Clue to cause of bridge collapse

[godai]

Take a look at these before and after photos of the bridge. In the 'after' photo, near the right shoreline, there is a large steel framework which is intact. Compared to the 'before' photo, you can see that the entire framework has fallen backward, toward the shoreline. Sticking up in the air, on both sides of the bridge, are two green steel sections that were attached to other steel sections before the collapse. Seems that this may be a key area where the bridge failed. So much of the rest of the bridge is mangled but here there is this clean break in the structure. I think this also matches the video, as to where the bridge first fell.

http://www.washingtonpost.com/wp-srv/nation/interactives/minnbridge/index.html?hpid=topnews

[Liberal In Texas]

1. I think that "clean break" is an expansion joint. You can see it in the before pic

as the line that runs across the road. There is one that matches it on the other side as well. It would be logical that the roadway would separate cleanly at the expansion joints.