Baltimore bridge disaster – Aston University expert explains why collapse was inevitable

The bridge in Baltimore snapped in several places and plunged into the river below.

Several vehicles fell into the chilly waters, and rescuers were initially searching for at least seven people.

Two people were pulled from the waters under the Francis Scott Key Bridge, one in serious condition, according to Baltimore Fire Chief James Wallace.

The vessel appears to have hit one of the supports of the Francis Scott Key Bridge, causing the roadway to break apart in several places and plunge into the water.

Dr Marina Bock, a lecturer in structural engineering at Birmingham's Aston University, said: "It i a metal truss bridge with a suspended deck, and from videos shown by the media it seems that the vessel has hit a main pier of the bridge.

"The main piers rest on soil underwater and they are part of the foundations of the bridge. This type of bridge is not designed to redistribute loads in the event of a main pier collapsing, there is a progressive collapse of the bridge. If the vessel had hit a small section of the suspended deck the bridge may have been able to survive the collision but not a main pier.

"I am assuming the first line of investigation will be to understand why the vessel could not avoid the pier when there were no other vessels around."

The ship caught fire and thick, black smoke billowed out of it.

Baltimore Mayor Brandon Scott said: “Never would you think that you would see, physically see, the Key Bridge tumble down like that.

“It looked like something out of an action movie,” Mr Scott said, calling it “an unthinkable tragedy”.

Fire chief Mr Wallace said authorities “may be looking for upwards of seven people” but said that number could change. It was not clear if the two rescued were included in the seven.

Sonar has indicated that there are vehicles in the water, where the temperature was about 47F (8C) in the early hours of Tuesday, according to a buoy that collects data for the National Oceanic and Atmospheric Administration.

Earlier, Kevin Cartwright, director of communications for the Baltimore Fire Department, said: “This is a dire emergency.”

He called the collapse a “developing mass casualty event”, though he didn’t know at the time how many people were affected.

He added that some cargo appeared to be dangling from the bridge.

Maryland Governor Wes Moore declared a state of emergency and said he was working to get federal resources deployed.

The FBI was also on the scene.

Agencies reported receiving emergency calls around 1.30am reporting a vessel travelling outbound from Baltimore that had struck a column on the bridge, causing it to collapse.

Several vehicles were on the bridge at the time, including one the size of a tractor-trailer truck.

The temperature in the river was around 47F (8C) in the early hours of Tuesday, according to the National Oceanic and Atmospheric Administration.

From a vantage point near the entrance to the bridge, jagged remnants of its steel frame were visible protruding from the water, with the on-ramp ending abruptly where the span once began.

Synergy Marine Group, which owns and manages the ship called the Dali, confirmed the vessel hit a pillar of the bridge at about 1:30am while it was in control of two pilots.

It said all crew members, including the pilots, were accounted for and there were no reports of any injuries.

Mayor Brandon M Scott and Baltimore County Executive Johnny Olszewski Jr posted that emergency personnel were responding and rescue efforts were underway.

The Maryland Transportation Authority said: “All lanes closed both directions for incident on I-695 Key Bridge. Traffic is being detoured.”

The bridge, which opened in 1977, spans the Patapsco River, a vital artery that along with the Port of Baltimore is a hub for shipping on the East Coast. It is named after the writer of The Star-Spangled Banner, the US national anthem.