Potential Causes of Baltimore Bridge Collapse from a Structural Engineering Perspective

CEE Professor Jerome Hajjar explains the potential causes of the catastrophic Baltimore bridge collapse in which several people died, and the risks posed by older bridges and large commercial shipping vessels.

This article originally appeared on Northeastern Global News. It was published by Tanner Stening. Main photo: A cargo ship is shown after running into and collapsing the Francis Scott Key Bridge on March 26, 2024 in Baltimore, Maryland. (Photo by Rob Carr/Getty Images)

How did ship collision cause Baltimore bridge collapse? Structural engineer discusses possible design factors at play

A major bridge in Baltimore collapsed Tuesday morning after it was struck by a container ship.

The catastrophic collapse sent cars plunging into the water, initiating a multi-agency emergency response involving state authorities, emergency personnel and the Coast Guard, reports say.

Two people were pulled from the water, but six people are presumed dead as of Wednesday. All were part of a construction crew filling potholes.

Nobody is believed to be in the vehicles that fell into the water. A mayday call by the container ship had stopped traffic approaching the bridge.

Jerome Hajjar, the CDM Smith Professor of Civil and Environmental Engineering at Northeastern University, and current president of the Structural Engineering Institute of the American Society of Civil Engineers, says the collapse highlights how older bridge designs may not have anticipated the risks posed by commercial shipping vessels becoming larger in size over the years.

He says the bridge failure could have been the result of a “mismatch between the size of the load,” or the force of the ship collision, and “the expected loads at the time of the bridge design.”

“This is a true tragedy,” Hajjar tells Northeastern Global News.

Video of the collapse showed a vessel colliding with a pillar of the bridge, which then appeared to give way and collapse into the water.

“The container ship must have significantly damaged the support structure, and a bridge of this span, if the support structure loses its or even displaces significantly, that could be enough to cause the bridge to fail,” Hajjar says. “And once that support structure goes, the distance to the next supports on either side are too far.”

Northeastern CDM Smith professor and chair Jerome Hajjar, says the collapse may be a result of a “mismatch between the size of the load” caused by the ship collision, and “the expected loads at the time of the bridge design.” Photo by Alyssa Stone/Northeastern University

Hajjar continues: “It’s possible that as the support failed, it was essentially pulling down the bridge as well. But even if the bridge had just been bearing on it, if that support structure starts to fail, and it permits the bridge to deflect down significantly — that’s enough to cause the failure.”

The steel-arched bridge, Francis Scott Key Bridge, a part of Interstate 695, was the second-longest continuous-truss bridge span in the world when built — and remains the third longest in the world, according to the American Society of Civil Engineers. It was completed in 1977.

Read full story at Northeastern Global News

Related Faculty: Jerome F. Hajjar

Related Departments:Civil & Environmental Engineering