I had a dream last week about elevators that go through each other. After a bit of research, I found a few multi-car elevator shaft schematics and patents but they all seem to use a cyclic method of elevators cycling from one shaft and into another, instead of passing through each other.

Here’s my idea:

At least two shafts are required. One shaft is dedicated for people going up, the other is dedicated for people going down. Each shaft will contain many elevator cars, proportional to the number of floors. For an average residential building, 3 cars per shaft should be sufficient. Huge office buildings can have 5-10 cars per shaft.

Considering a single shaft (for people going up), it will work as follows:

People enter an “active” elevator car, the car goes up. Once the last person leaves the car, the elevator car transforms into “inactive” mode: The doors close and the floor collapses outwards to be on the same plane as each side wall. Then, each wall extends outwards one level, effectively allowing “active” elevators below it to pass through it. Once an elevator is in the “inactive” mode, it will make its way down to the bottom floor and wait until the last active elevator departed the bottom floor, at which point the walls will contract, the floor hatch will close, and the door will open waiting for new passengers.

Considerations

• Advantage: Elevator shafts are expensive. Consider a large office building with six to ten elevator shafts, imagine how much money would be saved if there were only two shafts with the same (or better) efficiency.
• Rush hour: This scheme is great for repetitive bursts of people. There should always be a steady stream of elevators, unlike current elevator systems where the shafts tend to accidentally get in sync and you end up waiting while all 4 elevators make their way down from the 40th floor.
• Danger: Collapsing floor instantly screams danger, yes. But with some thorough planning, it should be alright. The elevators cars can use sensitive weight sensors to insure that nothing remains in the elevator when the floor opens. If something refuses to leave the elevator, then the car will proceed to a special extra floor at the top (or bottom) of the building where further effort can be taken without interrupting the rest of the cars.
• Movement mechanism: The classic pulley setup wouldn’t work here. The columns on each corner of the shaft will need some kind of rails which each car can use to traverse and power itself.

In all practicality, it wont happen. But it’s still a cool idea. Who wants to write a simulator?