Traffic lightInevitably during any talk of traffic conditions the topic of vehicles running red lights is brought up, especially by heavy vehicles. A search around the internet and news pages will show many an article about vehicles involved in accidents as a result. The consequences of this varying from a mere Red Light Infringement to the death of one of more people.

There will always be those that are selfish and just blow through red lights because they think they are the White Rabbit from Lewis Carroll’s Alice in Wonderland. But that situation is for another day.

In today’s blog I look at the timing of amber traffic lights, the issues with breaking in time for heavy vehicles and suggesting a way forward that should improve on the current system.

In all Australian states and territories traffic is not permitted to cross the stop line when the red traffic signal is displayed and is required to stop on display of the amber light if safe to do so.

In NSW the typical time setting for the display of an amber light ¹ is:

  • 4.0 seconds for up to and including 60 Kmh.
  • 4.5 seconds for 61 kmh to and including 70 kmh.
  • 5.0 seconds for 71 kmh to and including 80 kmh.
  • 5.5 seconds for 81 kmh to and including 90 kmh.
  • 6.4 seconds is the maximum time alloted

According to the report “Acceleration and deceleration testing of combination vehicles” to Main Roads Western Australia ² the following Schedule of stopping distances apply.

GCM Stopping distance (metres)
(Tonnes) 60 – 0 km/h 80 – 0 km/h 100 – 0 km/h
40 Dry 78 122.6 176.7
40 Wet * 91.86 146.84 237.3
50 Dry 79.3 124.6 179.6
50 Wet * 93.56 149.46 241.65
60 Dry 80.6 126.7 182.6
60 Wet * 95.26 152.21 246.15
* Includes Wet Correction Factor
  x 1.12 x 1.31 x 1.5
All distances include a reaction time component of
  + 33.3m + 44.4m + 55.5m

Delays in reaction time by the driver seriously impact on these distances and substantially eat into the time period of the amber light often leading to a red light before the vehicle has cleared the intersection. Variances in speed and/or road conditions, especially wet roads, also have an impact. So with all this in mind it is no wonder there are heavy vehicles that just do not or cannot stop in time.

So what can be done; more red light cameras, better driver training, more police?

How about this; for the last ten seconds of the green light phase the green light flashes steadily and then changes into the standard amber phase. This would allow drivers of heavy vehicles more time to prepare to stop. I am pretty sure this would be just a matter of a small code change in the traffic light control system and could lead to a substantial decrease in the number of red light incidents or accidents and a possible reduction in the road death toll.



  1. Cob Andco said:
    21 February 9:08 am

    Good luck getting someone in the RMS’s ivory tower to listen to you. When it comes to saving lives, the majestic hierarchy in that castle don’t even listen to their own staff and employees, or even the Highway Patrol Command for that matter, the kings of that castle need to see bodies in bags first. So sorry, but you don’t have much of a chance I’m afraid. But have a go anyways, cause it’s a good theory.