Engineers warn major US bridges could collapse if hit by large vessels like one that downed the Francis Scott Key Bridge

Several major American bridges may collapse if hit by a large vessel, CNN reported on Wednesday, citing a group of structural engineers. The outlet examined “more than a dozen” key bridges in the wake of last week’s deadly incident in Maryland.

Most of the bridges examined by CNN appeared to be sufficiently protected with either “dolphins” or fenders – special structures designed to deflect or stop a ship before it could hit a critically important part of a bridge – or even artificial barrier islands, the broadcaster said.

Yet, citing federal data, CNN said that the majority of the bridges had “fracture critical members,” meaning that if one single element is knocked out, the entire structure could collapse.

At least three bridges lacked adequate protections, according to the broadcaster’s analysis. One of them is Chesapeake Bay Bridge near Annapolis. Built in 1952, with a second span added in 1973, the four-mile-long (6.4 km) structure is part of the cross-country US Route 50.

Some of the bridge’s concrete piers located near the main shipping channel might not withstand being hit by a vessel, CNN’s sources warned. Adel ElSafty, an engineering professor at the University of North Florida, told the outlet it was “lacking in safety measures” and could “very much be vulnerable to a ship impact.”

A vessel similar to the one that hit the Key Bridge “would eat through this in a second,” said Hussam Mahmoud, a Colorado State University engineering professor.

The Maryland Transportation Authority told CNN in a statement that it was looking at “options” to increase protection of the bridge. While the Chesapeake Bay Bridge is currently undergoing work to upgrade its road deck and parts of its steel superstructure, none of the current work involves fortifying it against ships, CNN said.

Apart from the Chesapeake Bay Bridge, the Crescent City Connection – a pair of cantilever bridges over the Mississippi River near New Orleans – were also singled out as particularly vulnerable. Opened in 1958 and 1988, over 250,000 vehicles cross them per day on average.

The state’s Department of Transportation described the bridges as “like triple protected,” but the experts approached by CNN disagreed. The fender system that the bridges have is “definitely inadequate,” Mahmoud said, calling the officials’ claims “nonsense.”