"I would not use the word crisis. Things are a little bit more urgent than they have been in the past. I would say there is concern," says some libertarian professor of the nation's 63,000 structurally compromised bridges. So the next time the span you're crossing seems a little creaky or in bad repair, don't worry too much about it. It's probably not going to collapse and send you hurtling to the treacherous waters below. Probably.