Validation of traffic signal rules

The most important quantity for traffic lights is the time headway between vehicles when the traffic light turns green. As a rough estimate, one can take the above-mentioned value of 2000 vehicles per hour and convert it into time headways, resulting in $3600/2000 = 1.8$ seconds per vehicle. More exact values need to be taken from local field data.

There is discussion if maximal flow on a freeway can be larger than the outflow from a queue, such as at a traffic light. For the STCA model that we are using so far, this issue is not critical; for other car following models it may play a role. More discussion of this is in Chap. 27.

Figure: Number of vehicles going through the intersection per green phase, re-scaled to hourly flow rates per lane.