5 reasons why you have to wait for the elevator

We get it. Waiting is the hardest part. Once you touch the elevator button it seems like you just wait. You have to wait for the door to open. You have to wait for everyone else to get on and off. You have to wait for the doors to close. The truth is a lot happens after you touch that button and before the doors open. Jesse Dunietz of Popular Mechanics does a stellar job of explaining The Hidden Science of Elevators. But if you don’t want to wait to get to the end of the article, here are five main points.

1. Elevators use algorithms (step-by-step, machine-controlled procedures for accomplishing a task) to determine where the elevator goes and when. Elevators are programmed to respond to button pushes or requests for service. There can be many requests or button pushes made at once so the elevator has to “decide” where to go using an algorithm.

2. When it comes to elevator routing, decisions have to be made based on what Dunietz refers to as the "pain index". Simply put, which elevator passenger's "pain" from waiting so long takes priority? Is it the guy who's been waiting the longest in the lobby? Or is it the crowd forming on the seventh floor? Would passengers rather wait one minute and ride for 30 seconds or vice versa? Elevators operate under speed and time constraints. A great deal of analysis and mathematical computation goes into optimizing elevator performance. If you are into those kinds of details, you can read more here.

3. In low- and mid-rise buildings, elevators can operate using the approach of collective control. If a passenger is inside or ahead of the elevator that is traveling upward, collective control tells the elevator keep traveling in that direction. Once those passengers have exited, the cab switches directions to take the other passengers down or stops and waits for a call.

4. In taller buildings that have more passengers, things get more complicated. Engineers have developed controllers (like the "brain" of a computer) that can optimize performance to adapt to tenant demands. For example, they can dedicate elevators to serve certain floors, provide priority access and send more elevators to specific floors at periods of high demand.

5. The most advanced system are destination dispatching ones like AGILE. This advanced dispatching system directs passengers to the elevator that will get them to their destination in the shortest travel time. By grouping people together based on the floor they are traveling to, the number of stops is reduced, thereby improving the efficiency of the building's elevator traffic. With these types of systems, there are no buttons to press; passengers just use a kiosk to select their floor and the system tells them which elevator to board.

Thanks to learning systems and evolving algorithms, repeatedly pressing elevator buttons really doesn't speed things up. Next time you consider blaming an elevator for your tardiness, remember that the machine is learning more with every trip up or down (and maybe don't stop for coffee next time).