Minnesota bridge was weakened by a heavy load before it collapsed, report says
The piles of rock and sand, to be used in resurfacing the bridge, were placed over steel gusset plates, connectors joining bridge beams, that were thinner than they should have been, the National Transportation Safety Board said in an update on its investigation Monday.
The August 1 collapse near downtown Minneapolis killed 13 people and injured 145. The NTSB said it expects to produce its final report on the cause of the collapse by the end of the year.
The NTSB had previously cited the too-thin gusset plates and construction project weights as factors in the collapse, but Monday's update included drawings and tables that pinpointed the locations of those heavy loads on the structure.