The USA’s National Transportation Safety Board (NTSB) has recommended that 30 bridge owners assess 68 bridges for vulnerability to vessel strikes.

The announcement is a response to findings of the investigation into the collapse of the Francis Scott Key Bridge in Baltimore in March 2024, in which six construction workers died.

The NTSB’s report, Safeguarding Bridges from Vessel Strikes: Need for Vulnerability Assessment and Risk Reduction Strategies, is available online and includes a list of the 68 structures and owners. It includes the Golden Gate Bridge in California, Georgia’s Talmadge Bridge, and Louisiana’s Gramercy Bridge.

The NTSB found that the Key Bridge was almost 30 times above the acceptable risk threshold for essential bridges. This threshold is set by the American Association of State Highway and Transportation Officials (AASHTO). The 68 identified bridges were designed before this guidance was established.

NTSB has reiterated that these 68 bridges are not in danger of collapse. But it recommends that owners evaluate the level of risk using AASHTO’s Method II calculation and, if needed, develop an appropriate risk reduction plan.

It has also recommended the formation of an interdisciplinary team with members from FHWA, the US Coast Guard and the US Army Corps of Engineers to give guidance to bridge owners.

The investigation by NTSB found that had Maryland Transportation Authority made a vulnerability assessment on the Key Bridge based on recent vessel traffic, it would have known that the structure’s risk was above acceptable levels. It could have used this information to reduce the risk of collapse following a vessel collision.