Closed Sherman Minton bridge is example of structurally deficient U.S. bridges.

A new report shows more than 18,000 of the nation’s busiest bridges, clustered in the nation’s metropolitan areas, are rated as “structurally deficient,” according to Transportation for America.

“The Fix We’re In For: The State of Our Nation’s Busiest Bridges” ranks 102 metro areas in three population categories based on the percentage of deficient bridges.

The report found Pittsburgh had the highest percentage of deficient bridges (30.4 percent) for a metro area with a population of more than 2 million (and overall).

Oklahoma City (19.8 percent) topped the chart for metro areas between 1-2 million, as did Tulsa, Okla. (27.5 percent), for metro areas between 500,000-1 million.

At the other end of the spectrum, the metro areas that had the smallest percentage of deficient bridges are Orlando, Fla. (0.60 percent), for the largest metro areas, Las Vegas (0.20 percent) for midsized metro areas, and Fort Myers, Fla. (0.30 percent), for smaller metro areas.

“There are more deficient bridges in our metropolitan areas than there are McDonald’s restaurants in the entire country,” says James Corless, director of Transportation for America – 18,239 versus roughly 14,000 McDonald’s. “These metropolitan-area bridges are most costly and difficult to fix, but they also are the most urgent, because they carry such a large share of the nation’s people and goods.”

Nearly 70,000 bridges nationwide are rated “structurally deficient” and are in need of substantial repair or replacement, according to federal data. Metropolitan-area bridges carry 75 percent of the trips that are made on structurally deficient bridges, Corless says.