Why does the elevator skip my floor?

Usually because it's going the other way: it serves every call in its current direction first and picks you up on the way back. It also skips you if it's full, a feature called load bypass, and in a building with several cars the dispatcher may have given your call to a different car.

Does pressing the button again make it come faster?

No. A landing call is one request per floor and direction. The first press registers it with the dispatcher, and every later press asks for the same thing.

Should I press both up and down?

It makes things slower. The car going the wrong way stops for you too, which adds a stop for everyone aboard, and you can't ride it your way. Elevator engineers list it among the habits that make real buildings slower than their simulations.

What is destination dispatch?

A lobby keypad or screen where you choose your floor before boarding, and the system tells you which car to take. Grouping riders going to the same floor means fewer stops per trip. Schindler built the first such system, and TK Elevator and other makers now sell their own.

Live model · Elevators

How Elevators Actually Decide Where to Go

An elevator serves every call in the direction it's already going, then turns around. So if you want down while it's heading up, it can roll right past your floor, finish its trip up and come back for you. On the stage you wait 74 seconds while the riders going its way waited 0 to 14.

One car on collective control, second by second

One car, waiting at G. 3 riders call it over the first seconds; at 2 s you press the down button on floor 4. The car takes 2 s a floor and 8 s a stop, and it runs on collective control: it serves every call in the direction it's going, then turns around.

StopCollective control

Your floorYou want to goYou call at (seconds)Other riders

Time0 sCaridle at GYour wait–

The building

The car's floor, second by second

Riders

Who	Trip	Called	Picked up	Waited
rider 1	G → 8	0 s	0 s	0 s
you	4 → G
rider 2	G → 6
rider 3	2 → 9

CH4 car A
CH1 you

Watch the Python behind this model run, line by line

How to read the stage

One car in a 10-floor building, 2 seconds a floor and 8 a stop. Three riders call from G and floor 2, all going up; at 2 seconds you press down on 4. The car passes 4 at 32 seconds without stopping, drops everyone off, turns at 9 and picks you up at 76 seconds. The chart is the car's floor over time, your floor marked.

Why it passes your floor

This is collective control, the rule most elevators run. Going up, the car stops for riders getting off and for up calls; down calls wait for the way back, so nobody rides the wrong way first, which elevator engineers treat as unacceptable. Timing matters as much as direction: calling up from floor 3 at 30 seconds, you'd wait 0 seconds. Two seconds later, 46.

Many cars, one dispatcher

With several cars, a dispatcher picks which car answers each call. The second stage sends 40 riders up from G in a morning rush to 3 cars. Sending each call to the nearest car gives an average wait of 29.9 seconds. Sending it to the car with the lowest estimated arrival, counting the stops it has already promised, gives 28.3.

Three cars, three dispatchers, the same 40 riders

40 riders arrive over the next few minutes (morning rush). 3 cars, each on collective control, and a dispatcher: each landing call goes to the car the fewest floors away, whatever it's doing.

StopGroup collective: nearest car

TrafficCarsDispatcherSeed

CH4 car A
CH2 car B
CH3 car C

Watch the Python behind this model run, line by line

Destination dispatch

Newer lobbies ask for your floor before you board, then name a car, grouping riders going to the same floor so each car makes fewer stops. On the same 40 riders it cuts the average wait to 21.7 seconds and the average trip from 71.5 to 59.7. The longest single wait rose to 93 seconds: a rider isn't always given the next car to arrive.

What the model leaves out

Every stop here takes 8 seconds and every floor 2, whoever gets on. Real cars speed up and slow down, doors reopen, people hold them, and dispatchers re-plan as calls arrive; Peters warns that simulated performance often isn't reached on site. Riders follow a seeded schedule, each car holds 8, and a full car skips landing calls, as real ones do.

Questions

Why does the elevator skip my floor?: Usually because it's going the other way: it serves every call in its current direction first and picks you up on the way back. It also skips you if it's full, a feature called load bypass, and in a building with several cars the dispatcher may have given your call to a different car.
Does pressing the button again make it come faster?: No. A landing call is one request per floor and direction. The first press registers it with the dispatcher, and every later press asks for the same thing.
Should I press both up and down?: It makes things slower. The car going the wrong way stops for you too, which adds a stop for everyone aboard, and you can't ride it your way. Elevator engineers list it among the habits that make real buildings slower than their simulations.
What is destination dispatch?: A lobby keypad or screen where you choose your floor before boarding, and the system tells you which car to take. Grouping riders going to the same floor means fewer stops per trip. Schindler built the first such system, and TK Elevator and other makers now sell their own.