It happens nearly a quarter-billion times a day in the USA: A car, truck or other vehicle is driven across one of the nation's 63,000 structurally compromised bridges.
That's from a new analysis by the industry group the American Road & Transportation Builders Association, which is warning that the situation might worsen.
In Georgia, 835, or six-percent, of the state's 14,768 bridges are classified as structurally deficient. This means one or more of the key bridge elements is considered to be in "poor" or worse condition. Most are city and county bridges, and the rest are state bridges. Every day, more than two million vehicles cross those bridges.
Twelve-percent of Georgia bridges are classified as functionally obsolete. This means the bridge does not meet design standards that are in line with current practices.
It would cost the state $14.8 billion to fix the bridges in the state.
The top most-traveled structurally deficient bridges in Georgia include several in Metro Atlanta:
- Cobb County's bridge over Clark Creek on I-75 at the Cobb-Cherokee line. The bridge was built in 1977. 105,710 vehicles cross the bridge every day.
- Cherokee County's bridge also over Clark Creek on I-75, 6.5 miles west of Woodstock. It was built in 1976 with the same number of daily crossings.
- Clayton County's bridge over Mud Creek on I-75 southbound to I-285 eastbound was built in 1959. Every day, 91,680 vehicles use it.
- There are two bridges in Coweta County on the list, both of them over the Transco gas lines. One on I-85 northbound, the other on I-85 southbound five miles northeast of Newnan.
State-by-state analysis: Check report on each state's bridges
The report comes against the backdrop of growing cries of alarm that the federal Highway Trust Fund, normally used to pay for roads and transit projects, could be insolvent by the fall unless Congress acts.
"Without congressional action, there will not be any federal support for any new road or bridge projects in any state in fiscal year 2015, which starts on Oct. 1," said Alison Black, chief economist for the road builders group.
Earlier this month, U.S. Sen. Patty Murray, a Democrat from Washington who chairs the Senate Appropriations subcommittee that handles transportation, warned her colleagues that the nation faces a "construction shutdown" later this year unless Congress acts. She called the potential problems with the Highway Trust Fund "another avoidable crisis," comparable to last fall's shutdown of the federal government.
Last week, the American Society of Civil Engineers urged Congress to take immediate action to avert insolvency in the trust fund. "We're at a critical crossroad," said president Randall Over.
The Highway Trust Fund is normally funded by revenue collected from the 18.4 cents-a-gallon federal gas tax. But the gas tax has not been increased since 1993, and soaring road-building costs have dwarfed receipts by as much as $20 billion a year in recent years.
Nearly one-tenth of the 607,380 bridges in the National Bridge Inventory, a database of information on bridges and tunnels, are rated as structurally deficient by the Federal Highway Administration; the average age of those bridges is 42 years. FHWA has estimated that the nation would need to spend about $20.5 billion a year to eliminate the backlog by 2028; the USA spends about $12.8 billion annually.
A structurally deficient bridge is not necessarily unsafe, according to the American Association of State Highway and Transportation Officials. When left open to traffic, these bridges typically require significant maintenance and repair to remain open, and eventually need to be rehabilitated or replaced to address deficiencies. To remain in service, these bridges are often posted with weight limits restricting the gross weight of vehicles permitted on the bridge.
The two-year, stop-gap funding bill passed by Congress in 2012 ends Sept. 30. Most infrastructure reform advocates are pushing for a 5- or 6-year funding bill of the sort that Congress has normally approved.
Options that have been discussed include raising the federal gas tax, implementing more tolling, supplementing gas tax revenue with money from closing corporate tax loopholes and transferring money from the General Fund.
David Hartgen, emeritus professor at the University of North Carolina-Charlotte and senior fellow at the libertarian Reason Foundation, says the nation has been making slow, but steady progress in reducing the backlog of deficient bridges.
"I would not use the word crisis," he said. "Things are a little bit more urgent than they have been in the past. I would say there is concern."
To put Georgia in perspective, while six-percent of its bridges are structurally deficient, the percentage is higher in 40 other states.