why do stop lights make you press the walk sign button?


This isn’t all stop lights. At many lights the button doesn’t do anything. But at some of them you do have to press the button. What is the purpose of making you press the button?

In: Engineering

The only stop lights I’ve seen with that button, are stop lights in places like highways or with high speed traffic that don’t need a stop light due to a low amount of people needing to cross.

Think of it like the turn arrow. If there’s no car in the turn lane the sensor will never be tripped and the arrow will never turn green. The button is the simplest way to let the system know someone wants to cross so the walk sign turns on rather than the don’t walk staying illuminated.

If no-one needs to cross the road, it would be pointless to stop the traffic. By requiring pedestrians to press the button you can keep the traffic interruptions to a minimum and only when there is actually someone who needs to cross.

For crossing a wide road, the normal green light may not be long enough for a pedestrian to safely cross, so the pedestrian indicator doesn’t go to walk on a normal cycle. Pushing that button makes the parallel green last longer, and activates the pedestrian indicator.

Normal lights will only activate the pedestrian crossing if a pedestrian presses the button – this saves motorists waiting when there is nobody needing to cross.

In really busy locations, some crossings will include the pedestrian crossing by default without a button – in some busy locations where there are virtually always pedestrians crossing. There will still be a button installed (even if it does nothing) so that all crossings are the same and people don’t get confused if some have buttons, and some don’t.

There are also some modern crossings that change how they function depending on the time of day – at busy periods they will follow one set of timings between cycles, or work automatically, at others the timings may change or the cycle will be based on sensors detecting vehicles and pedestrians pressing the button rather than a strictly timed sequence.