Sources close to the investigation told New Civil Engineer that when examining the main stay cables evidence of corrosion and damage had been found.
(warning: uncited facts are not welcome, nor is hearsay)
They suggested a failure of the cables – which were encased in concrete to protect them from the elements – may be behind the collapse.
https://www.newcivilengineer.com/latest/exclusive-collapsed-italy-bridge-investigators-find-corrosion-on-main-stay-cables/10034343.article
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however, in USA the famous silver bridge collapse ended in books being written about NOT covering potentially rusty components of critical sections
(covering rust with concrete would )
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HOWEVER - the bridge had problems with the deck being level when built and was corrected. some calculated the cables "had lengthened" and caused cracks in deck RECENTLY. the footing was in a muddy riverbed area.
it could also be the column moved and the design did not allow for it - so it broke, and the cable was simply the weakest link