In the above video, University of Minnesota-Duluth Associate Professor Ryan Rosandich tests a prototype of a robotic arm he developed to paint messages and markings on roadways. He calls the machine “The MnDOT Robot.”
During a test run in October 2015, the MnDOT robot painted a right-turn arrow and the word “ahead” on pavement at MnDOT’s Pike Lake station in Duluth.
Rosandich hopes commercial companies will show an interest in further developing his proof-of-concept technology into something that road authorities can use regularly to make work easier, faster and safer for their employees.
Companies interested in commercializing this technology can contact Andrew Morrow at email@example.com.
Editor’s Note: The paint used in the above demonstration was diluted due to the cold weather at the time of the demonstration and does not reflect the condition of the paint expected in a typical application.
As the flying electronic devices became easier to use and less expensive, all sorts of individuals, businesses, nonprofit groups and government organizations – including the Minnesota Department of Transportation (MnDOT) – are exploring ways to use them.
This past summer, MnDOT began researching how to employ these unmanned aerial vehicles, or UAVs, to someday help inspect the state’s many bridges.
“That day may still be far off, but our initial project was an encouraging first step,” said Jennifer Zink, MnDOT bridge inspection engineer. “Phase 2 of the project will better provide details as to methods, criteria and cost effectiveness for how to apply drone technology best to bridge inspection.”
The research team tested drones this past summer while inspecting four Minnesota bridges (in Chisago County, Olmsted County, Morrison County and near Stillwater) specifically selected for the study after an extensive evaluation and FAA approval.
Zink and her colleagues wanted to investigate whether drones could help MnDOT decrease the rising costs of bridge inspections and collect more detailed information. Drones could also minimize the risks for bridge inspectors, who currently use rope systems and special inspection vehicles to access hard-to-reach areas. Using a drone to gather images could keep inspectors out of harm’s way and inspection vehicles out of active traffic lanes.
“The goal of the project was to study the effectiveness and possibilities of using UAVs to aid in bridge inspection work, typically in gathering images without the use of an under-bridge inspection vehicle and in areas where access is difficult or not safe for an inspector,” Zink said. “There is no substantive guidance in existence for this application of this evolving technology. This initial effort was to gain a better understanding of potential capabilities, processes and planning best practices.”
Before simply launching drones and collecting bridge data, the research team reviewed current FAA rules and applied for the necessary exemptions. Approval was granted, but only for the use of an Aeryon Skyranger drone. Even though exemptions for several models were submitted to the FAA, none were approved in time for the field study.
Once in the air, the drone suitably performed a variety of inspection functions that didn’t require a hands-on physical inspection. Researchers tested the drone’s ability to gather high-quality still images and video footage of bridges. They also collected data from infrared cameras. In addition, the drone provided the ability to capture data needed to construct maps of bridge areas and 3D models of bridge elements.
“The images, including infrared images to detect deck trouble spots, obtained from the drone correlate to the findings in the bridge inspection reports for specific bridge elements,” Zink said.
Missing from the research were images of the underside of bridges. The drone model used in the study wasn’t able to shoot images upward from beneath a bridge, and inspectors identified that as a key feature along with the ability to operate without a GPS signal.
“The drone we used in this project was not completely ideal for an entire gathering of imagery for all bridge inspection elements as it was limited to GPS signal capability,” Zink said. “However, it did give us an idea of what a drone could provide, what the limitations were, and what features we would like to see on newly available UAV models. Unfortunately, our hands were tied with obtaining FAA exemptions only for the particular model used in this project within the funding timeframe.”
Conclusions and recommendations
The project’s final report listed several conclusions, including that drones can be used safely during bridge inspections and that risk to both the inspectors and public is minimal.
“Due to the successful outcome of the initial project, we have a better understanding of the drone capabilities we would like to use during an actual scheduled bridge inspection,” Zink said. “The drone that will be used in Phase 2 is specifically designed for inspection of structures. Several goals exist for the Phase 2 research project, and if we can accomplish them, they will decrease MnDOT’s costs and increase bridge inspection abilities. It could improve inspection data collection for local agencies as well.”
