You don't have to wait 100 years. You can build a bridge to alleviate traffic without any understanding that the bridge will in fact generate more traffic, and then you have to widen it a few years later (which also doesn't help). I know this has happened several times in NYC and I'm sure it has happened many other places where engineering know-how far outstrips knowledge of urban planning.

On the other hand having 10 times as many bridges could prove to be an impossibility when maintenance costs come knocking.

Well, invading a few fewer countries could pay for a few longer lasting bridges … it’s a matter of priorities.