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True, thought the fact that it took 84 floors for the safety mechanisms to kick in seems problematic. What heuristics did those automated mechanisms have to work through before triggering, and why did they take 84 floors to do it, I wonder.


Clearly, it didn't take 84 floors for the safety mechanisms to kick in. If it had, the passengers would have been in free fall for 84 floors, and suffered the same physical consequences as you would if you jumped off the 84th floor of a building.

Falling 84 floors isn't less dangerous if you end 10 stories above the ground than it is if you end on the ground.


Not strictly true if the elevator braked gradually.


If the elevator braked gradually, then the safety mechanisms kicked in well before the elevator had fallen 84 floors, just like I pointed out above.


Yeah, I was really hoping the article would address this. Were the safety measures designed to kick in at the 11th floor, or were the passengers just lucky that they were at the 95th floor instead of, say, the 80th floor when the elevator took 84 floors for the safety measures to stop the elevator?


My guess is that there's some sort of velocity/acceleration threshold. So since the elevator car was still attached by other cables it didn't fall fast enough to trigger the mechanism earlier.


That, and this was an express elevator, so safety features have to kick in at higher speed.

Safety features also can’t decelerate the cage too fast. If, say, the elevator fell from floor 70 to floor 40 before safety features kicked in, it makes sense to use most of the remaining space for deceleration.


As someone who was in an elevator that dropped ~20 floors out of nowhere and then functioned normally (Zeckendorf Towers), I imagine that's true.




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