The NTSB reported that a single loose wire on the 984-foot containership Dali caused an electrical blackout, leading the vessel to lose propulsion and steering before striking Baltimore’s Francis Scott Key Bridge on March 26, 2024. The collapse of part of the 2.37-mile bridge killed six highway workers. Investigators found that wire-label banding prevented the wire from seating properly, triggering the blackout. The NTSB highlighted that the bridge lacked safeguards against large vessel impacts and issued new safety recommendations to bridge owners, the US Coast Guard, and multiple engineering and maritime organizations to prevent similar tragedies. The NTSB writes:
The NTSB said Tuesday that a single loose wire on the 984-foot-long containership Dali caused an electrical blackout that led to the giant vessel veering and contacting the nearby Francis Scott Key Bridge in Baltimore, which then collapsed, killing six highway workers.
At Tuesday’s public meeting at NTSB headquarters, investigators said the loose wire in the ship’s electrical system caused a breaker to unexpectedly open — beginning a sequence of events that led to two vessel blackouts and a loss of both propulsion and steering near the 2.37-mile-long Key Bridge on March 26, 2024. Investigators found that wire-label banding prevented the wire from being fully inserted into a terminal block spring-clamp gate, causing an inadequate connection. […]
”Our investigators routinely accomplish the impossible, and this investigation is no different,’ said NTSB Chairwoman Jennifer Homendy. “The Dali, at almost 1,000 feet, is as long as the Eiffel Tower is high, with miles of wiring and thousands of electrical connections. Finding this single wire was like hunting for a loose rivet on the Eiffel Tower.
“But like all of the accidents we investigate,this was preventable,” Homendy said. “Implementing NTSB recommendations in this investigation will prevent similar tragedies in the future.” […]
As part of the investigation, the NTSB in March released an initial report on the vulnerability of bridges nationwide to large vessel strikes. The report found that the Maryland Transportation Authority—and many other owners of bridges spanning navigable waterways used by ocean-going vessels—were likely unaware of the potential risk that a vessel collision could pose to their structures. This was despite longstanding guidance from the American Association of State Highway and Transportation Officials recommending that bridge owners perform these assessments.
The NTSB sent letters to 30 bridge owners identified in the report, urging them to evaluate their bridges and, if needed, develop plans to reduce risks. All recipients have since responded, and the status of each recommendation is available on the NTSB’s website.
As a result of the investigation, the NTSB issued new safety recommendations to the US Coast Guard; US Federal Highway Administration; the American Association of State Highway and Transportation Officials; the 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; and WAGO Corporation, the electrical component manufacturer; and multiple bridge owners across the nation.
