2 ms·

Why would slumping or buckling but not-quite-collapsing be a functionally better outcome than complete failure? In both cases, the sheer size of the physical ch

Why would slumping or buckling but not-quite-collapsing be a functionally better outcome than complete failure? In both cases, the sheer size of the physical changes is going to lead to forces that humans won't survive, so there's no benefit there. In both cases, the bridge is going to have to be completely demolished before rebuilding, so there's no benefit there. A bridge that could stand the loss of a single support pier without any significant collapse would obviously be preferable -- but that's a big ask. I'm not a structural engineer, but I am aware of scaling laws [1] and it feels to me that those scaling laws are going to mean that increasing the margin of safety by x is going to increase costs by x^n. For a project like this one, where cost was apparently the deciding factor over a tunnel, that matters. [1] https://galileo.phys.virginia.edu/classes/609.ral5q.fall04/LecturePDF/L14-GALILEOSCALING.pdf https://galileo.phys.virginia.edu/classes/609.ral5q.fall04/L...

Dalewyn 3y ago
>Why would slumping or buckling but not-quite-collapsing be a functionally better outcome than complete failure? Well for starters, there's a better chance of less (or ideally no) people forced to get their feet wet and go missing or die from drowning or hypothermia.
- gnfargbl 3y ago
  The specific point I'm making (in the sentence following the one you quoted) is that no, there is not a better chance of those things. If a bridge of this size is going to fail in any significant way, it is going to lead to loss of life. The broader point is that attempts to blame the bridge designers here are misplaced. It really isn't reasonable to have hoped that they could design a structure that could cope with this kind of failure, within the cost constraints that they had. And cost constraints were a real thing for the designers of this particular bridge.

Dalewyn 3y ago

>Why would slumping or buckling but not-quite-collapsing be a functionally better outcome than complete failure? Well for starters, there's a better chance of less (or ideally no) people forced to get their feet wet and go missing or die from drowning or hypothermia.

gnfargbl 3y ago
The specific point I'm making (in the sentence following the one you quoted) is that no, there is not a better chance of those things. If a bridge of this size is going to fail in any significant way, it is going to lead to loss of life. The broader point is that attempts to blame the bridge designers here are misplaced. It really isn't reasonable to have hoped that they could design a structure that could cope with this kind of failure, within the cost constraints that they had. And cost constraints were a real thing for the designers of this particular bridge.