The container ship that struck the Baltimore bridge is almost 1,000 feet long — here's why they keep getting bigger

• Experts say a major Baltimore bridge collapsed because the Dali container ship was so huge.
• Shipping vessels have grown from a capacity of 3,000 to 20,000 containers over the years.

Baltimore's Francis Scott Key Bridge collapsed on Tuesday morning after the container ship Dali collided with one of its supports.

Six construction workers are presumed dead. The city's fire chief said two people were rescued from the water, one of whom was in a "very serious condition."

Engineering experts previously told Business Insider that the bridge — built in the 1970s — stood no chance of withstanding the impact from such an enormous vessel.

"All bridge piers will be designed to resist impact from a vessel. And I think this will be unquestionably no exception to that," said Leroy Gardner, a professor of structural engineering at Imperial College London.

"I think it's the magnitude of the force in this case, which is extremely unusual, which has caused the problem for this bridge," he added.

The Dali container ship weighs about 95,000 tons and is 984 feet long — about the length of three football fields.

Container ships weren't always this big, so engineering codes at the time of the bridge's construction didn't account for such a potential impact.

Captain Rahul Khanna, global head of marine risk consulting at Allianz Global Corporate & Specialty, previously told BI how the vessels have grown over the years.

He said: "Decades ago, the ships with 3,000 TEU — that's the number of 20-foot containers that can fit on board — were considered the big ones."

The Dali has a capacity of 10,000 TEU. According to a report from the United Nations Conference on Trade and Development, the world's largest shipping vessels got 155% bigger between 2006 and 2020.

Some ships, like the Ever Given, which blocked the Suez Canal in 2021, can carry up to 20,000 20-foot containers.

Khanna said that in the future, container ships could grow to 50,000 TEU if there's such demand for advances in boat-building technology.

Concerns about enormous container ships arose in the wake of the Suez Canal blockage. Tuesday's incident could renew them — even if it doesn't have the same economic impact.

Ioannis Moutzouris, the Onassis senior lecturer in shipping finance and analytics at City, University of London, told BI that the effects of the Dali tragedy, "are not expected to be comparable to the Ever Given accident."