How highway bridges sing -- or groan -- in the rain to reveal their health: Just a drop of water can indicate the stability of a bridge

A team of BYU engineers has found that by listening to how a highway bridge sings in the rain they can determine serious flaws in the structure.

Employing a method called impact-echo testing, professors Brian Mazzeo and Spencer Guthrie can diagnose the health of a bridge's deck based on the acoustic footprint produced by a little bit of water.

Specifically, the sound created when a droplet makes impact can reveal hidden dangers in the bridge.

"There is a difference between water hitting intact structures and water hitting flawed structures," Mazzeo said. "We can detect things you can't see with a visual inspection; things happening within the bridge itself."

The study presents a more efficient and cost-effective method to address the mounting safety concerns over bridge corrosion and aging across the U.S. and beyond.