Averting bridge disasters with new technology that could save hundreds of lives

University of Maryland News Desk: Millions of U.S. drivers cross faulty or obsolete bridges every day, highway statistics show, but it's too costly to fix all these spans or adequately monitor their safety, says a University of Maryland researcher who's developed a new, affordable early warning system. This wireless technology could avert the kind of bridge collapse that killed 13 and injured 145 along Minneapolis' I-35W on Aug. 1, 2007, he says - and do so at one-one-hundredth the cost of current wired systems.

"Potentially hundreds of lives could be saved," says University of Maryland electrical engineering researcher Mehdi Kalantari. "One of every four U.S. highway bridges has known structural problems or exceeded its intended life-span. Most only get inspected once every one or two years. That's a bad mix."

Kalantari has created tiny wireless sensors that monitor and transmit minute-by-minute data on a bridge's structural integrity. A central computer analyzes the data and instantly warns officials of possible trouble. He plans to scale-up manufacture in the fall.

More than one-in-four U.S. highway bridges are either structurally deficient or functionally obsolete, according to a 2009 estimate by the U.S. Society of Civil Engineers. Kalantari's sensors measure indicators of a bridge's structural health, such as strain, vibration, flexibility, and development of metal cracks. The sensors are small, wireless, rugged, and require practically no maintenance, he says.

...Newer "smart" bridges, including the I-35W replacement in Minneapolis, have embedded wired networks of sensors. But Kalantari says the cost is too high for use on older spans. "A wired network approach will cost at least 100 times more than a wireless alternative, and that's simply unaffordable given the strain on local, state, and federal budgets," Kalantari estimates....

...For almost a year, Kalantari has been testing his device in conjunction with the Maryland Department of Transportation, measuring the structural parameters of highway bridges in a real setting. This has enabled him to optimize the device's performance and energy consumption. His updated model is smaller and ten times more energy efficient than its predecessor....

Photo of the 2007 Minnesota bridge collapse from the University of Maryland website