April 16, 2008
Engineering Department
Elevator of Death...Or Not
When it comes to elevators, our biggest fear is that the cable will snap and the elevator will fall to the bottom of the shaft. People debate whether there is anything you can do to save yourself---jumping just before you hit is the most popular suggestion. A few years ago, Mythbusters did a test, and the result was not pretty. Jumping doesn't help.
Elevator engineers could have told you that. If our legs were powerful enough to jump hard enough to counter the speed of the fall, they would also be powerful enough to absorb the impact. Heck, if our legs were that strong, we'd all be able to jump very high. Apartment buildings up to about five stories wouldn't need stairs---people would just jump up onto their balconies from outside.
On the other hand, I've long suspected that such elevator falls are extremely rare. Although hoists of various kinds go far back in history, we didn't start putting passenger elevators in buildings until after Elisha Otis invented a mechanism to prevent elevators from falling. Modern elevators are defined by their inability to fall. My guess was that fatal falls happened less than once a year, at least in this country.
According to a fascinating article about elevators by Nick Paumgarten in the New Yorker, I'm way off, but in a good way: For a long time, there was only one known free-fall incident in a modern elevator. It happened in 1945. And it happend when a B-25 bomber struck the Empire State Building in the fog. The impact cut all the cables on two elevators, which fell all the way to the bottom. There was only one person in the elevators at the time, an elevator operator. She was hurt bad, but she survived.
(The terrorist attack on the World Trade Center---which also involved airplanes hitting buildings---killed a bunch of people in elevators, a few of whom probably died from falls down the shaft.)
If you've ever seen the top of an elevator, you know there are a bunch of cables holding it up. Every single one of those cables can hold the entire weight of the fully-loaded elevator. Many elevators also have brakes that lock the elevator to its rails, so even a loss of all the cables wouldn't make it fall. Finally, there's a hydraulic buffer at the bottom of the shaft to cushion the impact.
For all practical purposes, nobody ever dies in an elevator fall. In fact, of the 20 or 30 elevator-related deaths each year, most of them are maintenance accidents---technicians leaning too far into the shaft or getting caught between moving parts.
However, if you still want your elevator rides to have some thrills, there are always the hazards of elevator doors to worry your mind, such as people stepping blindly through doors that open into empty shafts or being strangled by scarves caught in the doors. If you want something really scary to spice up your elevator rides, sometimes the door-open safety mechanism fails and an elevator suddenly moves while people are getting in or out. The results are often gruesome, and sometimes end with the elevator passengers riding up a few floors with a severed head.
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Fascinating article. Thanks!