The U.S. National Transportation Safety Board recommended March 20 that 30 owners of 68 bridges across 19 states conduct a vulnerability assessment to determine the risk of bridge collapse from a vessel collision, part of the ongoing investigation into the March 2024 collapse of the Francis Scott Key Bridge in Baltimore.

The NTSB found that the Key Bridge, which collapsed after being struck by the containership Dali on March 26, 2024, was almost 30 times above the acceptable risk threshold for critical or essential bridges, according to guidance established by the American Association of State Highway and Transportation Officials, or AASHTO.

In its investigation of the collapse, which killed six construction workers, the NTSB said the Maryland transportation authority failed to complete a recommended structural vulnerability assessment that would have shown the bridge was extremely prone to a collapse.

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Over the last year, the NTSB has identified 68 bridges that were designed before the AASHTO guidance was established — like the Key Bridge — and therefore do not have a current vulnerability assessment. 

“Today’s report does not suggest that the 68 bridges are certain to collapse,” a statement from the NTSB said. The NTSB is recommending that these 30 bridge owners evaluate whether the bridges are above the AASHTO acceptable level of risk, and in that case to develop and implement a comprehensive risk reduction plan.

According to The Guardian, the bridges recommended for assessment include the Brooklyn and George Washington Bridges in New York City, the Golden Gate Bridge in San Francisco, and the Sunshine Skyway Bridge in Tampa, Florida. All the bridges on the list are owned by their states’ transportation authorities.

Since 1994, the Federal Highway Administration, or FHWA, has required new bridges be designed to minimize the risk of a catastrophic bridge collapse from a vessel collision, given the size, speed and other characteristics of vessels navigating the channel under the bridge. 

The Marine Investigation Report is available online.