> ... reinforced concrete cast in the 20th century hasn't held up as well as we wished ... How much of that problem is actual failures of the "standard practic

> ... reinforced concrete cast in the 20th century hasn't held up as well as we wished ... How much of that problem is actual failures of the "standard practice" technology at the time of construction, how much is expensive-to-replace old infrastructure reaching (or past) the end of its original design lifetime, and how much is "Surfside Syndrome" - dubious design + marginal construction + negligent-at-best maintenance + hard use? At least in my part of the country (SE Michigan), news coverage of crumbling old infrastructure fairly often includes bits about being well past its design lifetime. Or ongoing failures to do repairs, in the face of worse-and-worse inspection reports.