When completing a fracture-critical inspection on a 100-year-old bridge in Boone County, Mo., Shafer, Kline & Warren (SKW) recently partnered with the University of Missouri-Kansas City (UMKC) to collect inspection data more safely and efficiently by using a tethered drone system.
SKW and UMKC’s collaboration began in 2015 after a Missouri Society of Professional Engineers Western Chapter meeting in which Travis Fields, assistant professor of engineering, presented on his tethered drone prototype.
Through the SKW and UMKC partnership, UMKC was able to test its provisionally patented system in the field and receive feedback from bridge inspectors, while SKW was able to enhance its data collection and experience with drones.
“This system has the potential to really change how companies like SKW do inspection for bridges, as well as other structures, by reducing the dangerous situations for the personnel,” says Fields. “It is also more efficient, so that means less cost to the consumer, which generally comes back to the taxpayer; so that benefits everyone.”
Though last year’s prototype had image contrast issues and could not get close enough to the bridge structures to collect usable data, this year’s model was able to be used to view the floor beams and stringers on the bridge and determine whether there were structural issues that required further inspection.
“Today, with the creek being higher than normal, we normally would have had to hang underneath the bridge to view the floor beams and stringers – which is a safety issue,” explains Dustin Berry, SKW’s project engineer. “With the drone, we were able to get within arm’s reach and see everything we needed to see, and it saved me from hanging underneath the bridge.”
During the inspection, the camera on the drone streamed 4K video that SKW engineers saved for review. When viewing particular areas and critical connections, SKW directed Fields on which high-resolution images to capture. SKW included several of these images in the final bridge inspection report.
The tether, which connects the drone to a gas-powered generator, is lighter than the onboard battery and makes the flight time almost unlimited; it also eliminates the risk of a runaway, according to SKW.