Baltimore Bridge Collapse Linked to Single Loose Wire on Containership Dali, NTSB Determines

The National Transportation Safety Board (NTSB) announced Tuesday that a single loose wire within the electrical system of the containership Dali was the root cause of the vessel’s blackout and subsequent collision with Baltimore’s Francis Scott Key Bridge. This incident, which occurred on March 26, 2024, resulted in the catastrophic collapse of the bridge and the tragic deaths of six highway maintenance workers.

Investigators detailed at a public meeting that the inadequate connection of this loose wire, caused by wire-label banding preventing its full insertion into a terminal block, triggered an unexpected breaker opening. This event initiated a chain reaction, leading to two separate electrical blackouts onboard the Dali. These blackouts resulted in a critical loss of both propulsion and steering capabilities for the 984-foot-long vessel as it approached the 2.37-mile-long bridge. Despite efforts by the pilots and the bridge team to alter the ship’s course, the proximity of the bridge and the loss of essential control meant their actions were ultimately ineffective. The impact caused a significant portion of the bridge to fall into the Patapsco River, with debris also landing on the forward sections of the Dali.

The NTSB highlighted that the quick response of the Dali pilots, along with shoreside dispatchers and the Maryland Transportation Authority, in halting bridge traffic likely prevented an even greater loss of life. A road maintenance crew of seven individuals and one inspector were on the bridge at the time of the strike, and all six highway workers on site perished.

Further contributing to the severity of the collapse was the lack of robust countermeasures to protect the bridge from impacts by large ocean-going vessels. The NTSB noted that since the Francis Scott Key Bridge opened in 1977, the size of such vessels has increased dramatically. As an example, a previous incident in 1980 involving the much smaller containership Blue Nagoya striking the same bridge caused only minor damage. The Dali, however, is approximately ten times the size of the Blue Nagoya.

In a related investigation, the NTSB released a report in March examining the nationwide vulnerability of bridges to vessel strikes. This report indicated that the Maryland Transportation Authority, and many other owners of bridges spanning navigable waterways, may not have been fully aware of the potential risks associated with vessel collisions, despite existing guidance from the American Association of State Highway and Transportation Officials. Following this report, the NTSB issued letters to 30 bridge owners identified as potentially at risk, urging them to assess their structures and develop mitigation plans. All of these bridge owners have since responded, with updates available on the NTSB’s website.

As a direct result of this investigation, the NTSB has issued new safety recommendations to a range of entities, including the U.S. Coast Guard, the U.S. Federal Highway Administration, the American Association of State Highway and Transportation Officials, Nippon Kaiji Kyokai (ClassNK), the American National Standards Institute, the American National Standards Institute Accredited Standards Committee on Safety in Construction and Demolitions Operations A10, HD Hyundai Heavy Industries, Synergy Marine Pte. Ltd, WAGO Corporation (the electrical component manufacturer), and numerous bridge owners across the country. A full synopsis of the probable cause, findings, and recommendations can be found below, with the complete investigation report expected in the coming weeks.

Article by Ken Buckler, based upon information from the National Transportation Safety Board

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