My wild a$$ theory.
There looked like there was a freight train that ran along the river and under the bridge at one point. The foundation that the piers stood on where constantly subject to vibration from the train and because these were not underwater they were not inspected as diligently.
The last train that was passing by cause the foundations to shake some more and finally let go.
Good theory. Doesn’t seem so wild to me. Sounds like maybe a variety of factors that all came together to cause this disastrous scene.
One thing I know, river traffic, freeway traffic, and economic activity in Minneapolis is really going to be altered.
What a mess.