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Comment by Xylakant | Hacker News Reader

In the town where I’m from in Germany, exactly this happened: a major bridge was unsafe - one of two major roads leading to the crossing of the river rhine. It was closed and torn down, replacement will take a few years. In Berlin, one major river crossing was closed because it was unsafe, then torn down and replaced. Another was severely impacted and partially closed, it’s now replaced with a temporary bridge. Full replacement is expected in a decade or so. People adapt. Life goes on. It’s better than having the bridge collapse with people on it.

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This very thing occurred in PGH with the Greenfield Bridge[0]. This caused significant disruption because the bridge spans a major highway to the eastern suburbs. Of course, the infrastructure issues with that bridge were rather obvious, since chunks of concrete would fall on to the highway (necessitating netting to be installed).

[0] http://greenfieldbridge.otmapgh.org/

Anything is better than people on a collapsing bridge, obviously. But you can only fence it off when you know its too bad. Checking that can be very expensive. So if you just don't know which of 450 bridges are bad, what do you do? Fence them all of and spark at least outrage? Safest option. Finding out what to do is already expensive

You can start off with warning signs. I doubt bridges would collapse if pedestrians or bicyclists use them but sings could fend traffic off.

Second, the size of the vehicle is important. Larger vehicles like trucks get these poor bridges lifespan shortened drastically. Trucks and busses could be rerouted on safe bridges and so on.

I generally am not afraid of bridges because they have convinced me that they're safe but if a bridge were to collapse under me and I'd make it out alive I'd probably have a bridge phobia.

Here's a tweet with a picture from December of 2018 of the bridge that collapsed today, showing a large steel beam rusted completely through.

So you could start with the lowest hanging fruit, the bridges that are in such bad condition that people post pictures of them on Twitter.

Here's the tweet you were referring to, I think: https://twitter.com/gpk320/status/1078885655634157569

How did people in that town pay for tearing down and replacing the bridge?

The problem Pittsburgh encounters is even demolition costs money. Can't squeeze blood from a stone.

The solutions are easier in a growing city than a declining one.

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