that bridge failed exactly where the crane was. is it possible the crane bumped the bridge?
According to this lengthy article, NTSB "investigators have confirmed that crews were tightening tensioning cables in a diagonal truss at the north end of the bridge on the day of the collapse."
The article says:
Adjusting tension cables, which ran like tendons through the 950-ton concrete span and the struts that connected a concrete canopy on the bridge to the walkway, can be a delicate operation. Over-tightening the cables, which are used to reinforce the concrete, can have devastating results, the experts say: It might cause torquing, or twisting, that would cause a specific cracking pattern in the concrete on impact with the road, something investigators would likely detect quickly.
If that's what they were doing, why was traffic allowed under the bridge?
I thought of that. It didn’t move at all. They had nothing hooked up yet. I didn’t know about any work being done in the area of the weakened area.