“Catastrophic bridge accidents are rare, but the number and severity of those due to ship collisions far exceed those due to winds, waves, and earthquakes combined.”  — Committee on Ship-Bridge Collisions (1983)

On Tuesday, March 26, 2024, shortly before 1:30 am, the cargo ship Dali drifted into the Francis Scott Key Bridge, causing the bridge’s collapse. The Port of Baltimore lost use of its main shipping channel down the Patapsco River into Chesapeake Bay, the city of Baltimore lost use of I-695, and most importantly, 6 construction workers fixing potholes on the bridge lost their lives.

While the bridge collapse was unexpected, it was not unanticipated. Since the bridge was first completed in 1977, engineers have noted that it could not withstand a collision by a large cargo ship against one of its main piers.

The incident investigation may take years to complete, but are there lessons for us to learn now?

What Happened?

Guided by tugboats, the Dali left the marine terminal at 12:39 am. About a half hour later, the tugboats withdrew, and the Dali was underway down the Fort McHenry Channel. Fifteen minutes later, at 1:24 am, the Dali lost power and propulsion. The harbor pilot – the local expert who is on board to take the ship out to the Atlantic – ordered the ship’s crew to restore power, which they are unable to do. He notices that the ship is starting to drift off course to the right and orders rudders to steer to the left as much as possible, given that the ship has no propulsion. A minute and a half after losing power, the pilot requested tugboat assistance, and then ordered the port anchor to be dropped. At 1:27 am, the pilot sent a mayday distress call.

Less than 30 seconds after the mayday call, the Maryland Transportation Authority (MTDA) sent units to close the bridge at both ends. At 1:28 am, the last moving vehicle cleared the bridge. A road crew on the bridge, consisting of eight people, was unaware of the emergency. Before police could warn them, the ship struck the bridge at 1:29 am. The bridge collapsed, taking down all three spans under the metal truss, and three other spans on the approach to Dundalk, Maryland.

Emergency responders rescued two members of the road crew from the river. Divers recovered the bodies of two others from the cab of their pickup. The four missing workers are presumed dead.

A Lot Went Right

The pilot followed emergency procedures as they had been planned: he ordered the power be restored, he ordered the rudders to steer to the left, he dropped the port anchor. In other words, he did everything from the ship that could be done and did it in a timely fashion. He didn’t prevent the collision with the bridge, but he slowed the ship and delayed the collision.

More importantly, the pilot didn’t try to handle the emergency without help. First, he requested tugboat assistance, which alerted harbor personnel that there was an emergency. Then the pilot sent a mayday call. His actions gave the authorities at MTDA time to act.

Not only did the pilot give MDTA time to act, they used it. They closed down the bridge and no one was killed or injured while travelling across the bridge. The crew of the ship survived as well. One crew member needed stitches, but otherwise, no one on the ship was killed or injured.

What Went Wrong?

It will probably take months or years for the various agencies to complete their incident investigations. It doesn’t help that there is a lot of liability to spread around, and the interested parties are going to have a stake in guiding the direction the investigation takes.

Some will want to blame sabotage or terrorism, although the FBI has ruled those out, because sabotage or terrorism are often easy ways to shift responsibility.

Some will blame the lack of sufficient fender systems or island barriers to protect the piers, something that has been required for new bridges since 1991, but the lack of a safeguard is never the primary cause of an incident. And some will focus on the failure of the diesel engines aboard the ship. Bad fuel? Poor maintenance? These will be questions for the NTSB to answer.

What Can We Learn Now?

We can think of this ship as a process that relies on propulsion to operate safely. It was NOT a deenergize-to-trip system. It needed propulsion, not only to move forward, but to steer. Without propulsion, the stacks of containers acted as sails, so even a slight breeze would move it off course. The only redundancy was the tugboats, and they were 15 minutes away when the power failed.

Worse, the diesel engines powered not only the propulsion system, but all of the systems on board the ship. The lights went out and the Voyage Data Recorder stopped recording any data from the ship systems except audio.

Do we have processes that rely on a single system to operate safely? Is the loss of a utility—electricity, steam, cooling water, compressed air—going to leave us adrift? Adrift, not dead in the water. If the Dali had been dead in the water, the collision wouldn’t have happened. The pilot, like an operator in a control room, used every tool at his disposal to control that drift, but he didn’t have the right tools. Have we provided our operators with the right tools to bring our processes to a safe state when an emergency happens?

Not a Near Miss

On the night the Dali drifted against the fourth pier of the Key Bridge, no one expected anything to go wrong. Even when the diesel power failed, the crew had every expectation that they would restore power and get back underway. The police who had shut down the bridge “out of an abundance of caution”, expected to reopen the bridge once the Dali passed by. Everyone expected, or hoped for, a near miss. Not a catastrophe. If it had been a near miss, we wouldn’t be talking about it now because it wouldn’t have been in the news.

But it wasn’t a near miss. It was a catastrophe. Let’s all this use this catastrophe to remind us, before we have our own catastrophes, to take another look at our processes to identify those systems which make us vulnerable.


  • Mike Schmidt

    With a career in the CPI that began in 1977 with Union Carbide, Mike was profoundly impacted by the 1984 tragedy in Bhopal and has been working on process safety ever since.