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 result of this investigation, we made the following new safety recommendations, including 4 urgent recommendations. Read Urgent Safety Recommendations
H-25-1 through -4.
To the Federal Highway Administration:
- In coordination with the US Coast Guard and US Army Corps of Engineers, establish an interdisciplinary team--including representatives from the Federal Highway Administration, US Coast Guard, and US Army Corps of Engineers--and provide guidance and assistance to bridge owners on evaluating and reducing the risk of a bridge collapse from a vessel collision. (Urgent H-25-1)
To the US Coast Guard and the the US Army Corps of Engineers:
- Support the Federal Highway Administration in establishing an interdisciplinary team--including representatives from the Federal Highway Administration, US Coast Guard, and US Army Corps of Engineers--and provide guidance and assistance to bridge owners on evaluating and reducing the risk of a bridge collapse from a vessel collision. (Urgent H-25-2)
To the Bay Area Toll Authority, the California Department of Transportation, the Golden Gate Bridge Highway and Transportation District, the US Army Corps of Engineers, the Florida Department of Transportation, the Georgia Department of Transportation, Skyway Concession Company LLC, the Louisiana Department of Transportation and Development, the New Orleans Public Belt Railroad, the Maryland Transportation Authority, the Massachusetts Department of Transportation, the Mackinac Bridge Authority, the New Hampshire Department of Transportation, the Delaware River Port Authority, the New Jersey Turnpike Authority, Metropolitan Transportation Authority Bridges and Tunnels, the New York City Department of Transportation, the New York State Bridge Authority, the Ogdensburg Bridge and Port Authority, the Port Authority of New York and New Jersey, the Seaway International Bridge Corporation, the Thousand Islands Bridge Authority, the Ohio Department of Transportation, the Oregon Department of Transportation, the Pennsylvania Turnpike Commission, the Rhode Island Turnpike and Bridge Authority, the Harris County Toll Road Authority, the Texas Department of Transportation, the Washington State Department of Transportation, and the Wisconsin Department of Transportation:
- Calculate the American Association of State Highway and Transportation Officials (AASHTO) Method II annual frequency of collapse for the bridge(s) identified in appendix B of this report for which you are responsible and inform the National Transportation Safety Board whether the probability of collapse is above the AASHTO threshold. (Urgent H-25-3)
- If the calculations that you performed in response to Safety Recommendation H-25-3 indicate that a bridge has an annual frequency of collapse greater than the American Association of State Highway and Transportation Officials threshold, develop and implement a comprehensive risk reduction plan that includes, at a minimum:
- guidance and assistance from the Federal Highway Administration, US Coast Guard, and US Army Corps of Engineers Interdisciplinary Team identified in Safety Recommendations H-25-1 and H-25-2, and
- short- and long-term strategies to reduce the probability of a potential bridge collapse from a vessel collision. (Urgent 25-4)
Summary of Bridge Owner Responses to Safety Recommendations H-25-3 and H-25-4
To the US Coast Guard:
- Conduct and publish the results of a study that examines the availability, feasibility, and safety benefits of redundant means to ensure that large single-propulsion-engine cargo vessels maintain propulsion and steering when maneuvering in restricted waters. (M-25-16)
- Propose to the International Maritime Organization that it revise the International Safety Management Code and associated guidelines to fully incorporate safety policy, safety risk management, safety assurance, and safety promotion into its safety management system requirements. (M-25-17)
- Notify the International Maritime Organization of the voyage data recorder technical issues encountered during our investigation into the contact of containership Dali with the Francis Scott Key Bridge and subsequent bridge collapse and submit to the International Maritime Organization a concrete proposal to require:
a. the recording of mandatory data inputs from systems that remain powered during a blackout,
b. the recording of engine room communications to the bridge,
c. the recording of multiple bridge microphone inputs such that the audio channels can be isolated or recorded independently, and
d. performance requirements for playback software that facilitates real world use, including enhanced criteria for exporting proprietary voyage data recorder data into open industry standard formats. (M-25-18)
To the Federal Highway Administration:
- Research hazard alert and sensing technologies capable of detecting errant vessels and bridge movements that would indicate a need for bridge closure, and would both warn and prevent motorists from entering a bridge once a threat is detected. Provide the results of your research to the American Association of State Highway and Transportation Officials. (H-25-28)
