68 bridges in 19 states potentially at risk: Is one near you?

Federal officials investigating the catastrophic collapse of the Francis Scott Key Bridge in Baltimore, Maryland, warned on Thursday that 68 bridges nationwide could be at similar risk.

The bridges that National Transportation Safety Board officials say potentially face similar risk of collapse include some of the most iconic and heavily-trafficked spans in the nation: the Golden Gate Bridge, the Chesapeake Bay Bridge and major New York City bridges.

The NTSB warning came during an update on its investigation into the Key bridge disaster. The Baltimore-area critical infrastructure collapsed into the Patapsco River nearly a year ago when Dali - a 984-foot container ship - lost power and struck bridge supports. Six construction workers died.

National Transportation Safety Board Chair ​​​​​​​​​​​​Jennifer L. Homendy warned that dozens of authorities nationwide haven’t assessed bridges to see what chance of catastrophe they face. 

“Frankly we’ve been sounding the alarm on this since the tragedy occurred,” Homendy said. “We need action. Public safety depends on it.”

NTSB investigators found that the Maryland Transit Authority had never done a risk assessment of the Key bridge. A federal postmortem found its risk of disaster was 30 times above established guidance.

Bridge authorities haven’t assessed 68 bridges across 19 states, Homendy warned.

What bridges are potentially at risk?

Bridges that could potentially face high levels of risk of collapse from collision span the entire country.

In New York, 13 bridges have not been assessed; eight in Louisiana; seven in California and Texas; six in Ohio; four in Massachusetts and Pennsylvania; three in Delaware and Maryland; two in Florida, New Jersey and Oregon; and one in Georgia, Illinois, Michigan, New Hampshire, Rhode Island, Washington and Wisconsin.

Among them are major New York City bridges including the Verrazano, Brooklyn, George Washington, Manhattan and Williamsburg. Also on the list are the Chicago Skyway, Mackinac Bridge in Michigan and Huey P. Long Bridge near New Orleans. 

A full list of the bridges is available in an NTSB report on the Key bridge collapse.

The NTSB said it will issue an urgent recommendation to bridge authorities to do an assessment.

Where did the assessment come from?

Among the bridges on the unassessed list is the same bridge whose collapse in 1980 spurred the development of the risk assessment standard — the Sunshine Skyway Bridge in Tampa, Florida.

A 1,200-foot span of the bridge collapsed after a 20,000-ton freighter struck a bridge support during a thunderstorm. 35 people died. It was rebuilt in 1982.

National transportation authorities responded by developing what Homendy called a “mathematical risk model” used to determine a bridge’s risk of collapse. 

Factors involved in the calculation, according to Homendy, include everything from data on the speed and traffic of vessels in the water to bridge and water channel geometry.

The American Association of State Highway and Transportation Officials published the risk assessment guidance in 1994.

Why haven’t they been assessed?

Bridges that haven’t been assessed share something in common — they’re old, dating as far back as 1883 in the case of the Brooklyn Bridge.

New bridges have to undergo assessments. Federal Highway Administration officials have required authorities to do so since 1994, according to the NTSB.

But many older bridges have not been held to the same standard though the NTSB has recommended multiple times that authorities perform assessments.

“When we issue urgent recommendations, we’re saying there’s an immediate risk,” Homendy said. “You need to take action.”

Michael Loria is a national reporter on the USA TODAY breaking news desk. Contact him at mloria@usatoday.com, @mchael_mchael or on Signal at (202) 290-4585.