I-35W bridge collapse update prompts new DOT advisory

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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, the Department of Transportation said in a new advisory sent to the nation’s state transportation officials Tuesday, Jan. 15.

The advisory follows Tuesday’s update by the National Transportation Safety Board indicating 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 Interstate 35W bridge collapse in Minneapolis.

Secretary of Transportation Mary Peters noted that while 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. “We want to take every possible step to address the latest update from the NTSB,” Peters said. “With a few calculations, we can help reassure travelers that our bridges remain safe.”

Peters said the technical 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.

“We are committed to ensuring the structural soundness of our nation’s bridges and will continue to support the NTSB in every way possible,” said Federal Highway Administrator J. Richard Capka.

In the days after the I-35W bridge collapsed last August, 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.