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Visualizing the Baltimore Key Bridge collapse

In the early hours of Tuesday, a 984-foot container ship collided with a pillar of the Francis Scott Key Bridge in Baltimore, Maryland, causing the bridge to collapse. Six people are presumed dead.

Ship traffic through the Port of Baltimore — the 17th largest US port by total tonnage, or total weight of cargo entering and leaving the port, and fourth largest in the East Coast, according to 2021 data from the Bureau of Transportation — was suspended until further notice.

Hundreds of large cargo and tanker ships pass under the bridge as they travel to and from the Port of Baltimore each month, and they typically pass through the same narrow channel under the bridge, according to a CNN analysis of shipping data released by the Bureau of Ocean Energy Management and the National Oceanic and Atmospheric Administration.

The Dali appeared to be following the same pattern but clearly diverged moments before the collision with the bridge, causing the collapse, the records show.

The ninth largest US port for international cargo is blocked by the remains of the bridge. Ships are still able to move through the Port of Baltimore — which handled $80.8 billion worth of foreign cargo in 2023, according to the state government — but larger cargo items will have to wait until the bridge debris is cleared, Mark Conway, councilman for Baltimore’s 4th District, said on Wednesday.

When the Francis Scott Key Bridge was built in the 1970s, the largest ships were cellular container ships — the first vessels specifically built for handling containers. The Dali is a Neo-Panamax — a line of ships specifically designed to fit in the locks of the Panama Canal — and is nearly twice the length of the ships used when the bridge was built.

Bridges of the era when the Key Bridge was built weren’t designed to protect against collisions with ships as big as the Dali, according to a CNN investigation.

Traffic on the Key Bridge is heaviest during rush hour from 6 to 9 a.m. EST and 2 to 5 p.m., according to hourly traffic volume estimates from Inrix. The bridge collapsed around 1:30 a.m., when very few cars are using the road. Because the Dali sent a “mayday” signal before the impact, authorities were able to stop traffic, Maryland Gov. Wes Moore said, likely saving lives by preventing more vehicles from exposure to the collision.

While many of the 30,000 to 35,000 cars and trucks that used the Key Bridge daily can be rerouted through the tunnels, that will cause traffic delays.

The National Transportation Safety Board used the ship’s voyage data recorder, or VDR, to piece together a rough timeline of events leading up to the collision. The investigation into the cargo ship crash, however, could take up to two years, according to NTSB Chair Jennifer Homendy. She called the investigation “a massive undertaking” and said there are “many different components to the investigation.”

Here’s a minute-by-minute breakdown of when the Dali collided with the Key Bridge:

CNN’s Mark Thompson and Chris Isidore contributed to this report

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