NTSB confirms in final report that loose wire on ship led to Key Bridge collision and collapse

The National Transportation Safety Board (NTSB) released its final report more than 20 months after the deadly collapse of Baltimore's Francis Scott Key Bridge.

Investigators concluded that the blackout that left the Dali cargo ship powerless and on a collision course with the bridge was caused by a loose wire.

NTSB determined that a label was covering the base of its connector, which prevented it from being fully inserted. It was ultimately shaken loose, which cut off power and steering to the ship.

Six construction workers who were filling potholes on the bridge were killed in the collapse.

Maryland leaders say a new Key Bridge will cost around $5 billion, much more than initially estimated. The bridge likely won't be until at least late 2030.

NTSB hearing on cause of collision

Last month, NTSB hosted a public meeting to discuss what caused the collision and the collapse of the Key Bridge in March 2024. Several marine and engineering experts addressed the NTSB board in Washington, D.C.

The Maryland Transportation Authority (MDTA) said it reviewed the findings from the final report, and still maintained that the bridge collapse was the sole fault of the Dali. 

"The collapse of the Francis Scott Key Bridge and the tragic loss of life were the sole fault of the DALI and the gross negligence of its owners and operators," MDTA said in a statement in November. "The Key Bridge was approved and permitted by the federal government and complied with those permits."

The NTSB determined that a misplaced, thick, white label at the end of a small cable pushed it from having a secure connection, which caused the initial power failure and led to a cascading set of problems, ultimately causing the ship to slam into the Key Bridge. 

The investigation found that thermal scanners that may have detected the loose connection were not used as part of routine maintenance on Dali's many wires and cables, the investigation found.

"It just didn't fit, so it became disconnected. It backed out," NTSB Chair Jennifer Homendy said. "Sometimes it would hit the face of the spring clamp. There were significant Issues as a result of this, but the work that was done was pretty extensive. I like to say it's like a needle in a haystack. It is so hard to find, and having our team, which is very meticulous, to find these things, it took a really long time to do that. Finding something that was just slightly displaced is a lot of work."

Updated cost for Key Bridge rebuild

In November, the MDTA claimed the cost to rebuild the Key Bridge is going to be more than expected, and it's going to take longer, too.

MDTA estimates that the updated cost of the new Key Bridge is to be between $4.3 and $5.2 billion, with an anticipated open-to-traffic date in late 2030. 

Initially, officials had thought that the rebuild would cost around $2 billion and would be completed by the fall of 2028.