> you don't have a reliable way to determine when the bridge is no longer safe I have a hard time believing this. Despite the ridiculous claims of another post

> you don't have a reliable way to determine when the bridge is no longer safe I have a hard time believing this. Despite the ridiculous claims of another poster in this thread (that rebar just spontaneously and completely turns into rust) properly formulated and surfaced concrete and steel don't just rot on the inside with no external signs of decay. If you have repeated water intrusion, you will see seeping and cracks. If you have increasing stress, you'll see spalling. You can core concrete, drill out and patch rebar if you have spot damage. In general I find the sentiments in this thread bizarre since the vast majority of long-lasting buildings now and in the past century are made of concrete (many of the more modern ones have a concrete foundation and wood or steel superstructure). You don't see many old wood structures because most of them decayed and were torn down - there's a reason why you don't see many wooden bridges standing. Concrete is the closest thing that we have structurally to something that can last forever, and we're learning more about how to make it last longer all the time. Let me know if you have links that discuss maintainability of concrete in this context. Would be glad to learn more.