Baltimore bridge collapse

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

The ship collision may have surpassed "the expected loads at the time of the bridge design," according to Northeastern professor Jerome Hajjar.

According to reports, a multi-agency emergency response involving state officials, emergency services, and the Coast Guard was sparked by the catastrophic collapse that sent automobiles tumbling into the lake.

Six persons remained missing on Tuesday afternoon despite the removal of two individuals from the water. They were all working as a construction team to patch potholes.


It is thought that no one was inside the cars when they plunged into the lake. The container ship had issued a mayday call, halting oncoming traffic towards the bridge.

According to Jerome Hajjar, the current president of the Structural Engineering Institute of the American Society of Civil Engineers and the CDM Smith Professor of Civil and Environmental Engineering at Northeastern University, the collapse emphasizes how earlier bridge designs may not have foreseen the risks posed by commercial shipping vessels becomingAccording to him, there may have been a "mismatch between the size of the load," or the power of the ship impact, and "the expected loads at the time of the bridge design," which led to the bridge collapse.

According to Hajjar, Northeastern Global News is seeing a genuine catastrophe.


A ship struck a bridge pillar in the video of the collapse, and the post subsequently seemed to give way and fall into the ocean.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.”
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 collapse, according to Jerome Hajjar, chair and professor at Northeastern CDM Smith, may have been caused by a "mismatch between the size of the load" resulting from the ship collision and "the expected loads at the time of the bridge design." Image courtesy of Northeastern University/Alyssa Stone

According to the American Society of Civil Engineers, the steel-arched Francis Scott Key Bridge, which is a portion of Interstate 695, was the second-longest continuous-truss bridge span in the world when it was constructed and is currently the third-longest. In 1977, it was finished.


The cargo ship, Dali, is flying the Singaporean flag. The owners of the 948-foot-long ship told the New York Times that it struck a bridge pillar around 1:30 in the morning and that nobody was injured.Hajjar said it’s hard to know if the bridge was structurally deficient. “It’s certainly possible that there was nothing deficient with the bridge — not when you take a force as large as a container ship and smash it into a support,” he says.

Hajjar says that commercial vessels, particularly in major ports, often navigate bridges of a similar length to the Francis Scott Key Bridge. 

Hajjar says he can’t speak to the specifics of the design of the Francis Scott Key Bridge, but adds: “I would assume that they design these supports to be able to withstand some amount of sideways or lateral load like this.”