Based on my many years of performing engineering investigations, plus my near complete ignorance about bridges and concrete, I am willing to bet the mortgage that the cracks reported had absolutely nothing to do with the failure.
The only information that makes it to the public domain quickly after a disaster that is factually correct is “something bad happened.” Everything else is noise and fog.
This isn’t a cheap novel about heartless designer engineers and greedy contractors. Investigators actually want to know what went wrong so it won’t happen again, and they will keep pushing until they find out. Lawyers and insurance companies want to know so they know who to blame and what to require to cover future risks. Designers and builders want to know so they don’t have to try to sleep at night after this happens on one of their projects. And in the process a barrel full of red herrings will be tossed about. And future bridges will be safer.
What happened this week in Florida is horrific, and I can’t imagine the heartbreak of the victims’ families. But if the answer were obvious it wouldn’t have happened. So we’ll all have to wait for the people with both expertise and access to the design and construction details to wade through the data and figure it out. Frustrating, but there’s nothing else for most of us to do.