THE US National Transportation Safety Board has found a single loose wire on the 9,962 TEU Dali caused the infamous collision with Baltimore’s Frances Key Bridge on 26 March 2024
At a public meeting at the Board’s Washington headquarters on Tuesday [18 November] 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.
The Maersk-chartered, Singapore-flagged vessel struck the 2.37-mile-long bridge, which partially collapsed with the loss of six highway workers. Investigators found that wire-label banding prevented the wire from being fully inserted into a terminal block spring-clamp gate, causing an inadequate connection.
After the initial blackout, the 300-metre Dali began swinging to starboard toward Pier 17 of the bridge; the pilots and the bridge team attempted to change the vessel’s trajectory, but the loss of propulsion so close to the bridge rendered their actions ineffective. A substantial portion of the bridge subsequently collapsed into the river, and portions of the pier, deck and truss spans collapsed onto the vessel’s bow and forwardmost container bays.
“Like all of the accidents we investigate, this was preventable,” chairwoman Jennifer Homendy said. “Implementing NTSB recommendations in this investigation will prevent similar tragedies in the future.”
Contributing to the collapse of the Key Bridge and the loss of life was the lack of countermeasures to reduce the bridge’s vulnerability to collapse due to impact by ocean-going vessels, which have only grown larger since the Key Bridge’s opening in 1977, the Board said.
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. 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.
As a result of the Dali 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; shipbuilder HD Hyundai Heavy Industries; shipmanager Synergy Marine Pte. Ltd; and WAGO Corporation, the electrical component manufacturer.