> "
We would not let somebody use a new untested material in a bridge if it can not support the bridge just because "nobody knows how to make a bridge that works with the new material""
You might be interested to read about the Morandi Bridge collapse in Italy: https://www.engineering.com/story/italys-morandi-bridge-coll...
"When the Morandi Bridge was built, encasing a cable in concrete was innovative.", "the decision to pre-stress it was debatable", the concrete meant they couldn't check for cable rusting underneath, the concrete could have been supplied by the Mafia and under specification, "“We have used materials that are destined to deteriorate quickly, like those of the bridge in Genoa,” Bercich said in a post-collapse analysis".
"Settimo Martinello, director of bridge inspection company 4EMME Service, told CNN that there are “about 15 to 20 bridges collapsing every year” in Italy."
From another source: https://www.theguardian.com/cities/2019/feb/26/what-caused-t...
"In the 1960s little was known about the interaction of materials, or the effects of pollution and climate on corrosion.", "Morandi himself was surprised to see the structure age faster than he had anticipated. In 1979 he issued a report detailing a number of interventions to protect the structure against pollution from nearby factories"
It's not a collapse on its first day, but it undermines your suggestion that bridges are a solved problem, designed once with traditional methods, are well understood inside and out, and therefore never collapse.
Or if that's too old, how about the celebratory Millennium Bridge in London, a footbridge opened in June 2000 and closed two days later because it couldn't withstand the footsteps? https://en.wikipedia.org/wiki/Millennium_Bridge,_London#Open...