In a statement, MDTA explained that preliminary estimates for the rebuild’s cost and timeline, made less than two weeks after the incident, were needed to request federal emergency relief funding for immediate clean up and recovery.

“Typically, a cost estimate would not be provided on a project of this size until much later in the design process,” added MDTA Executive Director Bruce Gartner.

Among the unknowns at the time, MDTA adds, were the size and cost of a pier protection system to safeguard a bridge that the agency says must be taller and wider than its predecessor to accommodate ever-larger vessels accessing the Port of Baltimore. The design, developed by Kiewit Infrastructure Co. under the $73-million first phase of a progressive design-build contract calls for a 1,665-ft-long main span supported by two 600-ft-tall main span pylons, with the bridge deck height above the main deep-draft shipping channel of at least 230 ft.

A generally more expensive construction environment also contributed to the revised rebuild estimate, MDTA says, citing a 72% increase in the Federal Highway Administration’s National Highway Construction Cost Index during the past five years. Along with leading to an uncertain construction and bonding market nationwide, MDTA notes that “the cost of raw materials and labor remains constantly in flux” as contractors price lingering inflation risks into their bids.

MDTA anticipates that negotiations with Kiewit on the project’s final design and construction cost will fall within the anticipated price range. Some aspects of the rebuild, including pile testing and demolition of the remaining original spans, are already underway.

While Congress endorsed then-President Joe Biden’s pledge for full federal funding of a replacement, subsequent friction between Maryland leaders and the Trump administration over the state’s disadvantaged business contracting practices has injected uncertainty into how much of that promise ultimately will be fulfilled.

In a statement, Gov. Wes Moore (D) said the state will “continue to work with the Trump administration to find ways to reduce costs and rebuild faster.” He added that the rebuild’s higher cost was the result of “federal design and resilience standards—not discretionary state choices.”

Along with promising to make “substantial financial commitments and contributions to support the Key Bridge rebuild, the state says any proceeds from pending litigation against the Dali’s owner and operator—Singapore-based Grace Ocean and Synergy Marine, respectively—will be used to pay for damages resulting from the incident, including reconstruction. Both companies have sought to limit their liability in the incident to less than $44 million, citing maritime law. 

Tracing the Collapse’s Probable Cause

NTSB’s exhaustive investigation of the chain of events that led to the Key Bridge’s collapse ultimately led to the maze of wiring making up the then-nine-year-old Dali’s power and control systems. Investigators determined that the probable cause was a loose signal wire connection to a terminal block—the result of where the wire’s label banding had been placed—resulting in the loss of propulsion and steering. Although crew members quickly restored the systems, the diesel generators soon failed again due to insufficient fuel pressure from a flushing pump that lacked the capability to reactivate following the initial failure.

NTSB investigators noted that the Dali crew members’ maintenance practices in the months prior to the incident included reliance on visual inspection and other techniques that were limited in scope when the systems were energized. More efficient fault identification technology such as infrared thermography imaging might have proven more effective had it been made available to the crew, the agency found. The wiring and pump issues figured in the federal government’s $102-million 2024 settlement with Grace Ocean and Synergy Marine to recover response and debris clean-up costs associated with the collapse.

According to the NTSB’s timeline, the second blackout caused the Dali to drift past two 28-ft-wide dolphins, eventually striking one of the Key Bridge’s main support pylons with a force nearly five times the structure’s lateral capacity, investigators say. The absence of adequate countermeasures to reduce the Key Bridge’s vulnerability to vessel impacts, which were not required when the structure was designed and built, was a contributing factor to the structure’s collapse and loss of life, the Board concluded.

The NTSB’s investigation also found that the eight-person Brawner Builders Inc., work crew performing concrete repairs on the main span was apparently unaware of the impending danger. As the unpowered Dali drifted toward the bridge, the Baltimore-based pilot radioed his dispatcher of the situation and urged the crossing’s immediate closure. MDTA police were then notified to close traffic at both ends, but word did not reach the crew’s inspector, who had provided his cellphone number to MDTA police in accordance with contract requirements.

Investigators estimate that had the crew been notified at the same time as MDTA police, they might have had approximately 90 seconds to drive to a safe location. Only the crew’s inspector and another worker survived the collapse. The Board noted that by calling MDTA police before notifying the U.S. Coast Guard—a departure from MDTA protocol for bridge threats—the dispatcher and officers were able to promptly halt traffic, potentially preventing further loss of life.

NTSB’s 17 safety recommendations resulting from the investigation include a call for the American Association of State Highway and Transportation Officials, the U.S. Coast Guard and U.S. Army Corps of Engineers and FHWA to help guide bridge owners to explore ways to reduce the risk of bridge collapse through errant vessel detection technology, design measures and incorporation of motorist warning systems capable of activating when a threat is identified and immediately halting traffic to the bridge. The Board also recommended that the American National Standards Institute update its A10.47 standard for roadway work zones to include an effective and immediate means of emergency communications to alert workers performing work on bridges over navigable waters.

In addition, the NTSB reiterated its March 2025 urgent recommendations for vulnerability assessments to be performed using AASHTO’s Method II calculation on nearly 70 bridges spanning key navigation channels. According to agency staff, evaluations have been completed on 35 bridges, with 22 found to exceed the acceptable risk threshold. Owners of those structures—among them, the Betsy Ross and Walt Whitman bridges in Pennsylvania and New Jersey, the Huey P. Long Bridge in Louisiana, and both spans of the MDTA-owned Chesapeake Bay Bridge—are currently working on risk reduction calculations. Vulnerability assessments of the remaining bridges cited by the agency are still underway.

NTSB will issue its final report on the Dali and Key Bridge collapse in the coming weeks.