- Update your Guide Specifications and Commentary for Vessel Collision Design of Highway Bridges to include guidance in the selection of motorist warning systems. Evaluated changes should include Federal Highway Administration research on hazard alert and sensing technologies capable of detecting errant vessels and bridge movements that would indicate a need for bridge closure, and would both warn and prevent motorists from entering a bridge once a threat is detected. (H-25-29)
- Share with harbor safety committees nationwide the circumstances of the contact of the containership Dali with the Francis Scott Key Bridge and subsequent bridge collapse, highlighting the importance of having a procedure, including immediately available emergency contact information, for pilots to initiate contact with shoreside support in an emergency requiring shoreside action to ensure timely and efficient action by first responders and port stakeholders. (M-25-19)
- As part of your short-term bridge risk reduction and mitigation strategies to protect the traveling public, evaluate the need for and, if appropriate, incorporate motorist warning systems capable of activating when a threat is identified and immediately warn and stop motorists from entering onto the bridge. (H-25-30)
- Propose to the International Electrotechnical Commission Technical Committee 80 to revise IEC 61996-1 ed. 2 to require:
a. the recording of mandatory data inputs from systems that remain powered during a blackout,
b. the recording of engine room communications to the bridge,
c. the recording of multiple bridge microphone inputs such that the audio channels can be isolated or recorded independently, and
d. the updating of performance requirements for playback software that facilitates real world use, including enhanced criteria for exporting proprietary voyage data recorder data into open industry standard formats. (M-25-20)
To the American National Standards Institute Accredited Standards Committee on Safety in Construction and Demolitions Operations A10:
- Revise ANSI/ASSP A10.47, Work Zone Safety for Roadway Construction to include an effective and immediate means of emergency communications to alert workers performing roadway work on bridges over navigable waterways, which should consider the presence of law enforcement for traffic control. (H-25-31)
- Share the circumstances of the contact of the containership Dali with the Francis Scott Key Bridge and subsequent bridge collapse with the International Association of Classification Societies and urge them to distribute report MIR-25-40 to their members, highlighting:
a. the importance of avoiding placement of wire-label banding such that it impedes the proper insertion of a wire in a terminal block,
b. the benefits of using infrared thermal imaging as part of a preventative maintenance program for routine monitoring of electrical components to detect inadequate signal wire connections,
c. the potential risks that partially open radiator dampers can pose to emergency generators starting, and
d. the need for members to review their rules on acceptable emergency generator start design. (M-25-21)
To WAGO Corporation:
- Add a warning in your product data sheet accompanying WAGO terminal block 280-681 (model), as well as any other terminal block models or similar products that incorporate wire-label banding you manufacture, to explain that improperly placed wire-label banding can impede the proper insertion of a wire into a terminal block. (M-25-22)
- Incorporate proper wire-label banding installation methods into your electrical department’s standard operating procedures to ensure that wire-label banding installed on a wire does not impede the proper insertion of the wire into a terminal block. (M-25-23) Identify all active HD Hyundai Heavy Industries-constructed vessels with Hyundai-MAN B&W 9S90ME C9.2 engines installed, which are configured to Germanischer Lloyd rules and are designed to shut down on low cooling water pressure, and alert the current vessel owners of this configuration and the circumstances of this accident. (M-25-24)
- With classification society approval, implement into your preventative maintenance program and safety management system the use of infrared thermal imaging for routine monitoring of electrical components, including the means to detect inadequate signal wire connections. (M-25-25)
- Identify ships you operate that are equipped with a Hyundai-MAN B&W 9S90ME C9.2 engine and ensure that they are not configured to automatically shut down due to low cooling water pressure. (M-25-26)
- Develop, implement, and monitor for compliance and effectiveness a safety management system policy and procedure to ensure that vessel crews are using the fuel oil service pumps as designed for the diesel generator fuel supply systems installed on board your vessels. (M-25-27)
- Develop, implement, and monitor for compliance and effectiveness a safety management system policy and procedure to ensure that vessel crews are setting high-voltage breakers’ control mode to Automatic, unless the transformer breakers are being manually controlled for maintenance. (M-25-28)
- Identify ships you operate with similar arrangements to the Dali and notify crews of those vessels that partially open radiator dampers candelay or prevent the emergency diesel generator from starting automatically. (M-25-29)
Conduct and publish the results of a study that examines the availability, feasibility, and safety benefits of redundant means to ensure that large single-propulsion-engine cargo vessels maintain propulsion and steering when maneuvering in restricted waters. (M-25-16)
