Key Bridge Collapse: NTSB Blames Lack of Vulnerability Assessment

During a recent news conference, NTSB Chair Jennifer Homendy warned 30 owners of 68 bridges across 19 states to conduct vulnerability assessments to mitigate the risk of a bridge collapsing due to a ship strike. The warning stems from the collapse of the Francis Scott Key Bridge in Baltimore, which the NTSB attributed to the lack of an assessment that may have prevented the incident.

NTSB says lack of 'vulnerability assessment'

On March 26, 2024, the 984-foot Singapore-flagged cargo vessel Dali, while moving out of Baltimore Harbor, experienced a loss of electrical power and propulsion, causing it to strike the southern pier supporting the central truss spans of the Francis Scott Key Bridge on the Patapsco River. The collision led to the collapse of the bridge, resulting in the deaths of six construction crew members and injuries to two others.

The NTSB Chair Jennifer Homendy revealed that the Key Bridge was almost 30 times above the "acceptable risk threshold" for critical or essential bridges, as per guidance from the American Association of State Highway and Transportation Officials (AASHTO). Despite the lack of certain collapse, the NTSB stressed that had the Maryland Transportation Authority (MDTA) conducted a vulnerability assessment on the Key Bridge based on recent vessel traffic, it would have been aware of the high risk and could have taken proactive measures to reduce the risk of collapse and potential loss of lives.

Homendy emphasized the urgency of taking action, stating, "Frankly, we've been sounding the alarm on this since the tragedy occurred. We need action. Public safety depends on it." In response to the incident, the NTSB has identified 68 bridges designed before AASHTO guidance was established, which do not have a current vulnerability assessment. The NTSB is recommending that the 30 bridge owners evaluate whether their bridges are above the AASHTO acceptable level of risk and, if so, develop and implement a comprehensive risk reduction plan.

Historical Context and Compliance

The vulnerability assessment calculation for new bridges on the National Highway System was developed and published by AASHTO in 1991 in response to the NTSB’s investigation of the Sunshine Skyway Bridge collapse in Florida. Furthermore, AASHTO reiterated its recommendation for existing bridges to undergo vulnerability assessments in 2009. Since 1994, the Federal Highway Administration (FHWA) has mandated that new bridges be designed to minimize the risk of catastrophic collapse from a vessel collision, taking into account the size, speed, and characteristics of vessels navigating the channel beneath the bridge.

The NTSB is advocating for the establishment of an "interdisciplinary team" composed of representatives from the FHWA, U.S. Coast Guard, and U.S. Army Corps of Engineers to provide guidance and assistance to bridge owners in evaluating and reducing the risk. According to the NTSB, reducing the risk may involve implementing infrastructure improvements or operational changes.