Inspecting Oregon — Using Drones to Assess Bridges & Towers
Oregon State University (OSU) is one of the United States’ front runners in the field of infrastructure inspection using drones. Its UAS team is working on not only inspecting a wide range of the state’s bridges, but more recently added communications towers too, with the possibility of even moving onto indoor projects in future. Waypoint caught up with two of OSU’s key staff to discuss their research and findings so far.
Dan Gillins is Assistant Professor of Geomatics at OSU’s College of Engineering and actively uses UAS in his research. His colleague, Mark Peters, is the university’s Director of UAS Operations.
Hi Dan, Hi Mark. Do you want to start by giving us an overview of OSU’s current drone use?
Dan: Sure. We are currently using a senseFly albris quadcopter for inspecting bridges and wireless communication towers. This research is funded by the Oregon Department of Transportation. We also have a few other ongoing projects involving UAS.
The OSU’s UAS team, which includes Assistant Professor of Geomatics, Dan Gillins, above, is using its senseFly drone to inspect bridges and communication towers across the state.
Let’s delve into your bridge work first then. Could you tell us more about that?
Dan: We received two research grants last year from The Pacific Northwest Transportation Consortium (PacTrans) and from the Oregon Department of Transportation to study the use of unmanned aerial vehicles (UAVs) for inspecting bridges. This research then started last Fall, in 2015.
We started by using a DJI Phantom quadcopter and the work went pretty well. However, during the testing we realised that we wanted to get a more professional-grade system. We were in need of a system that was capable of flying safely underneath the bridge, had a front-mounted camera which could capture imagery both above and below the aircraft, and carried sensors for detecting obstacles since we needed to fly very close to structures in order to perform the inspection.
The main objective of the research was to help departments of transportation, or DOTs, to carry out one of their mandates, which is to inspect bridges every two years, as required by the Federal Highway Administration. This is a huge and very costly mandate that can require lots of different equipment: if bridges are big enough for example, a DOT may hire climbers to go out with ropes and harnesses. They might spend up to a week climbing around the structure, looking for defects such as loose bolts and cracks. For the most part, this work is done visually. Usually an inspector has to be right up against the bridge to see what they want to see.
Usually an inspector has to be right up against the bridge to see what they want to see
The Oregon DOT is very interested in using drones as a tool to minimise the amount of time an inspector needs to be on these structures—to improve safety and as preliminary assessment before a DOT does spend money to put inspectors on them.
Operating the albris drone in Interactive ScreenFly mode using its dedicated USB controller.
When you moved from your first consumer drone to the senseFly albris, why did you choose this particular drone to move ahead with? What stood out about it?
Dan: With the first drone, we got close to the bridge and we recorded some close-up HD video, which we shared with Pactrans and bridge inspectors. That was nice data, but we wanted to also get under the bridge. For that we needed a drone that had that capability.
With the first drone, we got close to the bridge and recorded some good HD video … but we wanted to also get under the bridge
With the albris, its camera is front mounted, so looking straight up is possible. And it has the ultrasonic sensors, which can be used instead of GPS to help the operator see and avoid obstacles. It also has a flash light built into its camera head, which may not sound like an important feature, but you really do need this extra light at times.
You mentioned inspectors previously climbing structures such as bridges. Would that typically be inspectors who have learned to climb, or climbers who have learned to inspect?
Dan: It’s a little bit of both. In some cases, it’s that an engineer learned to climb. But in many cases, it means hiring a climber who reports back to the engineer. A bit of a mixture then, depending upon the complexity of the bridge.
DOTs also often use snooper cranes, whereby the inspector will dangle underneath the deck in the bucket of the crane. That at least takes the climbing element away, but it’s expensive to mobilise those big cranes and still pretty dangerous work.
We understand your work has expanded beyond bridges and into tower inspections?
Dan: That’s right. Although our original project goal was researching bridge inspections, ODOT has also now asked us to look at inspecting towers. It’s a similar kind of inspection protocol and we had realised—working on bridges—that this technology could be equally useful on our state’s communication towers as well.
When you say communication towers, we are talking about what type specifically?
Dan: The DOT here in Oregon manages a statewide network of communication systems for broadcasting emergency alerts for travelers and inter-agency communications etc. These are big steel towers, up to 200 feet high, and there is an inspection program for them. Staff go out and climb these towers on a regular basis—looking for loose bolts, defects, cracks etc. So we’ve been flying the albris alongside the towers.
What’s kind of nice in the senseFly ground station software [eMotion] is that you have a cylinder that you can place when mission planning. This calculates all the waypoints that need to be flown to capture the pictures, with the drone flying a series of circles around the tower. We have been impressed, like the DOT, when building 3D point clouds and 3D models from those images.
Planning the inspection of an Oregon communication tower using the Cylinder mission block function inside the albris drone’s eMotion software.
One of the albris’ high-resolution RGB images of a comms tower.
The DOT hadn’t thought about that much, as their original goal was to capture high-res still images to check for defects, but when they realised we could get a 3D model—in effect a digital database of a structure—with the exact geometry of the object, that was something they were really excited about.
The DOT’s original goal was the capture high-res still images to check for defects, but when they realised we could get a 3D model—in effect a digital database of a structure—with the exact geometry of the object, that was something they were really excited about
A drone-sourced 3D point cloud showing communication and cell phone towers in Washburn Butte, Oregon.
Were you conducting these drone operations yourselves, or was there a commercial partner organisation involved?
Mark: Yes, we partner with a company called VDOS Global, a major UAS inspection company. They are our private sector partners on UAS operations. They worked with us on the tower inspections. They are now looking at partnering with us now on flying inside facilities, such as inspecting large tanks in paper mill plants. This idea is really driven by all the sensors that the albris drone has. With its ultrasonic sensors, their distance readings are extremely useful tools. And the ability to fly without GPS assistance is something we really need.
are now looking at partnering with us now on flying inside facilities, such as inspecting large tanks in paper mill plants
Should our readers want to dig into more details of your drone inspection work, has OSU published anything on this topic that they could hunt out?
Dan: We published a conference paper [read it here], which we presented at the 2016 ASCE Geotechnical & Structural Engineering Congress. That paper was based on our first experience flying one of the bridges in our project with the DJI quadcopter.
As a next step, we will write a full technical report that we’ll submit to ODOT. That will be after our full, two-year study, which we’re only eight months into now, meaning that report will be finished in late 2017.
Mark: In the meantime, I just returned from the Wyoming UAV Symposium where Curtis Clabaugh of the Wyoming DOT told me that this type of research— using UAS for inspection purposes—is of big interest for lots of DOTs.
This July our campus is also hosting a committee meeting in Corvallis, with lots of DOTs from around the U.S. due to attend, looking at a lot of geospatial technologies, including our project. This conference will be for the AFB80 committee of the Transportation Research Board (TRB). The AFB80 committee is focused on geospatial data acquisition technologies for transportation design and construction.
Mark, Dan, thanks so much for your time today.
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