Only a government can afford to keep such resources idle "in case of emergency".
The current fad in government is that it's cheaper to replace a bridge than to keep painting it. The assertion is fluorescently untrue, of course, but it makes a nice sound bite, and it's true in the limited sense that the money comes out of a different pocket. ... and the bridges don't fall down right after you stop maintaining them, so the actual miscreants escape prosecution.
Similarly, right now nuclear engineers are pretty cheap because they've all just been ejected into the job market, so the politicians can say we'll wait to hire them until they're needed. .... at which time there won't be any, but again, that's not a current concern, so why plan for the future?
I will say that repainting a lead-paint bridge is a darn expensive proposition. It can often be replaced with a much simpler design which doesn't ever need painting (concrete, weathering steel.) Replacement typically means that most* of the lead paint stays in place on the steel and the entire painted member is used as feedstock for the steelmill.
Typically replacement is not just for that reason - you usually replace a bridge which is also too narrow and too low of a load limit for current vehicles. Most likely it will also have significant structural issues.
All that being said, we restore and preserve a heck of a lot of historic bridges in Texas.
*typically torch-cut locations are deleaded. The rest is left intact.
