Tag Archives: MnDOT

Evaluating a New Low Slump Concrete for Bridge Decks 

For over 30 years, MnDOT has used the same low slump concrete overlay mixture to extend the service life of bridge decks. However, MnDOT suspected that changes in the materials used in the mixture over time may have contributed to increased cracking. This project evaluated a new mixture design, with and without glass fibers, to reduce cracking, improve sustainability and lower costs.

Continue reading Evaluating a New Low Slump Concrete for Bridge Decks 

New Project: Design guidance and best practices for the use of light fill for sustainable road construction

Lightweight Fill (LWF) materials—including Tire Derived Aggregates (TDAs), expanded shale/clay, foamed glass, and recycled glass aggregates—show strong potential for sustainable road construction, yet important knowledge gaps remain. Their environmental impacts, long‑term performance, and construction requirements are not fully understood, especially under Minnesota’s freeze‑thaw cycles and high groundwater conditions. Concerns such as leachate production, potential trench settlement, and challenges faced by local road departments highlight the need for further investigation.

This research seeks to address these gaps by reviewing existing practices, evaluating both environmental and mechanical performance, and developing data‑driven recommendations for using LWF materials in road construction. A detailed assessment will help clarify how these materials behave in pavement structures and embankments and how they interact with water‑sensitive environments. A decision matrix will be used to compare LWF materials and support future project planning.

To achieve these goals, the study will evaluate environmental impacts such as leachate risks, analyze long‑term structural integrity, and conduct Life Cycle Assessment (LCA) and Life Cycle Cost Analysis (LCCA) to assess sustainability and financial feasibility. The research will also develop recommended construction techniques that improve performance and support Minnesota’s climate goals and broader sustainability initiatives.

“Lightweight fill materials show promise for sustainable road construction, and Minnesota looks to learn from what has been done previously,” said Andrew Witter, Sherburne County Public Works Director and County Engineer. “This project will evaluate how these materials behave in local conditions and develop guidance for local counties and cities. The results will help agencies make informed decisions for the benefit of the transportation infrastructure in Minnesota.”

The Objectives:

  1. Document existing research and practices related to LWF materials in road construction.
  2. Evaluate the environmental impacts of LWF materials, focusing on leachate risks and interactions with water-sensitive environments.
  3. Analyze the long-term performance and structural integrity of LWF materials in both pavement structures and embankments.
  4. Compare LWF materials in a decision matrix to guide future project decisions.
  5. Perform Life Cycle Assessment (LCA) and Life Cycle Cost Analysis (LCCA) to assess the sustainability and financial feasibility of LWF materials.
  6. Provide recommendations to develop construction techniques that optimize the use of LWF materials and align with Minnesota’s climate goals and broader sustainability initiatives.

Project Details:

  • Estimated Start Date: 06/25/2025
  • Estimated Completion Date: 06/30/2027
  • Funding: Local Road Research Board
  • Principal Investigator: Michele Lanotte
  • Co-Principal Investigators: Angela Farina
  • Technical Liaison: Andrew Witter

Details of the research study work plan and timeline are subject to change.

To receive email updates about this project, visit MnDOT’s Office of Research & Innovation to subscribe.

New Project: Does lowering speed limits reduce driver speeds on urban streets?

In 2019, the Minnesota Legislature passed a law reducing barriers for cities to systematically lower speed limits. The City of St. Louis Park followed this guidance by reducing speed limits in 2021, but initial speed data collected before and 6–8 months after the changes showed little to no short‑term impact. Because driver behavior is habitual and may change slowly, advocates suggest that greater reductions in operating speeds may emerge over time, highlighting the need for repeat monitoring between 2025 and 2027.

This study aims to evaluate whether longer‑term changes have occurred 2–4 years after the initial reductions, while also examining other Minnesota agencies that have implemented or are considering reduced speed limits. The research will gather both measured and anecdotal data, assess “after” speed conditions where needed, and analyze how effectiveness varies based on roadway characteristics and any accompanying speed reduction countermeasures. These efforts address lingering questions about how speed limit changes influence driver behavior and roadway safety over time.