The researchers recently were notified that they received funding for Phase 2 of their project, which is expected to start later this fall.
Roadways for humans can sometimes create roadblocks for fish, but researchers hope to establish a set of culvert design practices to help aquatic creatures get where they’re going.
Many fish depend on mobility along a river for feeding and spawning. Where roads meet rivers, however, culverts can block fish and other aquatic organisms that can’t navigate changes in current, lighting and other factors.
Waterway barriers threaten an already endangered species of minnow known as the Topeka shiner (pictured above). It can also be a big problem for economically important fish such as trout or northern pike. That’s why the Minnesota Department of Natural Resources prefers building bridges to culverts.
However, bridges are not always economically feasible, and so MnDOT is working closely with the DNR to develop culverts that protect both public safety and the environment.
Recent research suggests that installing boxed culverts differently could greatly improve fish passage.
Culverts are typically placed a little below the streambed with the expectation that the stream flow will naturally fill them with sediment. Researchers tested that assumption and found it to not always be accurate.
“We found that pre-filling the culvert with sediment that replicates the streambed as part of the installation process helped prevent upstream erosion and the development of vertical drops that can become barriers to aquatic movement,” said Jessica Kozarek, a University of Minnesota research associate. “In addition, pre-filling the culvert helped ensure the sediment remained inside the culvert flows were high and water moved quickly during rainstorms.”
MnDOT has been working with the DNR to identify the conditions that determine whether a newly installed culvert will naturally fill with sediment, replicating surrounding streambed conditions, or whether a stream’s water flow will transport sediment out of a culvert.
Using an experimental flume at the University of Minnesota’s St. Anthony Falls Laboratory, researchers tested MnDOT’s standard box culvert design under a variety of stream conditions.
Laboratory simulations suggest that filling a culvert with sediment at installation, rather than allowing it to fill over time is, with some exceptions, generally the best approach for low- and moderate-grade streams. Additionally, steep, fast-moving waters require a filled culvert with structures such as larger rocks to keep sediment in place. These structures also create steps, pools and riffles that enable fish to rest as they move upstream.
MnDOT will use this latest research, along with conclusions from other recent studies, to create a guide for fish-friendly culvert designs.
“Of all the things we’ve studied, there are maybe three or four research projects. This manual will pull it all together,” said Petra DeWall, state waterway engineer at the Minnesota Department of Transportation.
Further research is underway to determine whether aquatic organisms are deterred by low light conditions in long, dark culverts. Researchers are also looking into whether mussel spat rope could be used to create a rough bottom to reduce water speed in culverts with no sediment.
A handful of county highway department employees in the Rochester area gathered recently at the Olmsted County Public Works Service Center for a presentation and live demonstration by University of Minnesota Research Fellow Brian Davis about his team’s work involving light detection and ranging – or LiDAR.
“LiDAR is like radar, but with light,” Davis said. “It gives you information about what’s around the sensor.”
Davis and his fellow researchers have outfitted a sedan with special LiDAR equipment and other technology that is capable of capturing a 360-degree, 3-D view of a scene in real time.
“We use the car as a test bed,” Davis said. “We have a lot of different types of sensors on the car that we use for the different projects that we’re working on. Right now we have a LiDAR sensor on top. Sometimes we have a high-accuracy GPS receiver in there. We have a cellular modem. We have a handful of inertial sensors. So it’s a lot of different stuff that we use to cater to the application.”
For his presentation, Davis showed the attendees some of the data his team had already collected.
“We showed a handful of pre-collected data at a handful of intersections around Rochester and Minneapolis,” Davis said. “What it shows is the point cloud collected by the sensor – just the raw point cloud with no post-processing done. In that information you can see people moving through it, cars moving through it, buses and light rail trains.”
