States should calculate how possible changes in bridge weight, capacity, or evolving bridge conditions will affect gusset plates as part of their work to ensure bridge safety, Mary Peters, Department of Transportation Secretary, said in a January 15 advisory to state transportation officials.
The advisory follows updates by the National Transportation Safety Board (NTSB) that indicated that stress on gusset plates, the metal pieces that hold individual girders together on some bridges, may have been a factor in last summer’s I-35W bridge collapse in Minneapolis MN.
The Secretary noted while the NTSB has not yet determined a definitive cause for the collapse, she directed the Federal Highway Administration to issue the technical advisory out of an abundance of caution to ensure that comparable possible design flaws do not exist on similar bridges.
She said that the advisory makes it clear that state highway officials should go beyond the current standard practice and include gusset plates when calculating load capacity on the nation’s 13,000 steel truss bridges.
In the days after the I-35W Bridge collapsed last August, Secretary Peters issued two technical advisories to states. The first called on officials to inspect all bridges of similar design to the Minneapolis structure and the second advised states to be mindful of putting added weight on bridges during maintenance and construction projects.