It just occurred to me that maybe the truck hit the bridge member because it was sagging. Maybe the bridge was ready to fail and the truck was the last straw.
It does seem that if a truck clips a bridge, the truck sustains a dent (see link) and the bridge collapses 25 feet into a river, that there is something wrong with the bridge.
But what's the story on the side of the truck? In the picture, the side of it seems to be missing. We seem to be looking into perfectly clean, white partitiions. What are we looking at there?