Understanding speed is critical because it directly affects the safety of all road users. According to Minnesota Motor Vehicle Crash Facts 2022, speeding was the leading cause of traffic fatalities, contributing to 130 of the state’s 444 deaths. By identifying agencies that have reduced speed limits, evaluating short‑ and long‑term impacts, and analyzing site‑specific factors, this research will produce guidance to help Minnesota road agencies assess and implement effective speed limit reductions.

“There is renewed interest in lower speed limits on municipal-type streets,” said Victor Lund, traffic engineer with St. Louis County’s Public Works Department. “The objective of this research is to better understand the intersection of speed limit policy, driver behavior and safety, which will result in guidance to better inform policies, practices and speed limits that support safer streets.”

The Objectives:

  1. Identify local agencies in Minnesota that have implemented reduced speed limits or may consider implementation along with any speed reduction countermeasures that have been implemented with the reduced speed limits.
  2. Evaluate the short-term and long-term effects of speed limit reductions implemented in Minnesota through the collection and analysis of speed data.
  3. Assess how these effects vary based on site characteristics or speed reduction countermeasures that were implemented in coordination with the reduced speed limit.
  4. Based on the findings, develop a summary document to aid Minnesota road agencies in assessing potential speed limit reductions.

Project Details:

  • Estimated Start Date: 06/25/2025
  • Estimated Completion Date: 06/30/2027
  • Funding: MnDOT and Local Road Research Board
  • Principal Investigator: Peter Savolainen
  • Co-Principal Investigators: Tim Gates
  • Technical Liaison: Victor Lund

Details of the research study work plan and timeline are subject to change.

To receive email updates about this project, visit MnDOT’s Office of Research & Innovation to subscribe.

Evaluating the Use of Stabilizers on Gravel Roads 

Gravel roads often experience significant deterioration that requires costly maintenance. To mitigate this deterioration, transportation agencies can apply chemical stabilizers to improve aggregate cohesion. This project examined the mechanical, environmental and economic performance of five gravel stabilizers and three application methods to determine the best options for reducing deterioration.

Continue reading Evaluating the Use of Stabilizers on Gravel Roads 

Protecting Wildlife Along Minnesota Roads

This week is Wildlife Casualty Count Week of Action in Minnesota. It highlights the impacts transportation systems have on wildlife and raises awareness of wildlife deaths resulting from vehicle collisions. Information about this effort can be found at: Wildlife Casualty Count Week

At MnDOT, we are committed to protecting wildlife through established practices and thoughtful planning. MnDOT works to minimize and mitigate impacts to protected fish, wildlife, and plant species in the design and construction of transportation projects. Read more about MnDOT’s commitment to protected species here: Wildlife – Environmental Stewardship

MnDOT’s Office of Research & Innovation supports research projects that advance wildlife protection and environmental conservation. These projects help inform how wildlife considerations are incorporated into transportation planning and construction. Explore projects guiding this work below:

Follow MnDOT’s Office of Research & Innovation to receive the latest updates in transportation research.

Rough roads? How everyday cars might help flag trouble spots

Reprinted from CTS News, May 11, 2026

To assess pavement conditions throughout the state, the Minnesota Department of Transportation (MnDOT) uses a van specially equipped with advanced technology that measures roughness, cracking, and other signs of distress on a roadway’s surface. That system has its limitations, however. The vans cost about $800,000 each, and the data collection requires extensive coordination, trained personnel, and sensitive equipment that is limited to operating in warmer summer months. In addition, the data collection takes place once a year on MnDOT routes and every other year on County State Aid Highways.

van equipped with technology to measure pavement conditions
Mn/DOT’s Pathway Services, Inc. Digital Inspection Vehicle (DIV)

Could there be a more efficient and more timely way to assess the state’s road pavement conditions? To find out, researchers at the University of Minnesota (UMN) explored whether data already being generated by everyday vehicles could enhance MnDOT’s current method. 

