Millions of Americans rely on bridges that some experts say are at risk of collapsing.
An Associated Press analysis of 607,380 bridges, based on the federal National Bridge Inventory, found that 65,605 were classified as "structurally deficient" and 20,808 as "fracture critical." Of those, 7,795 were both — a combination of red flags that experts say indicates significant disrepair and risk of collapse.
A bridge is deemed fracture critical when it doesn't have mutiple protections and is at risk of collapse if a single, vital component fails. A bridge is structurally deficient when it is in need of rehabilitation or replacement because at least one major component of the bridge has advanced deterioration or other problems that lead inspectors to deem its condition poor or worse.
The Skagit Bridge in Washington State, which collapsed earlier this year and reopened over the weekend, was listed as fracture critical. The I-35W bridge that collapsed in Minneapolis in 2007 had received a structurally deficient designation prior to collapsing.
While Federal Highway Administration officials said that any bridge that is open is safe enough to drive over, other experts say if nothing is done to repair these briges, another one will fail eventually.
"The physics of these bridges is that they all can fall, it's just a matter of time," said Barry LePatner, author of Too Big to Fall: America's Failing Infrastructure and the Way Forward. "It's like a house of cards. If one piece breaks it all goes down. Those are dangerous bridges by any engineer's standard."
All 50 states contain bridges that fall into both the fracture critical and structurally deficient categories, including heavily used and iconic bridges like New York's Brooklyn Bridge.
LePatner, who runs a website that maps bridge deficiencies, says many of these bridges are frequently closed or have weight restrictions in order to be operated safely.
According to LePatner and other experts, many of the bridges that are structurally deficient were built at the dawn of the Interstate Highway System, when fewer Americans had cars. The average age of U.S. bridges is 42 years old. They were never meant to carry the capacity they currently do on a daily basis.
But fixing these bridges poses a political and monetary challenge. It would cost $20.5 billion a year annually to eliminate the backlog of repairs on bridges by 2028, but only $12.8 billion was spent last year, according to an analysis of the Federal budget by the American Society of Civil Engineers.
But Barry LePatner believes if states concentrated more on fixing infrastructure instead of starting new projects, the deficiencies could be solved.
"The money is there, it's just not being prioritized," he said.
Peter Moskowitz contributed to this report, with wire services