Popular Mechanics:

Passengers push buttons to call an elevator, and the elevators respond to these requests. But here it starts to get tricky. At any moment there could be any number of pickup and drop off requests from different parts of the building. With so many options for where to go next, what’s an elevator to do?

Try to picture the perfect elevator system. What makes that system so great? Does it serve the person who’s been waiting the longest? Or always go to the closest call? Where does it make the compromise between speedy service and keeping energy usage down?

Elevator engineers grapple with all these questions, and none of them are as simple as they seem.

For some reason, elevators have always fascinated me. On the surface, they are just a box going up and down but there is so much science, engineering, technology, and sociology that goes on with that box.