Drones have become an affordable option for local agencies looking to save money, save time, and improve the safety, efficiency, and effectiveness of routine bridge inspections as well as a variety of other tasks.
According to FHWA bridge engineer Joe Campbell, good drone systems can now be purchased for $3,000 or less and operators certified in about a day of preparation, testing, and registration. Commercial drones used by many state DOTs often cost more than $40,000.
Campbell, who previously worked with Washington County and MnDOT, introduced public works staff from around Minnesota to affordable drone technology through his presentation and demonstration of drones and peripherals at the eighth annual Minnesota Roadway Maintenance Training and Demo Day, held May 16 at the Olmsted County Fairgrounds in Rochester.
Campbell said drones also have been used for inspecting other structures, pavements, and ditches. In addition, they’ve been used for public safety, response to a variety of emergencies including floods, project documentation, and cultural resource investigations. Users can also create “orthomosaics” of a series of GPS-tagged photos of sites or geographical features stitched together with specialized software.
“My choice is to walk around and take photos, or I put the drone up in the air,” Campbell said. “In a 10-minute flight, I’ve covered the whole site. I didn’t have any chances of getting injured or hurt. For my purposes, I’d much rather use the drone than do it the old-fashioned way.”
Drones typically come equipped with a range of options, depending on the model and price. Campbell cited the usefulness of features such as a high-definition camera with an optical zoom for photos and video, GPS, collision avoidance, and infrared vision. In addition, Campbell recommends buying a smart controller with a display (to avoid using a smartphone) and FPV (first-person view) goggles, which offer an immersive live display of the feed from the drone camera as well as review of previously captured photos and video clips.
FPV goggles make it easy to see small items in real-time, undiminished by sunlight. “This is a game changer,” Campbell said. “Goggles ensure that you take the images you wanted when you’re out in the field.”
In 2016, the Federal Aviation Administration introduced Part 107, a new classification for unmanned aerial systems (UAS), or drones, which changed the requirements for operators. Drone use for government or commercial purposes had been restricted to fully licensed airplane pilots, but now operators need only pass a knowledge test without ground school or flight time requirements. In addition, the new rules require that an operator must always keep the drone within sight, fly below 400 feet, and avoid flying directly above traffic or anyone not directly participating in operations. The State of Minnesota also requires drones to be registered.
The change in FAA rules, plus findings from a MnDOT study exploring the use of drones as a tool for bridge inspections, led Campbell to conclude that off-the-shelf drone products can meet the primary needs for routine bridge inspections. He shares the basic steps for starting a drone program through the FHWA’s Every Day Counts initiative, which encourages wide implementation of leading-edge technology throughout the transportation industry.
Demo Day attendees also received local road maintenance updates and training refreshers through a series of presentations provided by several other LTAP expert instructors.
—Michael McCarthy, LTAP editor
