USA: NTSB Recommends 68 U.S. Bridges Be Evaluated for Risk of Collapse from Vessel Strikes

Source: NTSB

WASHINGTON, March 20, 2025 – The National Transportation Safety Board (NTSB) is urging 30 bridge owners in 19 states to conduct vulnerability assessments of 68 bridges to determine their risk of collapse from vessel collisions. The recommendation stems from the ongoing investigation into the collapse of the Francis Scott Key Bridge in Baltimore.

The NTSB found that the Key Bridge, struck by the Dali container ship on March 26, 2024, had a risk level nearly 30 times higher than the acceptable threshold for critical or essential bridges, as defined by the American Association of State Highway and Transportation Officials (AASHTO).

The 68 bridges identified were all built before the AASHTO guidelines were introduced, like the Key Bridge, and currently lack a vulnerability assessment. The NTSB is asking bridge owners to calculate the annual frequency of collapse using AASHTO’s Method II.

This report does not claim the bridges are at immediate risk of collapse but urges proactive evaluation. If risk levels exceed AASHTO’s threshold, bridge owners should develop and implement a comprehensive risk reduction plan.

AASHTO introduced its vulnerability assessment calculation in 1991 following the Sunshine Skyway Bridge collapse in Florida. It reiterated the recommendation to states in 2009. Since 1994, the Federal Highway Administration (FHWA) has required all new bridges to be designed to resist vessel collision risks.

According to the NTSB, had the Maryland Transportation Authority (MDTA) conducted such an assessment, it would have known the Key Bridge posed an unacceptable risk and could have taken preventive action.

The NTSB also recommends the FHWA, U.S. Coast Guard, and U.S. Army Corps of Engineers form an interdisciplinary team to help bridge owners assess and reduce risk, whether through infrastructure upgrades or operational changes.

The Singapore-flagged Dali, measuring 984 feet, lost power and propulsion while departing Baltimore Harbor and struck the southern pier of the bridge. The resulting collapse killed six construction workers, injured one more, and left one crew member aboard injured.