A malfunctioning signal wire has been identified as the cause of the blackout that led to the cargo ship Dali’s collision with Baltimore’s Francis Scott Key Bridge, according to a report released by the National Transportation Safety Board (NTSB) on Tuesday. The report also criticized the Maryland Transportation Authority (MDTA) for not adequately evaluating the bridge’s resilience to ship collisions.

The catastrophic incident occurred in the early hours of March 26, 2024, when the container ship Dali experienced a power failure and subsequently crashed into a support pier of the bridge. This impact caused sections of the bridge to collapse into the Patapsco River.

The NTSB’s comprehensive report revealed that an incorrectly installed wire resulted in a complete power outage, rendering the Dali unable to maneuver just moments before the impact. The board emphasized that the disaster might have been averted if Maryland had adhered to earlier issued safety recommendations.

“The National Transportation Safety Board finds that the likely cause of the Dali’s collision with the Francis Scott Key Bridge was a power loss due to a loose connection of a signal wire to a terminal block, stemming from the improper application of wireless label banding,” stated the board.

Despite the crew’s rapid response to the power failure, investigators noted that they had insufficient time to restore power before the ship collided with the bridge. The vessel’s close proximity to the bridge, coupled with delays in rebooting its systems, rendered the collision inevitable.

The report also faulted the MDTA for not conducting a vulnerability assessment, a step recommended by the American Association of State Highway and Transportation Officials to identify ways to protect bridges from ship strikes.

The NTSB said contributing to the collapse “was the lack of countermeasures to reduce the bridge’s vulnerability to collapse due to impact by oceangoing vessels, which could have been implemented if a vulnerability assessment had been conducted.”

Engineers testified that the Dali’s crew misused a flushing pump as a service pump, a practice the ship’s operator, Synergy Marine Group, failed to detect or stop. That misuse limited the vessel’s ability to recover power after the blackout.

The NTSB also criticized Synergy for allowing critical electrical systems to run in manual mode rather than automatic, which hindered the Dali’s recovery after the power failure.

“Staff found that Synergy operational oversight was inadequate because it did not discontinue crew’s ongoing use of the flushing pump as a service pump for the diesel generators aboard the Dali, and at least one other vessel,” NTSB engineer Bart Barnum said.

The board also found that communication failures prevented timely warnings to highway workers, who had no chance to evacuate before the bridge collapsed.

The NTSB’s findings came a day after Maryland officials said rebuilding the Francis Scott Key Bridge will take two years longer than expected and cost more than twice the original estimate. State engineers now say the project won’t be finished until 2030 and could cost as much as $5.2 billion — up from the initial $1.9 billion projection used to secure federal funding.

Jim Harkness, the MDTA’s chief engineer, told The Washington Post that inflation and market factors are driving the increase.

“Estimating is difficult on these larger projects,” he said. “The market factors, that all comes into play.” Transportation Secretary Sean Duffy had predicted in August that the final bill would be “double plus” the initial estimate once federal dollars were committed.

The NTSB’s findings paint a picture of cascading failures — from a single faulty wire to years of missed safety precautions — that combined to cause one of the deadliest infrastructure disasters in Maryland’s history.

As the state works to rebuild the bridge, the growing costs and timeline delays underscore how deeply the collapse continues to ripple through Maryland’s economy and infrastructure.