I don’t think we really have most bridges built to last 100 years. What I see most is built to last 50 years and then usually it is stretched by patching/fixes

I don’t think we really have most bridges built to last 100 years. What I see most is built to last 50 years and then usually it is stretched by patching/fixes or ignoring the issues as those will be passed on to whoever is in charge politically when a bridge finally fails.