To test this, UMN researchers equipped study vehicles with a simple plug-in scanner that captured onboard diagnostics data, explains CTS scholar Raphael Stern, the project’s co-investigator and UMN associate professor of civil, environmental, and geo- engineering. Modern vehicles already have sensors that collect this data, which can be used to monitor and optimize vehicle performance. That same data could provide clues to how a vehicle is responding to pavement beneath it, he says.

“If we could show that this can be done in Minnesota, MnDOT or local agencies can implement this technology,” says lead investigator and CTS scholar Mihai Marasteanu. “They could have a very good idea about the conditions of pavement every day—not just once a year.”

For this project, researchers adapted methodologies from Denmark’s Live Road Assessment (LiRA) project, considered to be the most comprehensive effort to use onboard vehicle sensors for continuous pavement monitoring. That initiative provided insights into both the technical feasibility and practical challenges of extracting meaningful pavement quality metrics from standard vehicle data.

Researchers tested a similar approach on three routes in Minnesota to capture a diverse range of pavement conditions under real-world driving scenarios. One route was a 15-mile loop in the northeast Twin Cities metropolitan area that covered urban and suburban road segments with consistent traffic flow. Another was a 96-mile loop between Minneapolis and Northfield, comprising a mix of urban, suburban, and rural roadways. The third was the 2.6-mile loop at MnROAD, MnDOT’s research facility near Albertville.

The plug-in scanner collected data on vehicle location, speed, and 3D acceleration; the last measures the intensity and complexity of vibrations transmitted from the road through the vehicle’s suspension system.

Across the three routes, researchers collected more than 9,000 data points. Machine learning models used 694 data values to predict pavement quality using the International Roughness Index (IRI) for a given pavement section.

Researchers compared and validated predictions against data from MnDOT and a commercial pavement‑monitoring system. Results demonstrated a correlation across diverse road conditions, although accuracy decreased in areas where pavement conditions changed quickly or road surfaces had defects. Predictions were also more accurate on highway segments than local roads because of variable urban driving environments.

Of the eight learning models evaluated, one achieved 94 percent accuracy on predicting pavement roughness. The performance of each model varied based on environmental factors, data collection conditions, and road types.

The research successfully demonstrated that vehicle sensor data can effectively support continuous infrastructure monitoring, Marasteanu says. “It could save money in the long run and give a much more accurate representation of pavement conditions over the entire year,” he notes.

The project, funded by MnDOT, included implementation guidelines for large-scale deployment, equipment standardization protocols, data-processing pipelines, and risk-mitigation strategies.

MnDOT is now exploring how to extend the research beyond the study vehicles, says Curt Turgeon, director of MnDOT’s Office of Materials and Road Research. One way will be to use commercial data sources that already collect similar information from everyday vehicles. For example, NIRA Dynamics, headquartered in Sweden, partners with automakers Volkswagen and Volvo to collect anonymized sensor data from consumer vehicles. These data streams are captured continuously throughout the year.

“MnDOT has a contract with NIRA to determine how this data might enhance our pavement management decisions as well as potentially document snow and ice response,” he says. “They also have a module that may flag potholes or other in-road hazards based upon vehicles swerving.”

—Peter Raeker, contributing writer

Related reading

Continue reading Rough roads? How everyday cars might help flag trouble spots

CTS Webinar: How Infrastructure Shapes Driver Behavior and Pedestrian Safety

About the Event 

Improving pedestrian safety requires a deeper understanding of how people interact with roadway design and infrastructure. This webinar will highlight two recent research efforts examining how transportation infrastructure influences driver behavior and pedestrian safety outcomes.

Curtis Craig, a research associate in the Human Factors Safety Laboratory, will present findings from two complementary studies examining infrastructure at intersections. The first study explored how right turn lane configurations affect pedestrian safety using a combination of behavioral analysis and multiple research methods. The second project examined how drivers and pedestrians respond to different infrastructure treatments and how those designs influence behavior in real-world environments.

These study findings offer transportation agencies, planners, and engineers practical considerations as they work to create safer and more accessible pedestrian environments.

