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
“when it doesn’t seem to make a difference ”
I think you’d first have to first get from “doesn’t seem to” to “doesn’t actually”…?
The ones near me I’d guess have a particular place in their cycle where they’ll allow folks to cross. When you press the button, it is just telling the signals to give pedestrians time to cross when that point is hit next. If the button isn’t hit, the cycle would just continue normally.
If you hit the button, 3 seconds before that point in the cycle, then it will feel like you were given some amount of preferred treatment as a pedestrian. if you hit it 3 seconds after, then you are waiting for virtually the entire cycle and it’ll feel like the traffic light is punishing you for not driving a car.
It might behave differently depending on time of day. A lot of signals change to on demand only at night. Also without button the traffic may stop normally but the crossing signal may be short or non existent.
It makes a big difference in the light timing. The length of time a ped signal is up is based on the length of the crosswalk, usually 3.5 feet per second. Depending on the width of the road, the crossing time could be anywhere from 15 seconds to 60 seconds or more. And the traffic lights will be green this whole time.
The time a light is green is usually based on the traffic, especially for the small side streets. The light will only come up if the intersection detects a car waiting, and it should only stay green long enough to clear out the line of cars. If there’s only one car waiting, it’ll be green for a minimum time of about 8 seconds, then go yellow and red. The idea is to get back to the main road being green as soon as possible, since that’s where all the traffic is. However, if someone pushes the ped button, now it’s gonna be stuck in green for 20, 30, 60 seconds, even if there’s only 1 or 2 cars. It’s a giant waste of green time, at least from the point of view of the motorists. So the press of a button is the difference between an 8 second green and a 40 second green, along with an equivalent red time for everyone else.
If there’s no button, then there is always a Walk signal regularly inserted into the traffic cycles.
If there is a button, then there is no Walk signal in the light cycle until the button is pressed, and then a walk signal is inserted into the cycle once.
This’ll differ depending on the country and place.
Some buttons are fake.
Some lights don’t give pedestrians any green light unless the button is pushed first.
Sometimes a default cycle is used and the button only decides whether you’re in the cycle or not.
Sometimes the intersection has a full dynamic system that takes into account time of day, weather, traffic, other nearby intersections, and the amount of desperation they see in your face.
Sometimes cyclists have a button but also magnetic ground loops so you don’t really need go press as your bicycle is already registered by the system.
Which of these systems is used in your place of residence and whether pushing the button actually makes a difference is impossible to say for us. Maybe a nice experiment could be to grab a chair, a stopwatch, and try to spot what patterns it follows
Some places, it definitely does matter. I can think of a few pedestrian crossings near me that don’t change unless the button is pressed.
Some places, it matters but only some of the time. If it’s a busy junction, the lights might have a rush hour setting that skips the pedestrian crossing unless the button is pressed, but the rest of the time it gets included as part of the cycle.
And in some places (like city centres), the button controls the pedestrians. Studies have shown people will wait longer for the green man (WALK sign, white man, whatever) before they just walk into traffic if they (or someone else) can press a button. So, if you’ve got a busy junction that needs precise timing to reduce congestion but pedestrians keep screwing it up by ambling into the road, just stick in a placebo button that illuminates a “Wait” sign.
Colose to me is a crossroads that allows diagonal crossing too. The diagonal crossing is time dependent (rush hours). Don’t press button don’t get diagonal crossing.
Part of traffic/road design to optimize flow. If you’re in downtown, you probably want the light to switch at fairly set intervals because there’ll always be traffic. In that case the crosswalk button probably does little if anything at all. Maybe it’ll speed up the change by a few seconds.
In a random crosswalk with less foot traffic or wide lanes, they probably actually make a difference . Think of those 8 lane main roads in the suburbs. There’s probably less foot traffic and when there is it takes people longer than the usual time to cross. The 99% of the time when no one is pressing the button, the time is set to optimize traffic flow. If the button is pressed it’ll optimize pedestrian safety and give extra time. I’ve actually seen this. Green light for one direction, the pedestrian sign will go green but with only 10 secs on the countdown. Press the button for the other direction and it’s 30 seconds.
Base on time of day or the road some lights just don’t change at all unless a sensor is set off by a car or the pedestrian button is pressed. If you drive around late enough you’ll notice some lights at empty intersections will be static until you or someone else pulls up close enough.
It’s car-centric, hostile pedestrian design. If a pedestrian is hit when walking against a stop signal, despite it being green in the same direction, it will be their fault just because they didn’t hit the button.
On most it’s a placebo. It makes you feel like you’re doing something positive. On some where there is only occasional pedestrian traffic it does actually signal that someone is there looking to cross and triggers the light to give a walk signal at the next cycle opportunity.
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