The bridges we still have are maintained. Bridges fail all the time, but we only repair the ones we want to keep. Your link to wikipedia as proof that bridges do not fail is a case of the observer fallacy. The wikipedia article tells us of some bridges that failed, not all bridges that failed.

Gumby's point that the Victorian era bridges we still have were over-engineered is I think a good point. However we might like to say that they were well-engineered, but I bet that even they have been in a state of on-and-off if not constant repair.