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Eyes in the Sky: The beginning of the UAV Revolution

We are often encouraged, sometimes strongly, to do more with less. A nice sentiment but it’s rare when an opportunity actually presents itself when we can act on that advice. The Unmanned Arial Vehicle (UAV) does present that opportunity when it comes to civil engineering projects. As a tool, it could revolutionize our profession in terms of cost savings, time savings, and safety enhancement. When was the last we had a tool like that?

Currently, UAVs or drones are being equipped with multiple cameras and software to “look” at both bridges and construction sites. Jennifer Zink is a state bridge engineer for MnDOT and recently published an article in Roads and Bridges Magazine about UAVs and how her department is studying them for use in bridge inspections. She told us that a report about the first two phases of the study of UAVs will be available in about two months. She and her team already obtained funding from MnDOT to implement Phase Three of the UAV study.

Bridge Inspections

In this phase, MnDOT will take UAVs statewide to inspect bridges not only on state highways but also for bridges owned by cities and counties. These inspections will be free of charge to local agencies. Normally city and county engineers need to rent snoopers, operators, and crew from MnDOT to do these inspections, so this will be a huge for local officials.

Barritt Lovelace, is the regional manager for Collins Engineers, and his company has been supplying and flying the UAVs forMnDOT’s ongoing research. He worked on the first fly-by on the Bong Bridge in Duluth back in 2015 (https://youtu.be/a4QcwQZPwcU) and said that was pretty exciting because the weather in Duluth really tested the ability of the drone and the pilot. The wind off Lake Superior is legendary and, since it was one of the main bridges out of Duluth, there was a lot of traffic too. The test gave them a lot of confidence about being able to fly drones and do inspections safely, said Lovelace.

Collins just bought a new drone and it is outfitted with a high resolution still camera, a high definition video camera, an infrared camera, and ultrasonic detectors. The infrared camera can detect concrete delamination during inspections, and the ultrasonic detectors make sure the UAV doesn’t accidently clip a structure and damage itself.

Highway 53: a mile of rock

A recent project involving UAVs is at the Highway 53 bridge on the way to Ely, MN. This bridge stretches over a mine pit, and Andrew Shinnefield, an assistant engineering geologist, was in charge of making sure a cliff face near the construction site was safe and somewhat stable. He used the UAV services of Picture Factory in Minneapolis to do high-resolution photos and video of the whole cliff face. In this case, it was about a mile of rock he had to map, and the alternative to the drone was having a team of climbers on ropes climbing down and making measurements... every 50 feet. It would have taken months, says Shinnefield.

“We used photogrammetry to take high resolution photos, merged them together to then get the orientation of these joint faces of the rock,” said Shinne eld. This provided “a greater understanding of the rock as a whole,” he added.

The UAV’s scan of the rock face gave his team a lot more better data and mitigated a great deal of risk to both the climbers and to the project in the future. With this better data, Shinnefield could measure and analyze the high-risk rock faces on the project, but because of the time and money savings, he was also able to evaluate some of the medium-risk areas that he otherwise wouldn’t have had the time to look at.

What UAVs can and can’t do

Nobody has yet suggested that UAVs are going to replace traditional methods of inspections and analysis at construction sites and bridges. Snoopers will still be deployed, engineers will still be tapping on areas of bridges with hammers and people will still need to scale certain areas on ropes. What UAV can do, however, is quickly and cheaply scan an area so that inspections and analysis can be more ef cient, focusing on only the areas that need close-up human inspection.

The other thing UAVs can do, with the right software, is take the high-resolution images they capture and, using very advanced software, stitch the images together to create 3D renderings of bridges, rock faces, and more. These 3D models are incredibly valuable to engineers and Zink hopes to create a lot more of them during Phase Three. Right now, she said, we only have one for the St. Croix Crossing Bridge.

What does the future look like for UAVs? Zink is going to a UAV expo later this month to see the latest and greatest. She anticipates that eventually UAVs will be able to do crack detection and section loss on bridges. After that, who knows what kind of equipment could be mounted on a drone. That will be up to the imagination and ingenuity of those who operate them and those who employ them to get work done. 


by Bob Filipczak