i live about a mile from the bridge, on century ave. i drive over that thing about 4 times a week! its so terrifying to see it so shattered now, when it looked perfect yesterday.
as for the construction workers with jackhammers potentially causing it, thats just not possible. bridges are supported by the trusses, not by the road over it. think of a very heavy piece of paper layed out over 2 pencils... jackhammers couldn't have caused this much damage.
but theres the interesting question- the bridge just went. it wasn't overloaded. in fact, a few of the lanes were closed due to the aforementioned construction work, and rush hour had already come and gone about an hour previous. it doesnt strike me as terrorism (theres no indication of this regardless), but what the hell causes a bridge to just "go" like that?