It wasn’t a bird, and inspections didn’t use a crane. No, the flying object was a drone gathering data near bridges this summer.
The Minnesota Department of Transportation conducted studies at four structures using an unmanned aerial vehicle, or UAV. Operations took place in Little Falls over the Mississippi River and three other outstate sites.
Rick Braunig, manager of aviation safety and enforcement in MnDOT’s aeronautics office, said the agency considered sites in the Twin Cities, but safety concerns pushed the study to rural areas.
Completing field demonstrations of unmanned technology was the project’s goal, and according to the agency, the endeavor ending in June was successful.
“UAVs can be used for bridge inspection with little risk to inspectors and the public, and can reduce safety risks inspectors currently face,” a summary of the project stated. The tests showed drones can lower costs for equipment and traffic control, according to the summary. They can also reduce the need for snooper trucks, the vehicles with arms that extend to the side and below bridge decks.
A recent example shows potential dangers of those machines. In late August, a worker inspecting a bridge for the Connecticut Department of Transportation died after a snooper truck toppled over and crushed him between it and the road barrier.
According to Jennifer Zink of the MnDOT Bridge Office, the agency operates a fleet of six snooper trucks, which are stationed around the state. They cost about $750,000 each. Drones could reduce the wear and tear on that fleet, Zink said, and allow traffic lanes to stay open.
A multitude of benefits is emerging, but Zink said the rising technology doesn’t appear to be a complete replacement for the trucks or human workers.
Inspection of fracture-critical structures, maintenance and cleaning requires a hands-on approach, she said. But drones could supply initial looks and complete other less intensive operations such as peeking at supports and inspecting infrastructure that can collect debris.
As someone who has been stuck in a muddy culvert, Zink said the flying machines could provide some personal relief.
The summer study cost about $33,500. Chicago-based Collins Engineers, which also has a St. Paul office, was the contractor. Using its Federal Aviation Administration exemption to fly UAVs commercially, Colorado-based Unmanned Experts was the subcontractor on the project and operated an Aeyron SkyRanger drone.
Bev Farraher, director of the Bridge Office, said she had been intrigued by drones for some time. A sort of epiphany took place when she first observed a helicopter-type drone. After discussing possibilities with Zink and a consultant earlier this year, they decided to pursue funding, as the agency did not own a drone and wanted to work with a company that had the most technologically applicable machine.
The deadline on the use of money MnDOT secured was June 30. Unmanned Experts had federal approval for the use of its SkyRanger drone. Obtaining an OK for the use of a different UAV — under current FAA rules — takes time, Zink said. So the subcontractor and state agency were stuck with the one model.
Zink said a major goal for the second phase of MnDOT’s drone study, starting this fall, will be to use a machine that better applies to bridge work. She said they plan to use an eXom by SenseFly, a Swiss company with dealers in Minnesota.
Two downfalls of the SkyRanger, Zink said, were not being able to aim its camera at an upward angle and the machine’s tendency to lose its GPS signal when flying under a structure. The latter sent the drone into autopilot, return-to-home mode, she said.
She said at the beginning of November, the agency intends to use a UAV during a regularly scheduled inspection of the John A. Blatnik Bridge in Duluth. State workers will be testing to see if a drone can save time and money and increase safety. Potential benefits are not having any lane closures from snooper trucks or maintenance crews next to traffic, Zink said.
The Blatnik project, along with the potential for drones to help investigate the Duluth lift bridge before it receives a new paint job, would be far more public than the operations this summer. Farraher said the relative secrecy MnDOT employed with its initial tests were to keep the research in a more conducive environment.
“We did not know this would be a viable technology,” she said of the drone. “And research sometimes has failures. Sometimes folks don’t understand there are sometimes failures.”
The agency was attempting to respect the breadth of opinion on drones that exists in the state, Farraher said, even though workers weren’t using drones in ways that would be of great concern to the public. Her office simply didn’t want any possible negative perceptions hamstringing the pioneering project.
“This is one of the first state (Department of Transportation) studies of its kind,” said Barritt Lovelace of Collins Engineers in the project summary. Zink said Wisconsin counterparts have inquired about the project.
Braunig said the bridge study was the first experience with drones inside MnDOT’s aeronautics office. He said the technology has potential outside bridge inspections. In fact, state workers used one on the Iron Range this summer as part of the U.S. Highway 53 relocation project.
A newsletter update from August said a drone surveyed pit walls June 26 and 27.
“The information collected will be combined with drilling data to create a (3-D) model of the rock fractures,” said Pat Huston, project manager.
Drone technology is changing operations for MnDOT and other organizations, but Braunig cautioned people about putting too much trust in the machines.
“I don’t think people realize the damage that can be done,” he said, suggesting people visit www.knowbeforeyoufly.org, a website from the FAA and UAV industry groups. MnDOT also created an informational Web page in the last few weeks, Braunig said.