Sixty-Eight U.S. Bridges At Risk from Vessel Strike

The U.S. National Transportation Safety Board (NTSB) has recommended that 30 owners of 68 bridges across 19 states conduct a vulnerability assessment to determine the risk of bridge collapse from a vessel collision.

The recommendation comes as part of the ongoing investigation into the 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 (AASHTO).

Over the last year, the NTSB identified 68 bridges that were designed before the AASHTO guidance was established — like the Key Bridge — that do not have a current vulnerability assessment. The recommendations are issued to bridge owners to calculate the annual frequency of collapse for their bridges using AASHTO’s Method II calculation.

This does not mean that the 68 bridges are certain to collapse. The NTSB recommends that bridge owners develop and implement a comprehensive risk reduction plan if the calculations indicate a bridge has a risk level above the AASHTO threshold.

In 1991, AASHTO developed