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Both as a kid and as an adult, I've encountered elevators lined up next to each other, or single ones, which have two buttons on each floor (outside of the elevator):

^

And:

V

Pressing one of them makes it light up. Not understanding what the arrows/pointers symbolize, I always pressed both. They would stay lit until the elevator arrived. I have no idea if I made myself wait longer or caused issues for others by doing this.

As far as I can tell, there is nothing whatsoever which explains what the buttons do. No instructions of any kind. This was apparently considered so obvious that even the dumbest person could figure it out. But clearly, they had not thought about me...

To me, the most likely way in which they are meant to work is:

Pressing "up symbol" means "I want to go up", and pressing "down symbol" means "I want to go down". That is, you are just implying that you want it to arrive at your floor ASAP, but the information you input is where you want to go. Correctly telling the elevator system this information supposedly helps it perform optimally for everyone, and potentially even shortens your own wait time.

However, if that's what it means, then why am I allowed to press both buttons, which then both stay lit? Shouldn't it then disable the other button since you pressed the first? Since you can press both, that gives zero useful information to the elevator system. Unless that means that there are people standing in line who want to go up and others who want to go down... but that sounds too complex of a setup.

Another possible interpretation is:

Pressing "up symbol" means "I want the elevator to go up, stopping at my floor, because it's currently below my location", and pressing "down symbol" means "I want the elevator to go down, stopping at my floor, because it's currently above my location". Since each person can see where the elevator currently is (on a separate series of lights, above the elevator), this is quite possible, albeit perhaps slightly less likely.

So... which is it? Or does it work in some entirely different way? Am I the only person in the world who manages to get confused by those buttons?

Wouldn't the best design be to have just one button per elevator entrance which simply means "bring the elevator here ASAP"? At least that cannot be misunderstood.

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The elevator control system stores various bits of information in a logical fashion. The system will be optimised to maximise the utility of the lift. This generally means moving the maximum number of people to their desired destinations in the minimum time.

The logic is smart.

  • If someone on the tenth floor presses the ▾ button the elevator will run to the 10th floor.
  • If someone presses the ▴ button on an intermediate floor before the elevator passes that floor it will stop to collect the passenger.
  • If someone presses the ▾ button while the elevator is going up the system will ignore the request until the elevator is going down.

Pressing "up symbol" means "I want to go up", ... That is, you are just implying that you want it to arrive at your floor ASAP, but the information you input is where you want to go.

Yes, ASAP is always assumed subject to the first-come, first-served sequencing.

Correctly telling the elevator system this information supposedly helps it perform optimally for everyone, and potentially even shortens your own wait time.

Correct. You must have caused a lot of delay through your life so far. Hopefully we can avoid further loss of life.

However, if that's what it means, then why am I allowed to press both buttons, which then both stay lit? Shouldn't it then disable the other button since you pressed the first?

No. You may want to go up and someone else wants to go down. The elevator will stop and the passenger needs to determine which direction it is running before stepping in.

Since you can press both, that gives zero useful information to the elevator system. Unless that means that there are people standing in line who want to go up and others who want to go down... but that sounds too complex of a setup.

Nope. That's the way it works. Yes, elevators are complex.

Another possible interpretation is:

Pressing "up symbol" means "I want the elevator to go up, stopping at my floor, because it's currently below my location", and pressing "down symbol" means "I want the elevator to go down, stopping at my floor, because it's currently above my location". Since each person can see where the elevator currently is (on a separate series of lights, above the elevator), this is quite possible, albeit perhaps slightly less likely.

No, the user doesn't have to do the optimisation. The control logic does that.

Am I the only person in the world who manages to get confused by those buttons?

Probably not.

Wouldn't the best design be to have just one button per elevator entrance which simply means "bring the elevator here ASAP"?

No. Imagine everyone leaving the apartment to go to work in the morning. The optimum sequence is for everyone to press the down button when they arrive at the lift, let the lift run non-stop to the top and then pick everyone up on the way down.

At least that cannot be misunderstood.

Ummm ...

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  • $\begingroup$ Most elevators have indicators that inform those waiting which way the car is going. They may be above the door, or the call button gets extinguished. For instance, if both call buttons are pressed, a down car will cause the down call button lamp to go out and the up call button will remain lit. $\endgroup$ – Phil Sweet Mar 24 at 20:42
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The up arrow button is for when you want to go up in the elevator. Then down arrow is when you want to go down. If you press only the one you want, the elevator will stop on the way up or down only, instead of opening once for one way and then again when it passes the other way.

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They are just to tell the elevator which way you want to go. If you want to go up then push the up symbol ^, then, if the elevator is already on a trip going down past your floor, it won't stop. It will stop on its way back up.

This saves a lot of time. You don't get an elevator going in the wrong direction, and those already on the trip don't have to stop at every floor where someone wants to get a trip, it stops only for those going in the same direction

You can push both because you might not be the only want that wants to use the elevator. If someone else wants to use it, they might want to go in the opposite direction as you and in that case the would push the other button so that both are lit up.

It's polite to only push the button for the direction that you want to go. It's polite to also wait until the elevator is going in your direction to get on, even if it stops for the person going the other direction, wait for it to come back in your direction. We all like our personal space, so only being in the elevator when you need to is polite

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I seriously doubt anyone else has thought like that.

  1. What do the symbols mean? ^ means 'I want to go up', and v means 'I want to go down'.
  2. What if the lift car is below me and I want to go down, would I press the ^? No, you don't always get indications of where the lift car is currently located, so if you don't know where it is, how could you input a request for it to move towards you based on where it is?
  3. Why do both buttons stay lit? Because there could be 2 (or more) people waiting for a lift car, and each/some want to go in different directions...
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  • $\begingroup$ Welcome to Engineering! I have edited some unnecessary personal comments from your answer. Please read our Code of Conduct to better understand the format expected for questions and answers on this site. $\endgroup$ – Wasabi Apr 24 at 1:19

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