Natural Impact-Echo Bridge Structure Tests

Studying the sound of rain falling on bridges is a low-cost, practical and straightforward way of assessing structural integrity, according to US-based researchers.

Using a technique known as impact-echo testing, the Brigham Young University team has discovered a way to determine whether a bridge's construction is holding up, simply by listening to how raindrops sound when they strike it.

Those involved say, especially with the ageing state of US structures, their method is cheaper and more accurate than traditional visual inspections.

Impact-Echo Testing

Impact-echo testing isn't, itself, a new concept but, previously, engineers have used tools like chains and hammers to create sound. To do this has required bridge sections to be closed off to traffic and foot passengers and, overall, it's a lengthy and complicated process.

In contrast, the raindrop impact-echo testing harnesses nature to offer the construction industry potentially huge time and cost savings.

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

"The infrastructure in the US is ageing, and there's a lot of work that needs to be done", added his colleague Professor Spencer Guthrie. "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."

Bridge Structure Testing

Details of the two professors' novel bridge structure testing work appear in the current edition of the Non-Destructive Testing and Evaluation International publication.

Besides bridges, the professors suggest the raindrop impact-echo testing technique could have a number of other applications. These include aircraft structures, which are especially susceptible to corrosion.

"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 concluded. "We think there is a huge opportunity, but we need to keep improving on the physics."

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