A report released by the National Traffic Safety Bureau (NTSB) on Tuesday revealed that if the Maryland Department of Transportation had conducted a risk assessment on the Francis Scott Key Bridge prior to its March 2024 collapse, officials would have discovered the heightened risk of catastrophic failure due to a vessel collision.
The bridge, which opened in 1977, was built under the 1969 edition of the American Association of State Highway and Transportation Officials (AASHTO) Standard Specifications for Highway Bridges. However, safety guidelines changed significantly after the 1980 Sunshine Skyway Bridge collapse in Tampa Bay. In 1991, AASHTO introduced a new Guide Specification for Vessel Collision Design, followed by a second version in 2009.
Federal Highway Administration (FHWA) regulations require that new bridges be designed to minimize collapse risks from vessel collisions. However, the NTSB report noted that “neither the FHWA nor AASHTO can require a bridge owner to complete a vulnerability assessment for a bridge designed before the release of the 1991 guidelines.” The Maryland Transportation Authority (MDTA) did not conduct such an assessment, though the NTSB recommended one.
Following the collapse caused by the Dali vessel’s impact, the NTSB conducted a vulnerability assessment using AASHTO’s updated Method II calculation. The analysis considered vessel speeds, waterway geometry, pier protection, and other environmental factors. The report determined that, if the MDTA had conducted this assessment before the collapse, it would have identified the bridge’s risk level as nearly 30 times greater than the AASHTO risk threshold for critical bridges.
The NTSB concluded, “Had the MDTA conducted a vulnerability assessment of the Francis Scott Key Bridge based on recent vessel traffic, as recommended by the 1991 and 2009 AASHTO Guide Specifications, the MDTA would have been aware that this critical bridge was above the threshold of risk for catastrophic collapse.”
The report also identified 72 bridges across 19 states that were “likely not designed and built to the AASHTO Guide Specifications.” Of those, 68 have not undergone vulnerability assessments. The NTSB urged the 30 owners of these bridges to conduct assessments to evaluate their risk levels and implement countermeasures.
NTSB Chair Jennifer Homendy told CBS News, “We conclude in our report that had the MDTA conducted a vulnerability assessment of the Key Bridge based on recent vessel traffic, the MDTA would have been able to proactively identify strategies to reduce the risk of a collapse and loss of lives associated with a vessel collision. We’ve been sounding the alarm since this tragedy.”
