Water drops can diagnose bridge health

U.S. engineers say the sounds a highway bridge makes when rain falls on it can reveal hidden dangers of potential serious flaws in its structure. Researchers at Brigham Young University in Utah report the method, called impact-echo testing, can diagnose the health of a bridge's road deck based on the acoustic footprint produced by falling water. "There is a difference between water hitting intact structures and water hitting flawed structures," engineering Professor Brian Mazzeo said. "We can detect things you can't see with a visual inspection; things happening within the bridge itself." The BYU researchers are the first to use water droplets to produce acoustic responses; current testing relies on sounds made by solid objects such as hammers and chains used to strike the bridge. Such current methods can be time-consuming and require lane closures. "The infrastructure in the United States is aging, and there's a lot of work that needs to be done," researcher Spencer Guthrie said. "We need to be able to rapidly assess bridge decks so we can understand the extent of deterioration and apply the right treatment at the right time." The method is as simple as dropping droplets of water on the material and recording the sound, with the acoustic response indicating the health of the concrete. The new technique could help transform deck surveys into rapid, automated and cost efficient exercises, researchers said. "We would love to be able to drive over a bridge at 25 or 30 mph, spray it with water while we're driving and be able to detect all the structural flaws on the bridge," Mazzeo said. "We think there is a huge opportunity, but we need to keep improving on the physics."