Does pressing the button on pedestrian crossings actually make the lights change faster? © Getty Images

Does pressing the button on pedestrian crossings actually make the lights change faster?

Next time you try to cross the road, spare a thought for the complex computers controlling the green traffic light man.

Asked by: Manisha Desai, Bristol

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Yes, although the systems that control traffic signals vary in complexity. The simplest pedestrian crossings are just a single set of traffic lights that halt the traffic a couple of seconds after you press the waiting button.

At the top end are complex road junctions in city centres with multiple sets of traffic lights, remotely controlled by a central computer. Often these are interlinked and managed by elaborate software designed to optimise traffic flow across entire regions of the road network. They are programmed to take into account factors like the time of day, the volume of traffic and accidents or road works. Here, pedestrian crossings at individual junctions allow those on foot to cross while the traffic-light sequence is allowing drivers from other directions to proceed.

Though the green pedestrian light illuminates periodically as part of the usual sequence at such junctions, the traffic signals are programmed so that people on foot can interrupt the order by pressing the button.


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