion of green arrow and red arrow displays usually increases complexity and reduces the capacity of an intersection.
This is typically the reason why all traffic signals don’t automatically have green arrow movements for all directions.
Traffic Engineers make an assessment in regards to whole of community benefit when considering requests for the addition of arrow controlled movements.
Requests in regards to displayed green time should take into consideration the capacity of an intersection. Capacity is affected by the number of lanes and the complexity at the intersection.
Increasing the green time for a leg of an intersection will either require taking green time away from other users or increasing other road users red (waiting time).
In most cases increasing green time for all directions will subsequently require increasing red time for all directions. Therefore, after the capacity of an intersection is reached, little is achieved by increasing green time.
There are some intersections in Perth that experience increased congestion at certain times of the day due to heavy right-turn movements.
To improve traffic flows and road safety, illuminated No Right Turn signals have been installed to prohibit these heavy right-turn movements.
Listed below are the NRT signalised intersections in Perth. All NRT signals operate at the following locations and times on weekdays excluding Public Holidays.
Albany Highway - Kelvin/Olga Road
(Also operates Saturdays 8am to 1.30 pm)
11am - 1pm
3pm to 6pm