NTSB Sounds Alarm on Bridge Safety, Cites Lack of Assessment in Key Bridge Collapse
The National Transportation Safety Board (NTSB) has issued a stark warning to bridge owners across the United States, urging them to conduct vulnerability assessments on their structures to determine the risk of collapse due to ship strikes. This call to action comes in the wake of the tragic collapse of the Francis Scott Key Bridge in Baltimore, Maryland, which the NTSB suggests could have been prevented with a proper assessment.
During a press conference Thursday, NTSB Chair Jennifer Homendy emphasized the urgency of the situation, highlighting that the Key Bridge was nearly 30 times above the acceptable risk threshold for critical bridges, based on guidelines from the American Association of State Highway and Transportation Officials (AASHTO). The NTSB is specifically targeting 30 owners of 68 bridges across 19 states, all designed before current safety standards were established.
The collapse occurred on March 26, 2024, when the cargo vessel Dali, sailing under the Singapore flag, lost electrical power and propulsion while exiting Baltimore Harbor. The vessel collided with a southern pier supporting the central truss spans of the Key Bridge, causing its catastrophic failure. The incident resulted in the deaths of six construction crew members and injuries to two others.
Homendy stated that the Maryland Transportation Authority (MDTA) would have been aware that the Key Bridge exceeded acceptable risk levels and would have had the information to proactively reduce the bridge’s risk of collapse if they had done a vulnerability assessment. "Frankly, we’ve been sounding the alarm on this since the tragedy occurred," she said. "We need action. Public safety depends on it."
The NTSB has identified 68 bridges designed before AASHTO guidance was established that do not have a current vulnerability assessment. The agency recommends 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.
AASHTO developed and published the vulnerability assessment calculation for new bridges on the National Highway System in 1991 in response to the NTSB’s investigation of the Sunshine Skyway Bridge collapse in Florida. At the time, AASHTO also recommended that all bridge owners conduct a vulnerability assessment on existing bridges to evaluate their risk of catastrophic collapse in the event of a vessel collision. Decades later, in 2009, AASHTO reiterated that recommendation again.
Since 1994, the Federal Highway Administration (FHWA) has required new bridges be designed to minimize the risk of a catastrophic bridge collapse from a vessel collision, given the size, speed, and other characteristics of vessels navigating the channel under the bridge, according to the NTSB.
The NTSB is also recommending that the FHWA, U.S. Coast Guard, and U.S. Army Corps of Engineers establish an interdisciplinary team to provide guidance and assistance to bridge owners in evaluating and reducing the risk. Reducing the risk could mean infrastructure improvements or operational changes, according to the NTSB.
The vulnerability assessment process involves a detailed evaluation of a bridge’s structural integrity, the likelihood of a vessel collision, and the potential consequences of such an event. Factors considered include the bridge’s design, the depth and width of the waterway, the volume and type of vessel traffic, and the presence of protective measures such as bridge pier protection systems.
The absence of such assessments on older bridges raises serious concerns about the safety of these vital transportation arteries. Without a thorough understanding of the risks, bridge owners may be unaware of vulnerabilities that could lead to catastrophic failures. The Key Bridge collapse serves as a stark reminder of the potential consequences of neglecting these crucial assessments.
The NTSB will also be releasing more than 1,000 pages of investigative material on the public docket Thursday, including the bridge report and some interviews. This release of information is intended to provide greater transparency into the investigation and to share valuable lessons learned with the broader engineering and transportation communities.
Next week, the NTSB intends to release the hazardous materials, meteorological, and survival factors factual reports, as well as a study conducted by its office of engineering on vessel size increases and associated safety risk. These reports will provide further insights into the various factors that contributed to the Key Bridge collapse and the broader implications for bridge safety.
Voyage data recorder audio transcripts and associated data will follow, leading up to the NTSB releasing its final report, which will likely happen in the fall. The final report will include the NTSB’s findings, analysis, and recommendations for preventing similar incidents in the future.
The MDTA did not immediately respond to a request for comment. This lack of response underscores the need for greater accountability and transparency in addressing bridge safety concerns.
The NTSB’s urgent call for vulnerability assessments highlights the importance of proactive measures to ensure the safety of our nation’s bridges. By identifying and addressing potential vulnerabilities, bridge owners can significantly reduce the risk of catastrophic collapses and protect the lives of those who depend on these vital transportation links.
The Key Bridge tragedy serves as a wake-up call for the transportation industry and government agencies. It is imperative that bridge owners take immediate action to conduct vulnerability assessments and implement risk reduction plans. Failure to do so could result in further tragedies and erode public confidence in the safety of our infrastructure.
