One of two things happened. Aliens crashed their invisible ship into it, or... God sat on it and broke it.
I can tell you all for a fact, it needed to be replaced. 2 years ago they ran a news story about how Minnesota had a bunch of shitty bridges that needed to be replaced, and that one was one of the big ones.
don't forget the $1 TRILLION [or was it 2 or 3 TRILLION] that DOV ZAKHEIM absconded with when he was comptroller of the pentagram....announced the day before the offices at the pentagram that were auditing this were destroyed.