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Tuesday, April 08, 2008

Elevator Musing

I've often wondered about the principles behind elevator programming. (A system whose inner workings are opaque, encountered often, and usually at moments when you have time for idle thoughts -- a recipe for excess contemplation.) Does the elevator brain sometimes tell a car with several floor buttons pressed to bypass a call if another empty car is nearby, or are they not that smart? During off-hours, do the elevator cars congregate at the lobby level, or do they fan out strategically across the floors to serve potential calls as speedily as possible? Or do they lazily park themselves wherever someone last got off?

So I was pleased to stumble across this nice blog post about elevator control design. The most shocking revelation: Some new buildings are using using a system called "destination-based dispatching." Instead of pushing a button that tells the elevators "I want to go up," you actually key in your floor. The elevator brain groups people by destinations, and a screen will tell you which elevator to get in. You do not press any buttons upon getting in the elevator, just get off when it automatically stops at your floor. (You can try this demo if you like.)

As someone who has found himself trying to think of ways to program elevators to be more efficient, I can only imagine the deep, burning desire of a professional elevator control engineer to make this sort of quantum leap in efficiency. (Not only as a professional achievement, but also for the sense of striking a decisive blow in the battle against the entropy of the universe.) But it also runs into some real-world problems. In a separate post, the same blogger I linked to above describes his first experiences with destination-dispatched elevators in the new New York Times building. One, it turns out the cars have no controls on the inside. You are totally in the hands of the (hopefully) benevolent elevator brain. I guess the actual level of control you have in a normal elevator is not that much greater, but being in an automated delivery box would be disconcerting to me regardless. Two, the experience is made more disorienting by the fact that the elevator does not reveal its current location, just a list of upcoming stops. The blogger notes that people sometimes accidentally get off a stop prior to their destination. More intriguingly, the elevator expert he talks to also notes that people may get frustrated seeing others get on elevators first, or hearing elevators go past without stopping. The system may technically be more efficient, but because people do not understand its reasoning, they may not feel any better because of it. I'm reminded of ReeD's post a while back about trying to figure out when a machine's smarts get in the way.

Meanwhile, Schindler, a manufacturer of "vertical transportation solutions," has recently announced that they are "[taking] destination dispatching to a new level." (You'd think they'd be tired of the puns after all these years.) Their new system integrates destination dispatching with those RF ID cards everyone is carrying now -- you swipe your card, and the elevator knows which floor you're likely heading for, as well as which floors you're not allowed to access. "Not only does the smart elevator know in advance where the passenger needs to go, it also knows who the passenger is and personalizes the trip accordingly," according to Schindler. ("Sir, I hear you're feeling a bit nauseous from the lunch buffet -- I'll be careful not to jostle.")

Not like we're in any danger of getting this at my office. But in any case, for conservation and fitness reasons, I've been taking the stairs. Expect a lengthy post about stairway design sometime soon.


Andy said...

We had destination-based dispatching at my office building in New York, although it was only partial. You would punch your number in the lobby, but from all other floors you'd just hit up/down.

Also, the cars had buttons, so if you held down your destination until the car reached its first programmed floor, you could bypass the menu of floors outside.

To complicate matters further, we were on the third floor, but the stairs were at best moderately convenient. This basically meant that every time I waited to get on the elevator going up, I was pretty sure that I could have walked faster if only the stairs had been completely accessible.

If I'd been on a higher floor, I'd probably have always hitched a ride on a mostly empty elevator, assuming I could successfully request my floor as the second or third destination. In other words, the implementation invited people to game the system, probably eliminating the usual efficiency.

teague said...

That does sound like a few too many wrinkles standing in the way of a smoothly-functioning system.

The inaccessibility/unpleasantness of stairs is a pet peeve of mine. If architects designed them as a welcoming, accessible feature of the building, they'd get used a lot more...and elevators use a lot of electricity.