I’m talking the ones across a road, not at a junction.
Invariably, you press the button, and instead of the light turning red straight away there is a delay of (what seems to be) about a minute. Why is this?
I could maybe understand this on a busy road where you don’t want a busy crossing constantly interrupting the traffic flow, but this happens when the lights clearly haven’t changed for several minutes.
I heard somewhere that most traffic light crossing buttons don’t do anything.
Clearly that doesn’t apply to the case in the OP, which is a demand-driven crossing not at a junction.
I always assumed the delay was to stop the chance of someone pushing the button immediately after the traffic light turns green (for the vehicles), which would make them stop again if there were no built-in delay. Now the obvious counter to this is that it should not delay if more than a given time has passed since the traffic saw a green light. My guess is that it is easier (= cheaper) just to have the delay every time the button is pressed.
Usually pressing the button inserts the walk cycle after the current cycle, and the current cycle generally has a minimum length.
You have to wait for the elevator to reach your floor before you can cross the street.
What makes you think that pressing the button will cause any immediate action? Would that be a good idea if the light just turned green, and a second later, it turned back to red because you pressed the button?
In many signal cycles, pressing the walk button only sets a flag in the control sequence that says, “when the next cycle changes, turn on the walk light along with the green in the appropriate direction.” It may also lengthen that subsequent cycle to allow for pedestrian slowness across wide intersections. but it doesn’t bring traffic to a halt just because you are a pedestrian.
The type of crossing he’s talking about does not have a traffic intersection so there is no cycle for the lights. They are always on green until someone pushes the button to cross, so they do bring traffic to a halt because just you’re a pedestrian. Allowing time for traffic to flow in case the light had just turned from red to green makes the most sense to me.
OK, in that case there probably is a minimum wait time after the ped button is pressed. Could be for several reasons. Maybe the idea is to try to accumulate more than one pedestrian before the light changes. Maybe there is some synchronization with nearby lights. Maybe the traffic green is designed to be at least for a minimum time before changing. Not all signals are set up the same and can be adjusted for local (and time of day) conditions.
If it changed right away, it would kinda be bad for any cars already too close to stop. Better to make you wait a minute.
Well, presumably it would go yellow (or amber, as they say in the U.K.) first, like traffic lights always do before going red, for just that reason.
Could the delay the OP is talking about simply be the period while the light is yellow? Maybe it does go yellow as soon as you press the button, but it does not go red and allow you to cross until it has been yellow for a while.
I like this explanation the most – it was written by a retard programmer to be the simplest implementation possible.
Or maybe it’s something like… “well, if it turned red right away it’d be too much fun, and kids would press it just to get a kick.”
What the OP seems to be expecting is a crossing where a pedestrian gets automatic priority over road traffic. We have those in the UK, they are called zebra crossings. Unlike in many parts of the world such crossings here are respected by the vast majority of drivers who will stop for pedestrians waiting to cross or already on the crossing. Crossings controlled by lights are used where traffic flows mean that a zebra crossing could create congestion and so pedestrian flows need to be managed too.
All that said I think the observations of the OP are faulty in two respects. Firstly waits of a minute are somewhat exaggerated, except maybe at junctions where the lights control normal traffic flows in addition to pedestrians. Secondly I know of several pedestrian crossings where pressing the button may at times result in an almost instantaneous change, dependent on time since the last change and possibly traffic levels measured by infra red motion sensors mounted on top of the poles.
No, not here. I’m talking about a sequence that goes:
Push button, wait.
Wait a bit more.
Start getting impatient and risk crossing anyway.
Then lights change to amber, then red.
I think these are an endangered species. They’re being replaced with crossings with traffic lights (what we call a pelican crossing).
Ok maybe a minute is an exaggeration, but even 30 seconds is long enough to start getting annoyed and risk crossing anyway. I don’t get why there should be any delay at all if the crossing hasn’t been used for several minutes.
None of the crossings in my area change instantaneously. One actually used to and it worked great, but then it was reprogrammed and the delay came into effect.
I think if you ask yourself why zebras are being replaced with pelicans you may get closer to answering your own question. [hint: last sentence of my first paragraph above]
My totally unsubstantiated guess is that the rationale is connected to the expected behaviour of subsets of pedestrians
[ul]
[li]If the light (for the vehicles) immediately turned to yellow more children (and immature persons of any age) would press the button just to force one particular approaching vehicle to stop. [/li]That’s at least much more difficult to time if there is a delay, also such persons don’t have that much of an attention span.
[li]If the reaction (at least the vehicle lights turning yellow) were immediate, some pedestrians would acquire the habit of pressing the button then stepping on the crossing without looking (as this would work most of the time, in this scenario.) Some of them would be hit by cars which are too near to stop.[/li][/ul]
We have a crossing near us (in the UK) which is instant, providing (1) no traffic is nearby, and (2) it’s been a while between crossings.
You push the button and the lights change right away.
In fact, as it’s on a bend in the road quite often you’ll push it and a car will have to drop anchors fairly sharpish to make the stop (partly because they drive too fast on that road anyway).
This - especially the second. I go through about three pelican crossings on my way to work. At two of them, if I see someone pressing the button then I know that I’m safe to go ahead at the speed I’m going (providing they’re on their own of course - why do people press the button when it’s already been pressed?!). The other goes to red the moment the button is pressed, so I have to watch out for all the kids walking near it to make sure they don’t hit it as I get close.
Happened to me on my driving test too - drove out of the testing station, switching up the gears and trying to relax then ended up doing an emergency stop as someone pressed the button and created an instant red. I still passed, but the examiner did say I scared him!
Exactly. In my experience, there is only a delay if the crossing has been recently operated. If it hasn’t been operated for a while, then the lights will change almost instantly.
I think the OP may be mixing up two types of crossing - the one described above and one which also incorporates timed signals at a junction. In most cases with the latter type, pressing the button does nothing - the red and green man signals light up as appropriate during the cycle regardless of whether you push the button or not, and the cycle timing is unchanged. So it stands to reason you will lilely have to wait.
One addition to this - many pedestrian-only crossings (not at a junction) have sensors embedded in the road surface (you can see a criss-cross pattern of tar lines where the wires have been laid). I think these are used to incorporate an extra delay if there is heavy traffic.
My own observations in my local town has been that where there are traffic lights for the sole purpose of allowing pedestrians to cross the street, pushing the button makes the lights go orange then red so you can cross.
Where the traffic lights exist at an intersection, where the main purpose is controlling the flow of traffic along the two intersecting streets, pushing the button makes the pedestrian light go on in line with the pre-determined timing of the traffic lights changing.
Don’t the pedestrian lights come on anyway? They certainly do in the UK, whether you press the button or not. At any point in the cycle where it is safe to cross, the green man will be showing; otherwise the red man will be.
Only at non-junction lights does the red man not appear until you press the button.
