NPR recently did a story on whether those “close door >< ” elevator buttons actually work*. The reporter closed the story with “they are just like pedestrian push buttons…”
Well, we thought we’d clarify how those pedestrian push buttons work. Most buttons are tied into the signal cycle for the lights. Although pushing the button many times may make you feel better, pressing the push button once is all that is needed to activate the walk-signal request. The signal will serve the pedestrian at the next available opportunity.
This crossing opportunity, though, has its own “window of opportunity”. The walking signal is set to give adequate time for pedestrians to cross the street. For the walk signal to be requested the button must be within the “window” (on average 20 seconds before the light change), which will then give pedestrian enough time to walk.
If the signal is running in a synchronized corridor (a collection of lights synchronized along a stretch of an arterial), there may be some delay before the walk signal is given while the intersection completes the current signal. Because vehicles need less time than pedestrians to cross an intersection, to have the pedestrian “walk” signal come up during every signal cycle would cause significant traffic delays (which would make you grumpy when you are on the bus or bike or in a car). We know that it is frustrating to press the pedestrian pushbutton “late” in the signal cycle and wait for the next cycle, but this is the only way to ensure adequate time for pedestrians to safely cross the street. It feels so good when you hit the pedestrian crossing button and the signal changes almost instantly to let you cross.
You’ll see another style of button – one that instead of the big silver knob has a smaller button and red light. We install those to help disabled people cross the street. They make a sound so, instead of just lighted signs, blind people can hear when it is safe to cross. The “Cuckoo” sound is for the north/south crossing; the “Chirping” sound is for east/west.
After one of those new buttons was installed, we heard from one four-year-old; he was disappointed that he could no longer see himself make smiley faces in the big silver button. That is a good idea for something to do while you wait for your signal!
(*by the way, the NPR story stated that elevator enginners do say most “close door” buttons do get the door closed faster; but of course it depends when you push it)