The appearance of bridges might change but I suspect that the underlying structural components are much better specified than what we have with software. While

The appearance of bridges might change but I suspect that the underlying structural components are much better specified than what we have with software. While I don't know the specifics for bridges, I have seen the specifics for the joist industry (those metal rails with Ws inside them that you see when you look up at the ceiling in a Walmart). There is some design work that an engineer needs to do for any given job. However, they pick the type of joist, material, and wield (etc) based on a book that publishes weight tolerances. And those numbers come from someone taking a joist out someplace and dumping weights on it until it collapses. We just can't do the same thing with software. It's not even clear what kind of weight we would be dumping on software. Human comprehensibility? How do you measure that?