There are plenty of intersections where a walk signal comes on automatically, why do some intersections require a button push to initiate the walk signal when it doesn’t seem to make a difference in light timing or duration?
In: Engineering
In some cases, the traffic control cycle is suitable for pedestrian crossing. This works well at intersections where the cycle is timer based. The light just changes in a rotation. But there are other cases where this doesn’t work so well.
For example, some signal lights will only cycle when a vehicle is detected at the intersection. In this case, a pedestrian would have to wait for a car to arrive, which isn’t desirable.
Another cases is where the standard cycle isn’t safe for pedestrians. Fore example large intersections with dedicated left/right turn lanes and various dedicated signals are especially dangerous for pedestrians. The issue is that vehicles do not have adequate line of sight to clear the destination lane of pedestrians prior to entering the intersection. If a vehicle starts to go, only to see a pedestrian in the way, they would be forced to stop in a place that would be dangerous for everyone. Or they may panic and drive around the pedestrians in a way that is unsafe.
In these circumstances, the traffic control cycle will be altered to improve safety for pedestrian crossing. This can be implemented as a red signal in all directions, a delayed green for particular lanes of travel, or even a skip cycle where certain lanes of travel don’t get a green at all for that cycle.
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