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Traffic signals and driver reaction time

Traffic signals and driver reaction time

Traffic signals and driver reaction time

Hi all,

I'm trying to work out the average/85 percentile reaction time for drivers responding to a green light at a set of traffic signals.  

My hunch says about 0.7 seconds and google seems to verify that, but I can't find any 'accepted' time in traffic guides i.e Austroads/RTA/Roads ACT. Does anyone know of standard which gives justified reaction times for traffic signals?


RE: Traffic signals and driver reaction time

Depends whether the driver is a teenager or not.  

Then again, adults like Don "The Snake" Prudomme would skew the curve.

Mike McCann
MMC Engineering

RE: Traffic signals and driver reaction time

I seem to recall that there was a formula for determining the length of time required for an amber light...


RE: Traffic signals and driver reaction time

Hi dik,

Yep yep, definately a formula for amber lights.  The reaction times given in those guidelines are in the order of 1.5 - 2.5 seconds.  I assume that these have safety factors built into them and allows for people of all ages...like 'The Snake':P

I'm more interested in driver reaction to green lights, I assume it's a lot faster (people such as myself can pre-empt the green light) especially at busier intersection.


RE: Traffic signals and driver reaction time

Hi Paul,

There was a paper written by Akçelik and Biggs (from 1987), which referenced a great deal of information on studies to do with the acceleration of vehicles at intersections. Unfortunately I cannot remember what it was titled., but I'm sure Google will find it for you.

I hope that helps.

Tim Absalom
Altus Traffic

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