Registration and More

This webinar is free, but registration is required. Visit the event web page to register and for more information. 

Related Reading

Active Research by Curtis Craig

Analysis and Risk Management of Motorcycle, Bicycle, and Pedestrian Crashes in Minnesota

Addressing disparities through more equitable transportation planning

Reprinted from CTS Catalyst April 16, 2026

Transportation capital investment planning plays a vital role in shaping the future of infrastructure—but often leaves people with disabilities, youth, older adults, people of color, and disadvantaged communities underserved. A recent UMN research project aimed to gain a better understanding of how to include equity in planning and decision making.

To gain a better understanding of how to include equity in planning and decision making, a recent research project explored this complex topic through a literature review, statewide survey, and analysis of case studies. This research, sponsored by the Minnesota Department of Transportation (MnDOT) and the Minnesota Local Road Research Board, resulted in considerations and strategies, including a toolkit, to increase community engagement and guide future transportation development for Minnesota localities and Native nations.

Camila Fonseca-Sarmiento, director of fiscal research for the Institute for Urban & Regional Infrastructure Finance at the University of Minnesota’s Humphrey School of Public Affairs and a CTS scholar, led a team of researchers through a review of case studies for which equity was included in capital investment planning. As in other states and localities across the United States, the team found that the definition of equity and the goals of equity-related funding ranged widely across Minnesota’s counties, cities, and Native nations.

Incorporating equity factors in transportation investment planning in Minnesota has occurred through small, incremental changes. A few jurisdictions have already integrated equity into their planning efforts, while some others are in the process of doing so. Jurisdictions with a more comprehensive equity framework are those in which equity is part of a local initiative, compared to those who mentioned equity efforts as a response to federal funding requirements, such as Title VI of the Civil Rights Act of 1964 and the Americans with Disability Act.+6

Minnesota brings an additional set of equity considerations through the inclusion of the state’s 11 Native nations. These Ojibwe and Dakota communities and reservations share many of the same needs and challenges as other localities but also possess unique cultural considerations, including sovereignty, sacred sites, and environmental protection. For example, on a practical level equity for Native nations means fair employment—equitable job opportunities, wages, and hiring preferences for tribal members to ensure benefits stay within the tribal nations on or near reservations. On a cultural level it means dual language signage for English and Ojibwe or Dakota on roads and highways that traverse Native lands.

“Equity is not a one-size-fits-all approach,” Fonseca-Sarmiento says. Engaging community members early in the planning process helps planners understand transportation needs beyond roadway investments—such as a community’s historical experience, culturally specific needs, and current gaps. The research findings offer guidance on how to gather local input through surveys and in-person meetings guided by trained staff. 

The transportation capital investment planning and decision-making process consists of several phases where equity could be integrated: identifying projects, prioritizing capital investment projects through multi-step processes, and selecting projects for funding through community advisory committees.

A toolkit developed by the researchers could help improve communication and engagement with underserved communities. Its two key tenets are that agencies need to proactively reach out to the community, and trust-building is essential for effective relationships.

In addition, Dillon Dombrovski, deputy public works director/city engineer with the City of Rochester and the project’s technical liaison, says the community engagement toolkit “provides effective guidance to combine community input with supporting data to invest in more equitable transportation projects.”

Fonseca-Sarmiento says it’s also critical to listen and then include diverse perspectives in the final transportation plan. “Engaging local stakeholders in the planning process but then leaving them out of the finished project decreases trust and limits future engagement,” she says. “Overall, having regular community engagement for identifying transportation capital investment projects can also help prevent perpetuating past inequities.”

Amy Goetzman, contributing writer

Related reading

CTS Webinar: Infrastructure Materials and Performance

Tuesday, April 21, 2026
noon–1:30 p.m. CDT, Virtual

About the Event

Understanding how infrastructure materials perform over time is critical to making informed design, construction, and maintenance decisions. This webinar will feature two recent University of Minnesota research efforts that examined the real-world performance of commonly used transportation infrastructure materials.

Continue reading CTS Webinar: Infrastructure Materials and Performance