After the presentation, Davis led the group to the parking lot for a close-up look at the technology and how it collects data and displays that data in real time. Le Sueur County GIS manager Justin Lutterman was among those who could envision possible applications for LiDAR.
“It’ll be interesting to see where this can go,” Lutterman said. “I’m sure the private industry will take off with this and emergency management, or the sheriffs and ambulances, would appreciate this kind of technology on their vehicles for a situation they might have to recreate. Roads and traffic designers would be able to monitor their resources, pavements, traffic counts and things like that.”
Over the coming months, researchers will gather more data to develop a workshop for county personnel interested in learning more about LiDAR and how it can be applied in their transportation systems.
“The next steps for this project are to collect some data with the car at intersections. Then we can use that information to fine tune our algorithms,” Davis said. “What the algorithms are going to do is take that raw data and give us useful information, like the number of cars, or the time a car passes through an intersection. That all feeds into the workshop we’re developing. The workshop is going to be for county GIS workers, traffic engineers and county engineers who are interested in learning about these technologies.”
Bridges over Minnesota waterways need to be protected from currents by a field of interlocking angular rocks called riprap. Without these rocks along the abutment, moving water could wear away the soil that supports a bridge’s foundation. The faster the water, the larger the riprap must be to provide adequate protection.
While some parts of Minnesota have quarries rich with angular rock, other parts don’t – particularly the northwest and western regions. Bridge projects in those areas sometimes resort to the expensive practice of trucking in stones. Other times field stones are used, but they are less effective and must be replaced more often.
There soon could be a better option thanks to research coordinated by the Minnesota Department of Transportation and funded by the Minnesota Local Road Research Board.
At a few test sites around the state, researchers have used a grout mixture to cement smaller, rounded rocks together at a bridge abutment. Once applied to the rocks, the mixture forms what is called “matrix riprap.” The concept is in use in Europe for many bridge piers, but MnDOT was more interested in learning how it could be used on bridge abutments.
Matrix riprap is currently in use in Minnesota at the following bridges:
Highway 23 over the Rum River in Milaca
Highway 8 over Lake Lindstrom channel in Lindstrom
Prairie Road over Coon Creek in Andover
In May 2012, matrix riprap was placed at the Milaca bridge, which sits alongside a high school. Researchers hoped the use of matrix riprap would prevent vandals from removing the riprap rock and throwing it into the river. According to Nicki Bartelt, a MnDOT assistant waterway engineer, the matrix riprap has proven to be extremely strong and effective.
“Not only is matrix riprap significantly stronger than regular riprap, but it helps prevent vandalism as well,” Bartelt said. “The Milaca installation has been in place for three years now. It looks pretty good and it’s weathering well.”
In the lab, matrix riprap held up extremely well on mechanical pull tests and hydraulic flume tests. In fact, researchers were unable to determine the matrix riprap fail point on many tests, even after applying 10 times the shear stress that regular riprap can withstand. Matrix riprap was tested with both angular and round rock with no change in performance.
A new matrix riprap installation recently went in on the Highway 95 bridge over the Rum River in Cambridge. Later this summer, plans call for an installation on the Highway 60 bridge over the north fork of the Zumbro River in Mazeppa.
“The Highway 60 bridge is being replaced, and the river there has extremely high velocities, so we’re using the matrix riprap instead of regular riprap just because of the size of rocks that would be needed,” Bartelt said.
At least two more installations are planned for 2016. In the future, researchers plan to determine the fail point for matrix riprap. They also hope to study potential environmental effects the grout may have underwater.
MnDOT has also worked with local governments that have tried matrix riprap for themselves. One municipality is trying it as a heavy duty erosion control measure. The concept is catching on outside Minnesota as well.
“We have gotten a lot of inquiries from other states, and we have lent out the spec a lot,” Bartelt said. “Iowa, New Hampshire, Maine, Indiana, Wisconsin and Illinois are among the states to express interest. We have talked to a lot of people about it, so they tend to use our research.”