Traffic signals control the flow of cars and people to improve safety on roads.
Council-controlled traffic signals
Council controls more than 3,300km of roads, with over 25,000 intersections. Traffic signals are needed at intersections that carry large numbers of cars and people. They make it safer for road users such as cyclists and pedestrians. They cost less than roundabouts and do not take up as much space. Council installs new traffic signals each year that cost from $500,000 to over $5,000,000.
Council controls more than 100 sets of traffic signals on the Sunshine Coast. The Department of Main Roads controls traffic signals on some major Coast roads such as Nicklin Way, Caloundra Road and Maroochydore Road.
How traffic signals work
Traffic signals are controlled by a local computer at each intersection from which, information can be retrieved remotely. The Main Roads Transport Management Centre at Maroochydore can also access them.
Road sensors detect vehicles as they pass and either change signals to green or extend the green light time. At busy times, the green light period may extend to a set limit and the signals will follow a set sequence. Some signals respond to traffic arriving at the intersection.
Traffic signal coordination
Traffic signals on some major roads need to:
- manage peak flows
- reduce delays
- allow vehicles in side streets to enter or cross over intersections.
Traffic signal displays
The length of time for a green traffic signal depends on traffic conditions and should always appear for a minimum of six seconds. On most major roads with a speed limit up to 60 km/h the yellow or amber light is displayed for four seconds. For higher speed roads, more time is provided for the yellow or amber traffic light.
An ‘all red’ light then applies on all roads following the yellow signal. This allows vehicles to move through the intersection before more traffic movements begin. This ‘all red’ time depends on the size of the intersection as larger intersections require longer clearance time.
Vehicle and bicycle detection
Detectors buried in the road sense when a car passes over them.
Bicycles can be detected at newer traffic signals, but it relies on iron-based metal to trigger the signals. If your bicycle is made of carbon-fibre, fibreglass, plastic or aluminium it may not be detected.
Pedestrian walk/don't walk symbols
The green person/red person symbols are used to signal walk/don't walk.
Please note, you do not need to get all the way across the road while the walk signal is on. The walk signal is used to inform people when they can start to cross but the flashing don't walk signals allow enough time to cross the road safely.
The most common traffic signal fault reported to council is faulty lights/lamps. The computer at each set of traffic signals sends fault messages to repair electricians to attend to the fault as soon as practically possible.
An important safety feature of traffic signals is that anyone approaching an intersection will see a minimum of three sets of traffic lights. If one or two traffic lights are out, the driver is still able to see a working set of traffic lights. The likelihood of all three traffic signals failing at once is very low. If one or two traffic signals are not working, there is no need to report this to council as the default has been detected by the computer and the repair electricians will already be planning to replace the bulb as part of their regular maintenance schedule.
If you think your car is not triggering the signals to change, there may be a fault with the detector. When this happens the signal automatically switches from detection mode to timed mode. Timed mode may not be the best way to deal with a range of traffic volumes, but it does allow safe signal operation until the fault can be repaired. These faults are automatically detected.
All other faults or problems with traffic signals should be reported to the Department of Transport and Main Roads Traffic Management Centre at any time day or night with a free call to 1800 678 501 or a local call to 13 19 40. This service is available 24 hours a day, 7 days a week.
Download the printable Traffic signals fact sheet (PDF, 294KB).