​On March 26, 2024, about 0129 local time, the 984-foot-long Singapore-flagged cargo vessel (containership) Dali was transiting out of Baltimore Harbor in Baltimore, Maryland, when it experienced losses of electrical power, propulsion, and steering and struck Pier 17, the southern pier that supported the central span of the Francis Scott Key Bridge (Key Bridge). 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.

A seven-person road maintenance crew and one inspector were on the bridge when the vessel struck it. Six of the highway workers died as a result of the bridge collapse. One highway worker survived the collapse with serious injuries, and the inspector escaped unharmed. One of the 23 persons aboard the Dali sustained a minor injury. Damage to the Dali exceeded $18 million. Cargo damages were undetermined. 

At the time of this report, replacement costs for the bridge were unavailable. Over 34,000 vehicles, 10% of which are trucks, that formerly traveled over the Key Bridge every day must now take alternate routes around and through the Port of Baltimore, increasing congestion and travel times. The Key Bridge was also the primary route for vehicles carrying hazardous materials. These vehicles, which are prohibited from using the tunnels under the Baltimore waterways, must now make extended detours around the port.

Read the NTSB's recommendation report: ​Safeguarding Bridges from Vessel Strikes: Need for Vulnerability Assessment and Risk Reduction Strategies

​We ​​determined that the probable cause of the contact of the containership Dali with the Francis Scott Key Bridge was a loss of electrical power (blackout), due to a loose signal wire connection to a terminal block stemming from the improper installation of wire-label banding, resulting in the vessel’s loss of propulsion and steering close to the bridge. 

Contributing to the crew’s inability to recover propulsion from the loss of electrical power was the limited time available due to the Dali’s proximity to the bridge. 

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 could have been implemented if a vulnerability assessment had been conducted by the Maryland Transportation Authority as recommended by the American Association of State Highway and Transportation Officials. 

Also contributing to the loss of life was the lack of effective and immediate communications to notify the highway workers to evacuate the bridge.              

​​​​As a part of this investigation, we issued 4 urgent new recommendations. Read the complete list of recomme​ndations​​​​.  ​​Read Safety Recommendations H-25-1 through -4​.