1 in 9 U.S. bridges in need of repair

• Federal Highway Administration estimates repairs would cost %2476 billion
• Average age of the structurally deficient bridges is 65 years old
• One expert says%3A %27We%27ve never had a better bridge system%22

More than one in nine bridges in the USA — at least 66,405, or 11% of the total — are structurally deficient, according to a new report.

These are not rarely used, out-of-the way structures: Each day, Americans take 260 million trips over structurally deficient bridges, says the report from Transportation for America, a Washington, D.C.-based coalition that works to improve transportation.

The report comes less than a month after the May 23 collapse of a span of the Interstate 5 bridge over the Skagit River in Washington state. Part of the bridge collapsed when it was struck by a truck with an oversize load. That bridge, built in 1955, was not structurally deficient.

The structurally deficient bridges are 65 years old on average, and the Federal Highway Administration estimates that repairing them would cost $76 billion.

A structurally deficient bridge isn't necessarily one that's dangerous or about to collapse; rather, they are bridges that require significant maintenance, rehabilitation or replacement.

The repair bill will likely increase as many of the nation's most heavily traveled bridges, including those built as part of the interstate system, near the end of their expected life spans. "You're seeing the aging of the system," says David Goldberg, a co-author of the report. "It really does parallel the (aging of) the Baby Boomers in a startling way."

This is a problem that has worsened since Transportation for America's last report on bridges, in 2011: Fifteen states have seen an increase in their structurally deficient bridges. The report projects that in 10 years, one in four bridges will be 65 years old or older.

In the two-year federal transportation funding bill it passed last year, Congress eliminated a dedicated fund for bridge repair. "The upshot is that bridge repair now must compete with other transportation needs," the report says. Money previously targeted for bridge repair was rolled into a new National Highway Performance Program, which can be spent only on highways that are part of the National Highway System, which includes interstates and major state highways. Nearly 90% of structurally deficient bridges are not part of the National Highway System.

Transportation for America recommends that Congress raise new dedicated revenues for transportation programs including bridges; that 180,000 bridges be made eligible for the new funding program, and that repair of bridges and highways be made a national priority.

Not everyone is alarmed over the state of the nation's bridges. "From my perspective, we've never had a better bridge system than we have right now," says David Hartgen, senior fellow at the libertarian Reason Foundation who co-authored a February report on the condition of roads and bridges in the USA. "The overall system is getting better slowly and steadily over time" as states work to improve their roads and bridges.

Hartgen, emeritus professor of transportation studies at the University of North Carolina at Charlotte, says it's good that more responsibility for repairing bridges is shifted from the federal government to the states. "The states are closer to the problem," he says. "I'm not overly pessimistic about the funding picture. At the state level, there is more willingness to raise state taxes for bridges."