It would cost at least $140 billion to repair all the nation's bridges if work began immediately, a nationwide safety organization said in a comprehensive report July 28.
The price tag will rise if the repairs are delayed, the group said.
"States simply cannot keep up with bridge maintenance," the report warns, adding that 73 percent of U.S. road traffic—and 90% of truck traffic—travels over state-owned bridges.
Nearly one in four bridges needs repairs, and the average age of America's bridges is 43 years—seven years shy of the maximum age for which most are designed, according to the report, titled "Bridging the Gap."
One in five U.S. bridges is more than 50 years old, the report says.
"Almost one in four bridges, while safe to travel, is either structurally deficient, in need of repair, or...too narrow for today's traffic volumes," the report from the American Association of State Highway and Transportation Officials said.
It was released days before the first anniversary of the collapse of the I-35W bridge in Minneapolis, which killed 13 people and injured 144.
The report identifies five main problems facing the nation's 590,000 bridges: age, congestion, soaring construction costs, lack of funds for maintenance and "the staggering costs of new bridges."
Rising oil prices have contributed to an increase of at least 50% in the price of steel, asphalt, concrete and earthwork over the past 2½ years, the report says, forcing repair delays.
"Thirty months of unprecedented construction inflation are forcing state officials to delay important bridge replacement projects," the report stated.
"Nearly every state faces funding shortages," it says, preventing them from doing work to "keep their bridges sound indefinitely."
The report says the country's bridges are safe, but it calls for investment, research and innovation, proper maintenance, public awareness and new financing options to keep them in good condition.
It identifies what it calls "a frustrating contradiction"—better engineering, materials and construction techniques are available, but "without a national commitment to bridge investment," states cannot afford the improvements.
