bostontrainguy wrote:Thinking out loud, I wonder what this means exactly:
"Apparently, these railcars failed the buff strength test at 798,000lbs when FRA's requirement is 800,000lbs."
Did the cars buckle somewhere a few inches? Did the entire car implode on itself? I would really be interested in knowing exactly what is considered a failure at 99.75% compliance.
In a sense, it doesn't matter. Most likely a failure like this starts as a slight crumple and depending on how quickly the testing machine can be shut down, would crumple in an accelerating fashion.
Compare to pushing on the to of a straw, once it starts to collapse, it happens very fast.
And as Nasadowsk said, creating waiver can set a bad precedent. If you really have an issue with a standard, the solution is to develop a new, better standard (or at least argue the current one is not good enough).
In some ways (it's a a bit more complex) the Challenger disaster was the result of continually allowing waivers to the O-Ring specs because they thought they understood the phenomenon well enough.
They didn't.
Keep in mind they DESIGNED it for 800Klb... So it's not just "give us a waiver" but really "figure out WHERE we went wrong!" Designs like this in theory should be developed well enough that testing matches expectations. The fact that it failed suggests that something is wrong with the theory and design and until you know exactly what that is, you probably shouldn't allow a waiver.
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