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How Did A Cargo Ship Send A Massive Bridge Tumbling Into The River? Experts Weigh In.

It will likely take weeks or months for federal investigators to sort out exactly what led to a container ship striking and collapsing the Francis Scott Key Bridge in Baltimore, Maryland, on Tuesday. But shipping industry experts, engineers and law enforcement have started to glean information from videos, photos and accounts of the disaster.

The accident appears to have resulted from a perfect storm of mechanical failures, dated bridge design, and unfortunate timing and location.

The Dali, a 948-foot, Singapore-flagged container ship, was navigating out of the Port of Baltimore when it experienced a power issue and “momentary loss of propulsion.” Apparent attempts to slow the vessel proved unsuccessful. At 1:28 a.m., the Dali plowed into one of the bridge’s two main piers, sending almost all of the 1.6-mile long structure plummeting into the Patapsco River.

Approximately 90 seconds before the collision, the Dali’s crew sent out a mayday call which allowed authorities to halt traffic onto the bridge. Maryland Gov. Wes Moore (D) said during a press conference Tuesday that the distress call and quick action of law enforcement undoubtedly saved lives. But eight construction workers were unable to escape the bridge before it crumbled. Two were rescued from the water and six others are presumed dead.

Contrary to myriad conspiracy theories circulating in right-wing circles, federal and local officials have stressed there is no evidence of foul play. Maritime experts have described the incident as a freak accident.

“Losing power while you’re approaching a bridge would be just about the worst case scenario,” Michael Kucharski, a former maritime investigator at the National Transportation Safety Board, told CBS News.

Video of the incident shows the ship’s lights go dark as it approaches the bridge. The vessel then steadily veers to its starboard side before making direct contact with one of the bridge’s southern support structures.

“Everything that could have went wrong did go wrong, and the place, unfortunately, was right by the bridge,” Kevin Calnan, a maritime transportation professor at California State University Maritime Academy, told The Independent. “As far as engine failures and situations like this, it is rare. And then it’s exceptionally more rare for this to be in a port area.”

When the failure occurred, the Dali was operating on its own. Two tugboats had helped guide the ship out of the dock, but did not escort it out of the harbor, The Baltimore Banner reported. Experts told the outlet it is unclear if escort tugboats would have been able to intervene and prevent the disaster.

After losing propulsion, the crew dropped the ship’s anchors in a desperate attempt to slow the vessel, the Maritime and Port Authority of Singapore said in a statement. Clay Diamond, the head of the American Pilots’ Association, a trade organization for maritime pilots, told The Associated Press that the ship’s captain also ordered that the rudder be turned hard to port to keep the ship from turning to the right.

Kyle McAvoy, a maritime safety expert with Robson Forensic and a retired Coast Guard captain, refrained from speculating about what led to the disaster, noting that the federal investigation would dig into any mechanical or operational failures. But he said propulsion failures do occur on giant cargo vessels.

“There are steps that professional mariners will take as a result of these things,” he said. “It’s a very complicated issue. Basically most ships of this size, they’re like moving cities on the water. You have all kinds of machinery that’s driving your propulsion systems, machinery driving your electrical systems. And you have to maintain a plant to do that.”

In the event of power or engine loss, McAvoy said there are operational steps that the crew takes to address the issue, including dropping anchors.

“How that all is wrapped up into this situation is what the investigative process will have to pick apart,” he said.

Large cargo vessels are often equipped with redundant systems, meaning there would have likely been multiple failures that caused the ship to lose control, two maritime experts told The Baltimore Banner. Captain Jeffrey Spillane, the dean of the School of Maritime Education and Training at State University of New York System Maritime, told the publication that the plume of black smoke seen billowing from the ship ahead of the collision indicates it experienced a catastrophic issue.

“That’s a huge, glaring problem that tells me there was a lot more going on,” Spillane said. “There should have been multiple redundancies going on to prevent that.”

Experts have also zeroed in on the vulnerability of the nearly 50-year-old Key Bridge. Unlike more modern bridges, the Key was not built to withstand vessel collisions, as Matt Dursh, a bridge engineer, pointed out in a series of posts to X, formerly Twitter. He noted that the Key was similar to the original Sunshine Skyway Bridge over Tampa Bay, Florida, which collapsed in 1980 after being struck by a freight ship.

One way to prevent such catastrophic events is to construct barriers, known as “dolphins,” that protect a bridge’s piers.

“This is a mass of rock, sand, and steel that serves to stop the vessel before it makes contact with the bridge,” Dursh wrote, adding that he expects the bridge replacement in Baltimore will feature this defensive infrastructure.

Tuesday’s disaster has already launched a debate about what should be done to better safeguard bridge infrastructure from similar accidents. Retrofitting existing bridges with concrete dolphin structures is costly: One such collision prevention system being built at the Delaware Memorial Bridge in Wilmington has a price tag of $93 million.

At a White House press conference Wednesday, Transportation Secretary Pete Buttigieg said the federal investigation is likely to help answer “whether any design feature now known would have made a difference in this case.”

“It’s difficult to overstate the impact of this collision,” he said. “It’s not just as big as a building, it’s really as big as a block. One hundred thousand tons all going into this pier all at once.”

The National Transportation Safety Board is leading the investigation into the Baltimore bridge collapse. At a press conference Tuesday, NTSB Chair Jennifer Homendy said that the probe will be “very broad” and include reviewing the ship’s data recorders, and collecting information about the vessel’s operations and safety history, the vessel owner’s company policies, bridge construction and protective structures, and more.

“The NTSB doesn’t speculate, we provide facts,” she said. “So there isn’t a lot we can share right now.”

Asked about the NTSB investigation on Wednesday, Buttigieg said, “Part of what’s being debated is whether any design feature now known would have made a difference in this case.”

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