Photo: City of Fridley, MN
As a tool for city maintenance operations, unmanned aerial systems (UAS), or drones, have unexplored potential. The City of Fridley, Minnesota, integrated a drone into its public works department and has been exploring the possibilities, constraints, and operation requirements of this new technology.
Fridley’s drone
Fridley’s public works department bought its drone—a Mavic Pro 2 Zoom—in 2019 after hiring Nick Ousky, an engineering technician and licensed drone pilot.
The drone came pre-equipped with a waypoint navigation system that could be used to send it on autonomous mapping missions, and Ousky downloaded a free, open-source program called OpenDroneMap to process the photos, videos, and GPS data gathered during flights.
“This opened several possibilities for us to enhance and expand our public works operations,” says Jon Lennander, Fridley assistant city engineer.
The department’s biggest use for the drone thus far has been conducting topographic surveys of current or future construction sites. Drone surveys can generate 2D or 3D maps that serve as a jumping-off point for preliminary design, and they can also collect quick information on more temporary construction features.
“We think that this is pretty viable for stockpiles for measuring quantities,” Ousky says.
Though less accurate than a ground survey, drone surveys are generally faster and collect more information, Lennander says, which increases the precision of stockpile volume calculation.
Drone pilot requirements
Operating a drone is a little more complicated than simply buying it and sending it out for a flight, Lennander says. The City of Fridley had to draft drone use policies for both the department and the city as a whole. In Minnesota, drones have to be registered with both the Minnesota Department of Transportation and the Federal Aviation Administration.
Drone operators also need a remote pilot certificate through the FAA, which ensures that pilots understand how to operate their drones in a safe and legal manner. Before a flight, Ousky said, a pilot’s responsibilities include:
- Preflight maintenance checks: Involves checking the drone itself and making sure the propellers, motor, batteries, etc., all work properly.
- Crew resource management: Involves assembling the transmitters, walkie-talkies, extra crew members, etc., necessary for the mission.
- Checking FAA airspace regulations: Generally, 400 feet is the highest a drone can be flown, and sometimes special authorization must obtained (near airports, for example).
- Checking weather: Depending on the drone’s ability to handle wind or cold, inclement weather can be a barrier to flights.
- Safety inspection of site: Involves checking the area for potential hazards and planning where to land the drone in an emergency.
During flight, pilots are also expected to have an understanding of any local, state, or federal laws that might apply to drones. Two of the biggest ones to watch out for, Ousky says, are ensuring that the drone is always within visual line of sight and ensuring that the drone never flies over people.
Looking to the future
Going forward, Fridley will likely continue to expand its use of the Mavic Pro 2 Zoom. Lennander surmises that it could potentially be used for site inspections (such as at erosion control sites), conducting traffic counts, capturing before-and-after imagery of infrastructure projects, or inspecting hard-to-reach structures (such as water towers or bridges).
The public works department might also consider getting more drones with different specifications, Lennander says. Smaller, less-invasive drones might be useful for residential areas, and bigger ones would be helpful for mapping greater distances.
“What these drones can do and will do is changing every day,” Lennander says. “We’ll continue to see what those changes are and whether they’re something we can do.”
Lennander and Ousky presented their findings in May as part of the Minnesota LTAP Demo Day Virtual Series. The event was sponsored by Minnesota LTAP, MnDOT, the Minnesota Local Road Research Board, and the Federal Highway Administration.
—Sophie Koch, MnLTAP freelancer
