Hacker News Reader

Comment by pbj1968 | Hacker News Reader

pbj1968

Pedestrian buttons change the lights. This is easily testable. What an odd analogy.

In many places in the US, pedestrian buttons don't change the lights, certainly not within 1-3 min, if it's a busy or major intersection with lots of vehicle traffic. Also, the controller behavior can change during the day/night depending on traffic volume, or maybe time of day. One time I counted it took the lights 7 minutes to change at a three-lane intersection late at night, even though there were no cars.

https://news.ycombinator.com/item?id=12330251

https://news.ycombinator.com/item?id=17900576#17906527

BBC: "Does pressing the pedestrian crossing button actually do anything?" https://news.ycombinator.com/item?id=6326588

It depends on the light. Some lights don't change unless they sense a car or pedestrian going the other way. Some run on a timer so they change automatically. On others, the light will change but the walk light will not come on if you didn't push the button (these ones drive me insane). Then there's the ones that only activate a chirp for the blind people. Then, finally, there are the fabled buttons of lore that do absolutely nothing. Oh, and some are just broken.

I still haven't come across the placebo buttons though so I'm willing to doubt their existence.

> I still haven't come across the placebo buttons though so I'm willing to doubt their existence.

IIRC the "placebo" buttons, where they exist, were not installed as such, but simply deactivated after the traffic light control system changed, since uninstalling them would be more expensive.

In my home town in Germany (and probably other cities as well, only I've realised I've never really paid attention to that subject while visiting other cities), the little tactile arrow marking the crosswalk direction plus a tactile buzzer for blind people is mounted together with those buttons, so even when a certain direction and its parallel crosswalk always get green by default (and therefore there's no need ever to push a button), a button housing still gets installed for the buzzer and arrow.

The only difference is that those kind of non-buttons are painted a different colour, plus with the older style of buttons that you physically have to push in order to operate a switch, on those non-buttons the push-plate is fixed in place and cannot actually be pushed. (Some people occasionally still try to.) With the newer style of button that operates via some sort of electronic touch sensor and therefore has no moveable parts to begin with, the only distinction might be the colour? (Not sure, because the intersection I regularly pass by on the way to work still uses the old-style buttons…)

> I still haven't come across the placebo buttons though so I'm willing to doubt their existence.

How do you know you haven't?

Oh phooey. It's a longstanding joke that the "Don't Walk" lights don't change to "Walk" any sooner if you press the button. Just like the "close door" button in elevators doesn't make the doors close any sooner than they normally would.

> Just like the "close door" button in elevators doesn't make the doors close any sooner than they normally would.

I recently read an article (maybe even here on HN) that explained this fully.

Basically, in the US, under the Americans with Disabilities Act, the doors must stay open for a minimum time (which depends on some variables). The door close button can only have an effect after that time is elapsed, but in many (if not most bases) the time after which the door automatically closes is set to that same minimum anyway.

My understanding has always been that, at least in the US, it is usually the case that the "close door" button doesn't do anything unless there is a firefighter key inserted and the elevator in fire mode. That's really there to allow a firefighter to manually control the door open/close functions during fire-ground operations where you really don't want the elevator doing things on its own.

There are, of course, always exceptions. Some reading I did earlier suggests that there is some variation based on elevator brand, and possibly even then whims of the building owner (in terms of what instructions they gave the elevator installer about how they wanted things to work). Curiously though the "door open" button does usually pre-empt the (automatic) closing of the door, even in "normal" mode. At least IME.

> Just like the "close door" button in elevators doesn't make the doors close any sooner than they normally would.

I had never thought about this. In Thailand they definitely do close the door sooner, or straight away, and everybody does it all the time.

In europe they usually close sooner, as well. It is allmost as if the world is not made by one standard.

Not necessarily that testable.

For example I used to live near a major junction, for about 18-20 hours per day the buttons have no effect because there is traffic, the junction's computer is adding walk cycles where they fit in its schedule anyway so there's no difference. Testing would show no effect.

Late at night you can see the buttons work, there is no traffic so the junction is left with the fast through lanes green indefinitely, but pressing a pedestrian button causes your walk cycle to run immediately.

On the other hand I work on a University campus, the University would prefer to shut the road through the middle of it, local government said "No" so the pedestrian crossings are set to run very frequently with no penalty delay, meaning most of the day if you push the button you get a walk cycle immediately. During term time it's probably quicker to drive around the campus to the far side than use that road - because somebody will push the button, probably more than once, there are like four crossings with this treatment. So on campus it's very obvious that the buttons work.

Not in NYC

Reply on news.ycombinator.com