Oh my!! How terrible.

[wx247]

Quite a tragedy.

http://www.msnbc.msn.com/id/4986957/

[Rainband]

Very very sad!!

[coriolis]

Without diminishing the tragedy, I'll get into the engineering. That's very tall and narrow beam. It's strong in the vertical direction, but weak in the lateral direction. The little pegs on top get encased in the concrete deck to give it lateral support. Once that's done, it produces a lightweight, but strong structure. I heard on the news that the contractor placed it but did not install temporary bracing. Then it snowed and the contractor didn't come back the next day. An eyewitness said that he saw it "bowing and twisting" before it fell. Undoubtedly a mistake by the contractor.

[Lindaloo]

What a tragedy!!! When I am traveling in a construction zone on the interstate I always look for the "bowing" of those steel girders.



Thanks for telling us about the engineering part of that Ed.

[Guest]

Very tragic! I have never heard of the "bowing" or twisting of the girders, though, before. That is certainly a new one for me.

[wx247]

Without diminishing the tragedy, I'll get into the engineering. That's very tall and narrow beam. It's strong in the vertical direction, but weak in the lateral direction. The little pegs on top get encased in the concrete deck to give it lateral support. Once that's done, it produces a lightweight, but strong structure. I heard on the news that the contractor placed it but did not install temporary bracing. Then it snowed and the contractor didn't come back the next day. An eyewitness said that he saw it "bowing and twisting" before it fell. Undoubtedly a mistake by the contractor.

Thanks Ed for the technical perspective of this tragedy.

[Josephine96]

I heard about this.. Quite sad..

[Stephanie]

I guess it is fortunate that there was only one car affected. As you saw, the traffic was backed up for miles and alot of people were heading to the mountains. I know I've travelled under that bridge when I've gone to see my father and Anne and we went to the mountains.

[azskyman]

We had a bridge totally collapse while under construction in Phoenix here back about the year 2000...but no one was underneath at the time.

This is one of those strange times when you would have to believe that your time is up and it was meant to be. Even if they had been in a different lane they may have been ok!