Tag Archives: research

Materials and Construction, research

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

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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.

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

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.

research, Traffic and Safety

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

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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.

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

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.

Materials and Construction, research

New Project: Are Current Rigid Pavement Roundabout Designs Working in Minnesota?

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As roundabouts become more commonplace in Minnesota, the role they play in the improvement of traffic flow and safety increases. Although rigid roundabouts were originally designed with the assumption that they would behave like rigid pavements on motorways, their performance can be affected by the unique traffic patterns and stresses they experience. The irregular shapes of their concrete slabs face distinct braking, stopping, accelerating, and drainage conditions, which increase the likelihood of cracking and other forms of pavement distress. Heavy trucks navigating sharp curves add additional strain. While concrete pavements are generally durable, pavement wear is greatly affected by elements characteristic of roundabout design.

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

This research seeks to evaluate and improve the performance of concrete roundabouts in Minnesota, with the aim of extending their service life and increasing their overall effectiveness. The project will start with a comprehensive field survey throughout the state, collecting information on different roundabout designs and documenting the types and levels of pavement distress present. The data will be analyzed to identify performance trends and gain a clear understanding of each design’s advantages and shortcomings. In addition to the field investigation, the study will conduct an in-depth structural review of factors such as joint spacing, dowel bar placement, slab geometry, and drainage features.

Using insights from both the field observations and structural analysis, researchers will propose design strategies to improve the durability of Minnesota’s roundabouts. These recommendations have the potential to strengthen roundabout design practices and contribute to a safer, more dependable transportation system.

“With the rapidly growing number of concrete roundabouts being constructed throughout Minnesota, it is important that we monitor their performance and adjust our design methodologies to ensure that the traveling public can utilize them safely, while maximizing the investments spent on their construction and maintenance,” said Thomas Burnham, research operations engineer with MnDOT’s Office of Materials and Road Research. “This research project is set up to accomplish these goals.”

The Objectives:

  1. To measure rigid pavement roundabout performance for various traffic loads and design features.
  2. Using pavement system performance data, identify any design changes that could minimize maintenance.
  3. Create state-of-the-art guidelines and recommendations for improving the design, function and lifespan of concrete roundabouts in Minnesota.

Project Details:

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.

research, Traffic and Safety

New Project: Can Enhancing Color on Dynamic Message Signs Improve Clarity and Safety?

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The majority of MnDOT’s dynamic message signs (DMS) are equipped to produce full color/full matrix messaging. Current signage regulations refer to retroreflective colors for static signs, but MnDOT aims to extend and modify existing standards and guidelines by exploring differences between static signs and DMS.

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

This research will systematically explore and optimize the use of different colors and color-coding schemes in DMSs to resemble the retro-reflectivity of static signs and examine how legibility, visibility, and effectiveness can be improved. Optimizing DMS colors to mimic retroreflective static sign colors and adapting them to myriad environmental conditions, MnDOT can realize reduced driver distractions, improved information comprehension, and increased safety. The project will also support improved decision-making processes by providing evidence-based guidance for future standards and practices for MnDOT beyond.

A pilot study will be conducted to assess the recommended color settings against benchmark real-world conditions. Empirical data on the new configurations will measure their performance, confirm their effectiveness and identify any adjustments required prior to broader implementation.

“Not all color is created equal! As illustrated in the three graphics below, federal standards for reflective sheeting and striping, NEMA standards for colors, and the triangle of visible light LED lights can produce do not correspond,” said Terry Haukom, senior engineer with MnDOT’s Regional Transportation Management Center. “This variance has caused the signage industry to display colors that meet federal standards but do not look correct to the human eye. In addition to exploring this incongruity, our research is focused on understanding and comparing what typical travelers understand and expect when viewing traffic information on the web, and whether the travel time numbers displayed on our signs can give drivers a better understanding of the travel time to the listed destination if it was displayed with a color scheme that leveraged web-based maps.”

The Objectives:

  1. Standardize the emitted colors from MnDOT’s DMS according to NEMA TS4 and MUTCD specifications, ensuring they match the retroreflected colors of static signs and align with current LED capabilities
  2. Document the public’s perception of optimum color if different from standards based on human factors feedback
  3. Document the public’s perception of dark pixel around graphics on emitted colors on DMS
  4. Research and document the public’s perception of emitted colors on DMS compared to static sign messages, and explore the incorporation of web-based travel time map colors to enhance visibility and clarity, especially with colors like amber

Project Details:

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.

