By Joseph Palmersheim
Engineer Thomas Burnham (right) explains a Portland cement concrete patch at the MnROAD open house on Aug. 8. Longer-lasting patches on Minnesota's PCC pavements will reduce the need for lane closures, user delays and maintenance costs. This can increase the availability of state district maintenance staff to perform other duties. Photo by Micaela Resh |
In 1993, Gregory Johnson was working at the University of Minnesota on a project funded by MnDOT. Through those connections, he was offered a position as a MnDOT soil scientist working on something new - the MnROAD project.
“The project was so different from a typical MnDOT project,” said Johnson, who now serves as an assistant bituminous engineer with the Office of Materials Road and Research. “People were excited about what we could learn.”
More than two decades later, people are still excited about MnROAD. Nearly 120 people attended an open house Aug. 8 to celebrate its 25th anniversary. The Otsego-based facility is a pavement test track made up of various research materials and pavements owned and operated by MnDOT, working with its National Road Research Alliance partners and other researchers around the world. Through research and experimentation, MnROAD finds ways to make roads last longer, perform better and cost less to build and maintain. These roads can also be built faster and have minimal effect on the environment.
MnROAD has more than 50 unique test sections on various roadway segments: a 3.5-mile section (I-94) mainline; a 3.5-mile section of the original westbound lane of I-94; and a 2.5-mile low-volume road. Researchers use all three of these sections to collect detailed asphalt, concrete and base material performance data with the help of nearly 6,000 pavement sensors located in each test section.
“We’re trying to solve questions about what kind of materials we should use in our roadways,” said Ben Worel, MnROAD operations engineer. “There’s always new advancements in materials, additives, new ways of doing things. We try to test these things on small sections before doing it across the system, and we’re also working with other states and groups to come up with ways to manage our roadways in the most effective manner we can. We can take risks here. If things work, they can save us lots of money on the whole system.”
MnROAD was constructed from 1990 through 1993 at a cost of $25 million, funded by state and federal sources. Like Johnson, Thomas Burnham was a University of Minnesota student who ended up joining MnDOT. He worked on the project starting in 1991.
“It sounded interesting,” he said. “I collected and organized the hundreds of soil samples and tests during the construction of the first phase of MnROAD. I also helped out with installation of the numerous sensors embedded into the roadway. Constructing and instrumenting such a large road research facility was not something that was commonplace. Because the site has a high water table and silty-clay soils, up to two weeks of delay would take place every time it rained, [which meant] waiting for the sections to dry out before moving on to the next layer. This, and the need to connect 23 cabinets and hundreds of miles of sensor wire, is why it took over three years to construct five miles of pavement.”
Research expanded significantly in 2017 when test sections were installed featuring experiments designed by the National Road Research Alliance, a cooperative initiative that includes eight state DOTs and more than 50 private organizations.
MnROAD studies were estimated to save $33 million per year during Phase I (1994-2007) and $10.3 million per year during Phase II (2007-2017).
“Both outweigh our initial investments into MnROAD and its research,” Worel said. “The future is bright for the upcoming years with MnDOT and its NRRA partners.”
Some of the discoveries or developments from MnROAD research include:
- Development of setting seasonal load restrictions (winter overloads/spring load restrictions)
- Development of a process to select the right asphalt binder to reduce thermal cracking for asphalt roadways
- Reduction of concrete thickness for future roadways (past designs were too conservative, Worel said)
Any data collected at MnROAD is public, meaning it can be shared with universities, other DOTs and industries.
In addition to being the longest-running facility of its kind, MnROAD is the only one run by a state DOT. It’s also the only one that works with both asphalt and concrete. The other large scale test facility is the National Center for Asphalt Technology at Auburn University, which runs a test track in Opelika, Ala. MnROAD and NCAT work very closely on a number of national projects, Worel said.
The relative scarcity of facilities like MnROAD puzzles Dr. Matthew Witczak, who served as a consultant to assist in the overall conceptual design of the facility in 1987.
“To me, reflecting upon my nearly 60-year career in the pavement community, MnROAD was an absolutely ingenious idea that merged together the practical necessity of conducting advanced research studies with actual field performance monitoring,” Witczak said. “This, by far, is the biggest advantage a facility like MnROAD offers. It is important for the traveling public to know and understand that design and prediction of transportation facilities is a very complex engineering task, and we still do not thoroughly understand, nor can we accurately model, all of the actual pavement damages that do occur in practice. In order for engineers to gain knowledge and a better understanding of the behavior of pavement systems, the public must understand we can only gain a better understanding of the ‘state of the art’ by learning from actual, controlled and monitored failures.”
Since its inception, MnROAD has grown from a Minnesota-based facility to a Minnesota-based resource. The partnership with NRRA has connected it to seven state DOTs (Michigan, Wisconsin, Iowa, Illinois, North Dakota, Missouri and California) and more than 50 industries, associations and academic institutions.
"NRRA helps facilitate the discussion on innovation and what the future focus should be for developing research needs for the group,” Worel said. “It’s been very positive in supporting our partnerships and has helped MnROAD develop a broader perspective on advancements and where we need to go in the future.”
Burnham says he was lucky to stumble into a unique career with the opportunity to share knowledge with practitioners around the world.
“I hope Minnesotans appreciate the jewel they have with the MnROAD facility,” Burnham said. “Given our extreme climate and growing traffic volumes, it has been a valuable tool in extending the life of our pavements, as well as saving millions of taxpayer dollars. I hope to continue using the facility to continue down that path long into the future.”
More information on MnROAD
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