Minnesota Tests Bridge Inspecting Drones

(Source: Grand Forks Herald)  

Flying a small drone around a bridge may be safer and less costly than traditional ways of inspection, with Minnesota officials planning more tests to gauge their usefulness.

After a summer drone test, next up will be a fall test that will include inspecting the state’s longest bridge, the 7,975-foot John A. Blatnik Bridge in Duluth. If that and other fall tests are successful, Minnesota could become the first state to use the unmanned aircraft to help inspect bridges.

“We are just looking at more innovative technologies to help us,” said Jennifer Zink, Minnesota Department of Transportation bridge inspection engineer.

Although no drone bridge inspectors are in use in the country, Zink said the technology could provide benefits: “Using drones could help MnDOT decrease the rising costs of bridge inspection while minimizing risks associated with current bridge inspection methods.”

Four bridges, of a variety of styles, were used in a summer test, in Chisago County, Orono, Little Falls and Stillwater.

It showed MnDOT officials that a drone could be considered when a hands-on inspection is not required and could be used when an area difficult to reach needs to be photographed. Drones can provide still, video and infrared photography.

Zink said advantages of drones include less need to block a lane of traffic while a truck with a long, articulated arm suspends a basket containing human inspectors under a bridge.

The fall test, to be conducted with a drone better equipped for inspection duty than the one used in July, will answer many of the remaining questions, Zink said, including how much money drones could save.

Drones are not being studied as a replacement for human inspectors, Zink said. Safety and costs are the main reasons, she said.

In some cases, she added, human inspectors might operate drones to extend their reach from their perch in a basket under a bridge. However, any time a drone shows a potential problem or its view is blocked, a human inspector would check out the area, she said.

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