Policy and Planning, research

Preparing the Transportation Workforce for Emerging Technologies: A Guide

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Transportation agencies are facing rapid technological change—from artificial intelligence and machine learning to connected and automated vehicles, data governance, cybersecurity, advanced communications, and emerging analytical tools. These technologies are transforming how transportation systems are planned, operated, and maintained, while simultaneously reshaping workforce needs. This guide from the National Cooperative Highway Research Program offers practical strategies and resources to recruit, develop, and retain a workforce capable of adopting and leveraging emerging technologies.

Industry Challenges

As new technologies proliferate, agencies struggle with a number of overlapping challenges.

  • Outdated organizational structures and siloed departments
  • Skill gaps in advanced technical areas
  • Difficulty competing with private-sector salaries
  • Limited awareness of transportation tech careers among students
  • Pipeline shortages due to retirements and evolving skill demands

The guide categorizes these challenges into three core areas: Institutional Agility, Staffing Adaptability, and Workforce Pipeline.

1. Institutional Agility

Agencies must evolve organizational flexibility to integrate new technologies into their existing practices. There are a number of steps they can take to help with this.

  • Build multidisciplinary teams to break down silos and improve collaboration across planning, operations, IT, and field staff.
  • Modernize organizational structures and culture, including job rotations, co-location, communities of practice, refreshed licensure requirements, and skills-based management.
  • Develop business cases for new positions, such as data analysts, AI specialists, cybersecurity roles, and system engineers.
  • Enhance benefits packages beyond salary—highlight flexibility, professional development, hybrid schedules, innovation opportunities, and mentorship.

2. Staffing Adaptability

While the agency must modernize its processes, it must also provide a way for staff to develop the required skills to navigate new requirements. Should they hire, contract, or provide development channels for existing staff? The report has some suggestions.

  • Identify and formalize emerging positions across traffic operations, data analysis, IT/OT, hardware maintenance, policy/innovation, and design/construction.
  • Use a decision tool to determine whether to upskill current staff, hire new staff, or outsource work based on urgency, core function, and internal capacity.
  • Develop and promote new career paths that incorporate technical and soft skills, including leadership, communication, and innovation.
  • Leverage vendor contracts to include staff training, system handoff support, and access to vendor training sessions.
  • Recruit from adjacent industries with transferable skills—IT, telecommunications, military, emergency management, gaming, and manufacturing.
  • Connect staff to professional organizations and national training programs to keep technology skills current.

3. Long-term Workforce Pipeline

In addition to responding to immediate needs in the organization, the agency should look at strengthening the long-term talent pipeline with education partners.

  • Build partnerships with K–12, community colleges, trade programs, and universities through advisory committees, career fairs, mentorship, and public awareness campaigns.
  • Expand internships, apprenticeships, faculty exchanges, and hands-on training opportunities in emerging technology areas.
  • Collaborate on curriculum modernization, integrating interdisciplinary programs that blend engineering, IT, data science, and policy.
  • Invest in or share technology labs, equipment, and research opportunities to expose learners to real-world systems.
  • Support research initiatives that incorporate workforce development, outreach, and student engagement.

Conclusion

Emerging technologies offer transformative benefits for transportation systems but realizing those benefits hinges on the workforce. Agencies must take proactive, structured steps to evolve their organizations, strengthen recruitment and retention strategies, and build sustainable talent pipelines. This guide provides a flexible, practical framework to help you look at your organization and think about how some of these ideas apply to it, and how they may help you develop your own strategy for improving how you prepare for emerging technologies.

Read the complete report:

NCHRP Research Report 1174 (website or PDF)

Additional resources

Environment, research

Protecting Wildlife Along Minnesota Roads

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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:

Goats can play a role in multi-pronged restoration of buckthorn-invaded woodlands | University of Minnesota

Identifying Deer-Vehicle Collision Concentrations in Minnesota

Species From Feces: A New Tool to Identify Bats in Culverts and on Bridges

Assessing a New Tool for Early Detection of Endangered Turtles on Proposed Transportation Projects

Reduce Vehicle-Animal Collisions with Installation of Small Animal Exclusion Fencing

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Policy and Planning, research

New Project: Understanding How Parking Space Requirements Affect Vehicle Miles Traveled

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Minimum parking requirements were established in the mid-20th century to mitigate increased motor vehicle congestion but have the potential to contribute to urban sprawl, hinder development, and curb incentives for drivers to choose alternative travel modes. Eliminating or reducing these requirements can help remove excess parking supply, increase alternative modes such as transit ridership, reduce vehicle miles traveled (VMT), and enhance economic productivity. Decreasing VMTs directly mitigates emissions by reducing car travel distances and many VMT reduction strategies hold additional benefits such as increasing accessibility and reducing traffic congestion.

