Maryland Transportation Authority Police quickly shut down traffic but failed to notify construction workers on the Francis Scott Key Bridge that a massive container ship without power was careening toward a bridge support, federal investigators said Tuesday.

A long-awaited meeting of the National Transportation Safety Board opened with maddening details about what investigators called a “preventable” accident that led to deaths and destruction.

Police, who were already present in the early hours of March 26, 2024, to conduct traffic control during active construction, successfully stopped vehicles from driving onto the bridge, preventing additional loss of life, investigators said.

But the construction workers were never notified. Had police made contact immediately upon learning of the wayward vessel, it would have given the crew a crucial 89 seconds to evacuate, investigators said.

The construction inspector, who was nearer to land, managed to jump to safety in time. Seven workers fell into the Patapsco River with the bridge. Six of them died.

An NTSB investigator testified that MDTA police had the mobile phone number of the inspector but did not call to warn of the emergency. Instead, one of the officers planned to drive to the worksite on the bridge once being relieved by another officer.

Nearly 20 months after the Francis Scott Key Bridge collapsed into the Patapsco River, federal officials are poised to make a final ruling about how it happened.

The NTSB, an independent federal agency, investigates most major U.S. transportation disasters, including the 2023 derailment of a freight train and resulting chemical spill in East Palestine, Ohio, and the February midair collision outside Reagan National Airport. It issues findings of probable cause and makes general safety recommendations aimed at preventing similar events.

The Key Bridge hearing is being livestreamed.

It began with a moment-by-moment account of the roughly 20 minutes between when the Dali left the Port of Baltimore and smashed into the bridge.

Investigators detailed mechanical failures that caused the ship to veer off course, the mitigating steps crew members took, as well as the calls to law enforcement to close the bridge to traffic.

Investigators ruled out factors like environmental conditions, fuel quality, possible ship crew impairment and the bridge’s physical condition.

Faulty wiring resulted in a “precarious electrical connection” within the ship’s power system that likely led to the first of two blackouts as the ship left port. Investigators found that infrared thermal imaging, a widely used technique in the shipping industry to inspect wire connections, was not in use on the Dali.

Tuesday’s hearing is not part of lawsuits filed in the wake of the collapse, including civil suits filed by the victims’ families against the companies that own and operate the ship. But the board’s findings could factor into how those lawsuits are resolved.

The Department of Justice last year accused the owner, Grace Ocean Private Ltd., and operator, Synergy Marine Group, of “jury-rigging” the Dali container ship that felled the bridge. In the civil case parties ultimately settled for $100 million. FBI agents boarded the ship as part of the federal investigation, and the DOJ could still bring a criminal case against the companies.

Findings from a preliminary NTSB report issued seven weeks after the collapse offered breadcrumbs pointing to issues the safety board would investigate further.

The Dali lost power twice while docked at the Port of Baltimore: The first was the result of human error, and the second came after a generator failed, according to that report.

It lost power two more times after departing, causing it to veer off course, skirt past the bridge’s small concrete “dolphins” designed to nudge wayward ships back into the shipping channel, and careen into a bridge pier.

The NTSB has been critical of the state of Maryland for not doing more to protect the bridge. In March, Homendy said that the Key Bridge was 30 times more susceptible to ship strikes than it should have been and that the Maryland Transportation Authority had not properly assessed its vulnerability based on highway guidelines issued in 1991.

Had the authority done the assessment, investigator Scott Parent said Tuesday, “the MDTA would have had information to proactively identify strategies to reduce the risk of a collapse and loss of lives associated with the vessel collision of the bridge.”

This story will be updated throughout the day