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@jasoncrawford | |||||
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This footnote in McCullough's *The Great Bridge* blew my mind. As late as the 1880s, we still didn't know how to build bridges! We would put them up, and many would just collapse. pic.twitter.com/6vjfkQ482H
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Jason Crawford
@jasoncrawford
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13. sij |
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Those that stayed up often seemed to be overbuilt. So you were really depending on the intuition—and the risk tolerance—of the chief engineer.
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Jason Crawford
@jasoncrawford
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13. sij |
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How did this persist for so long? How did we get Bessemer steel, electric generators, transcontinental railroads, antiseptics, power looms, adding machines, the telegraph, and canals that divided continents… before we figured out how to build bridges that don't collapse?
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Jason Crawford
@jasoncrawford
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13. sij |
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Read that footnote again. Forty bridges a year! That's almost one a week. Like the Sunday newspaper could almost have a regular “bridge collapses” section.
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Jason Crawford
@jasoncrawford
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13. sij |
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And bridges are something we've been doing for a long, long time. I think even pre-state societies build simple bridges. The Romans must have built some big ones, no? Did theirs collapse too?
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Jason Crawford
@jasoncrawford
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13. sij |
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Plus the math here ought to go back to Newtonian physics, I would think. Basic concepts of force and mass… some of the first to be quantified. Why wasn't there more theory to be applied here?
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Jason Crawford
@jasoncrawford
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13. sij |
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Maybe the problem wasn't in making a bridge that could stand, but in all the many random things that could bring it down.
Bridges are subject to wind and water, and fluid dynamics is terribly complicated.
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Jason Crawford
@jasoncrawford
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13. sij |
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Or to take another example, I think I recall hearing about a failure due to iron becoming brittle in extreme cold, not necessarily something you could predict without a lot of materials science.
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Jason Crawford
@jasoncrawford
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13. sij |
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Also I have to admit I have no idea how many total bridges there were in the country at the time, or how fast they were going up. So I don't even know the order of magnitude of the failure rate here.
Still, forty a year!
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Jason Crawford
@jasoncrawford
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13. sij |
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Anyway, gotta be a fascinating story here. Definitely will cover this in a future @rootsofprogress post!
Subscribe to get it when I do: rootsofprogress.org/subscribe
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Jason Crawford
@jasoncrawford
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18. sij |
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So here's an example of a bridge collapse. Diagnosis: the engineer “had not calculated his wind loads accurately” pic.twitter.com/uwtmofMx9U
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