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

VMT reduction also plays a significant role in Minnesota’s efforts to reduce greenhouse gas emissions from the transportation sector. New legislation passed in 2023 requires reducing VMT up to 20% per capita by 2050. The impacts of parking space requirements or long-term benefits and challenges associated with modifying or removing these requirements have not been studied in Minnesota. This project will investigate, document, and advance the understanding of minimum parking requirements in Minnesota and the region and their impact on VMT reduction.

Researchers aim to establish recommended values based on differing types of land use and community context, e.g., urban, suburban, and rural within Minnesota. Specifically, this project will examine the long-term benefits and challenges presented by reducing and/or removing currently established parking space requirements with new or redevelopment projects, and opportunities for parking space reallocation with existing uses.

“This research aims to fill a critical knowledge gap, will modernize minimum parking requirements reduce vehicle miles traveled, and provide communities with more flexible land‑use options,” said Mark Vizecky, state aid operations engineer, State Aid for Local Transportation at MnDOT.

The Objectives:

  1. Perform literature reviews of historical and current practices, policy and requirements regarding parking space requirements in Minnesota and the Upper Midwest and of current best practices regarding parking space requirements and the impact parking has on land use and travel behavior.
  2. Interview local agencies and the League of Minnesota Cities to gain insight into current parking space practices, policies, and requirements across Minnesota.
  3. Conduct an online survey of business stakeholders to assess the potential economic impacts of parking policy changes regarding customer behavior, business density, operating costs, opportunity cost and sunk cost, and accessibility.
  4. Conduct a travel behavior and mode choice survey using a diverse group of daily commuters from Minnesota’s urban, suburban, and rural communities to understand the influence of parking policies on traveler behavior.
  5. Analyze survey responses using discrete choice modeling to develop utility equations for different parking requirements, which will help predict mode shifts and associated VMT reductions.
  6. Utilize travel demand model data from eight metropolitan planning organizations in Minnesota to assess how changes in parking requirements could impact VMT reduction.
  7. Analyze the sensitivity and data requirements for a parking space requirement that will be effective for local use and develop a toolkit for local municipalities to assess parking needs and the economic impacts of parking policies in local communities.

Project Details

  • Start Date: 06/02/2025
  • Estimated Completion Date: 04/30/2027
  • Funding: Local Road Research Board (LRRB)
  • Principal Investigator: Kakan Dey
  • Co-Principal Investigators: Subasish Das, Ali Zockaie
  • Technical Liaison: Mark Vizecky

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.

Materials and Construction, research

New Project: Using Satellite Technology to Monitor Ground Deformations Adjacent to Roads

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Geohazards generated by ground movements (e.g., landslides, subsidence, sink holes, etc.) cause substantial damage and interruptions to Minnesota’s highway network. Reactive monitoring approaches and borehole-based instrument sensing both have limited spatial coverage and are limited to sites already known to be in distress. This research explores the establishment of continuous satellite-based InSAR monitoring of ground deformations adjacent to roads on a broad geographic scale that would enable detection of pending hazards before they develop into large failures.

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

This warning system will combine data from high spatial resolution InSAR measurements, optical remote sensing data, and deep learning algorithms to automatically detect and continuously monitor deformations across large spatial regions. The research team will create MnDOT training modules to demonstrate the utility of the deformation data and automated warning system.

InSAR monitoring is expected to improve the safety and reliability of Minnesota’s transportation system and reduce costs and delays associated with emergency repairs. It would also support the state’s geotechnical asset management program by assessing the feasibility of InSAR for tracking performance of geotechnical assets (e.g. retaining walls, slopes, pavement foundations, etc.).

“This research project will help us determine if InSAR technology is ready for prime time for transportation agencies as a remote sensing tool to track performance of assets,“ said Raul Velasquez, geomechanics research & deployment engineer at MnDOT’s Office of Materials and Road Research.

The Objectives:

  1. Develop an automated warning system that can alert MnDOT staff of areas where abnormal ground deformation (e.g., landslides, subsidence, and sinkholes) is occurring along Minnesota interstate highways, allowing them to proactively intervene.
  2. Assist MnDOT in continuing to build its geotechnical asset management program by assessing the feasibility of InSAR for tracking performance of geotechnical assets such as retaining walls, slopes, and pavement foundations.

Project Details

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.

Environment, Maintenance Operations, research

Goats can play a role in multi-pronged restoration of buckthorn-invaded woodlands

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Reprinted from MnLTAP News, May 4, 2026

Goats are increasingly being used in efforts to manage invasive common buckthorn in Midwestern woodlands. New research demonstrates when and how they are best used.

Continue reading Goats can play a role in multi-pronged restoration of buckthorn-invaded woodlands →