INDIANAPOLIS — Mark Bacon likes Indiana’s brand as the “Crossroads of America,” but in his rural community, there are some places where school buses, farm equipment and firetrucks can’t get across a creek.
Bacon is a corn farmer and county commissioner in Rush County, where nearly three-dozen bridges are closed or severely restricted with weight limits.
Another two-dozen are considered structurally deficient.
In Rush County, a long detour has become a way of life.
“It’s something we’ve learned to live with,” Bacon said.
Bacon and other local leaders around the state are looking for a better way. They hope a new method for testing a bridge's integrity will help them make smarter choices about spending scarce money on thousands of small spans throughout the state.
The method, developed by Iowa State University’s bridge engineering center, will be replicated by engineers at Purdue University this summer. They'll focus at first on a handful of county bridges, with more likely to follow.
Known as a weight-load test, the method involves attaching sensors to strategic points on a bridge. As increasingly heavy trucks cross, sensors detect when the bridge starts to shake or sway.
“It’s like a stress test on your heart,” said Pat Conner, research manager for Purdue’s local technical assistance program, which works with highway and road departments across the state.
The technology could replace the way bridges are now inspected — visually. County-hired engineers visit all bridges longer than 20 feet every two years to look for cracks or other indicators of stress.
Conner says sight inspections may miss hidden flaws. Or they may overstate a bridge’s problems and lead to unnecessary closures or restrictions.
After Purdue engineers tested rural bridges in rural Benton County last year, for example, weight restrictions were lifted.
Efforts to better evaluate bridges comes at a critical time. More than 1,500 of about 13,000 county-maintained bridges are closed or have weight restrictions. Bridges maintained by the state are generally not as old and in better shape.
For many of the old county bridges, original blueprints are lost to time, leaving inspectors to do more guesswork, Conner said.
“We’ve got a lot of rural bridges that are over 100 years old,” he said. “They were built at a time when there wasn’t much emphasis on maintaining those plans.”
Lawmakers set aside about $580 million over the next two years for repairs to local bridges and roads — about half of what is needed, according to infrastructure experts at Purdue. To tap into that fund, counties must submit their priorities for state approval.
The stress-test technology comes with a cost - up to $10,000 a bridge. But a coalition of agriculture groups - including the Indiana Soybean Alliance and Indiana Corn Marketing Council - are working with Purdue to reduce the price.
For those groups, better bridge inspections mean getting the most out of limited dollars for roads and bridges that farmers need to deliver commodities to grain elevators and processors.
For county officials like Bacon, the up-front cost of testing could save dollars in the long run.
“If we’ve got a better test that helps us know better what that bridge can stand, we’ll be a lot better off,” he said.