The Associated Press analyzed data involving 607,380 bridges in the National Bridge Inventory, which are subject to National Bridge Inspection Standards. On a national basis, there are 65,605 structurally deficient bridges and 20,808 fracture critical bridges, according to the most recently available federal government data.
A bridge is deemed "fracture critical" when it does not have redundant 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 span has advanced deterioration or other problems that lead inspectors to deem its condition "poor" or worse.
Some 7,795 bridges nationwide fall into both categories. Experts call that combination of red flags particularly problematic.
In Tennessee, 64 of the state's 19,721 bridges listed on the federal inventory are both fracture critical and structurally deficient. B.J. Doughty, spokeswoman for the state Transportation Department, said the department has current records on 57 of the bridges, which span the state from the Wolf River near Memphis in West Tennessee to Flat Fort Creek in the scenic Frozen Head State Park in East Tennessee.
Of those, she said:
— Six have been replaced with new structures.
— Three have been repaired.
— Sixteen are either under construction for replacement or repair.
There is considerable lag time between when state transportation officials report data to the Federal Highway Administration each year and when updates are made to the federal National Bridge Inventory. Because the federal inventory relies on information from the state departments of transportation, state officials have the latest records. And it's not clear how many bridges, if any, have been added to the dual categories of structurally deficient and fracture critical since the state last reported figures to the federal inventory.
Tennessee's many rivers and mountainous eastern terrain make the state's bridges vital connectors for smaller communities, metropolitan commuters and commerce.
Trucker James White travels the highways of Tennessee and Kentucky on a daily basis. He didn't name a specific bridge, but he said there are some smaller ones he hopes have been well inspected before he crosses them.
"There are some that I go across with a 90,000-pound load, and I'm thinking, 'If this bridge don't hold me, I'm gone,'" he said.
In 1989, a bridge collapse over the Hatchie River near Memphis killed eight people. A few years later, a bridge collapsed over the Tennessee River near Clifton.
Last year, Tennessee spent $84.6 million for bridge replacement. About 80 percent of that was federal money and roughly 20 percent came from state funds.
This year, $42.2 million — all state money — was spent on both repair and replacement.
Recent bridge collapses in Minneapolis and Washington state have made states more diligent about looking for problems, said Rick Daniels, vice president of a bridge fabricating company in Wisconsin who has over 40 years in the business. That's a vital first step, he said.
"States are a little bit more on their toes ... during their inspection processes in identifying the structures that really need to be replaced or rehabbed," he said.