Here's what surprised a structural engineering professor about the Baltimore bridge collapse
PHILADELPHIA -- The stunning collapse of the Francis Scott Key Bridge in Baltimore early Tuesday morning, after it was hit by a cargo ship, has many people wondering: could something similar happen to any of the major spans in other parts of the country?
For example, the Philadelphia region's Betsy Ross Bridge is similar to the Key Bridge. It was built around the same time and almost the same total length.
It's also the same type of bridge, known as a 'continuous truss bridge.'
However, there is one major difference between the Key Bridge and any of the bridges that span the Delaware River.
"All of our bridges have protection systems in place to prevent ships from striking them," said John Hanson, CEO of The Delaware River Port Authority.
RELATED: A list of major US bridge collapses caused by ships and barges
Hanson said the key difference sits in the Delaware River near the bridge support piers - structures called dolphins.
"When you talk about the Betsy Ross Bridge, we have concrete dolphins that are protected against ships, that will prevent a ship from striking the pier," said Hanson.
The circular structures could be seen from Drone 6.
When you look at video from Baltimore, you don't see them near the piers.
That's something a structural engineering professor at Drexel University in Philadelphia noticed right away.
"Why were there no protection systems around the pier?" asked Dr. Abieyuwa Aghayere.
Aghayere analyzes structural collapses. He was surprised that this type of bridge, known as a continuous truss bridge, completely failed.
"When something is continuous, it is supposed to at least hang on," he said. "What I saw was that once the pier that was supporting that span gave way, the bridge just went down. There was no hesitation."
That is something the NTSB will be looking at as the investigation into the collapse in Baltimore continues.
