Tag Archives: feature

Materials and Construction, research

New Project: Tools to improve the durability of asphalt pavements

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This research focuses on improving the durability of asphalt pavements by examining emerging technologies, materials, and temperature‑control methods. Recent advancements—such as warm mix asphalt (WMA), polymer modifiers, bio‑binders, and surface treatments that reduce heat absorption—show strong potential for reducing asphalt aging and increasing resistance to thermal cracking. Environmental factors, including pavement shading from trees, have also demonstrated measurable effects on pavement temperature and long‑term performance.

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

Building on these developments, this project aims to conduct a comprehensive review of existing tools and evaluate two promising approaches in detail: WMA technology and updated asphalt binder specifications. Experimental testing will compare WMA with conventional mixtures, analyzing compaction behavior and low‑temperature cracking resistance using methods such as gyratory compaction and semi‑circular bend testing. Parallel testing of asphalt binders will assess new specification parameters to predict cracking performance more accurately under Minnesota’s climate conditions.

“We are always looking at increasing durability in our pavements,” said Michael Flaagan, county engineer for Pennington County, Minnesota. ”This research gives us additional choices in increasing performance with the potential for cost savings.”

The anticipated outcome is a set of practical guidelines for Minnesota agencies to integrate WMA and improved binder selection into current pavement practices. These strategies are expected to increase pavement lifespan, reduce maintenance costs, lower emissions, and support better decision‑making for agencies with limited budgets. By identifying and validating the most effective tools and materials, the project contributes to long‑term sustainability, cost efficiency, and improved resilience of the state’s asphalt pavement network.

The Objectives:

  1. Conduct a comprehensive literature review of current technologies, materials, and temperature‑control methods that improve asphalt pavement durability.
  2. Evaluate the compaction behavior and low‑temperature cracking resistance of warm mix asphalt (WMA) in comparison with conventional mixtures through laboratory testing.
  3. Assess newly proposed asphalt binder specification parameters using low‑temperature binder tests, including Bending Beam Rheometer (BBR) and Asphalt Binder Cracking Device (ABCD) methods, to better predict cracking performance.
  4. Develop preliminary guidelines for integrating WMA technologies and improved binder selection into Minnesota’s asphalt paving practices.

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

New Project: Utilizing hydrogen fuel technology for transportation fleets

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Minnesota Executive Order 19‑27 and State Statute 16C.135 set ambitious goals for MnDOT to reduce fleet fuel consumption and emissions by 2030 while prioritizing zero‑ and low‑emission vehicle purchases. Hydrogen fuel technology is being explored as a promising option to help meet these requirements without compromising operational needs. The research aims to assess existing and emerging hydrogen applications suitable for MnDOT’s medium‑ and heavy‑duty vehicles, compare hydrogen’s life‑cycle impacts with conventional fuels, and outline potential pathways for converting MnDOT’s fleet to hydrogen technologies.

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

“The use of hydrogen as a transportation fuel in Minnesota is in its infancy,” said Jed Falgren, P.E., MnDOT’s state maintenance engineer and office director for the Office of Maintenance. “While no commercial hydrogen fuel market exists in Minnesota today, this research will help us identify how we can best leverage the technology if/when it becomes available. Early identification of best practices can help us lower implementation costs in the future, and this continues our effort to identify fossil fuel alternatives that are safe and effective.”

The project anticipates several key benefits, including lower life‑cycle costs, significant reductions in greenhouse gas emissions, and insights into the safety and risks associated with hydrogen adoption. Expected outcomes include evaluating hydrogen‑powered fleet technologies from economic, environmental, and social perspectives, as well as identifying the strengths and limitations of different hydrogen systems. Together, these efforts could help position MnDOT as a leader in sustainable fleet management and support broader adoption of hydrogen infrastructure across Minnesota.

“The transportation strategies of today won’t get us to the Minnesota of tomorrow,” said Beth Croteau-Kallestad, sustainable transportation planning director in MnDOT’s Office of Sustainability and Public Health. “We’re excited to see MnDOT exploring fueling options that support health, reduce emissions and strengthen Minnesota’s future.”

The Objectives:

  1. To conduct a comprehensive survey of existing and emerging hydrogen fuel technologies suitable for MnDOT’s medium‑ and heavy‑duty vehicles.
  2. To evaluate the feasibility of these technologies for MnDOT’s operational needs.
  3. To perform a comparative life‑cycle assessment of conventional fuels versus hydrogen considering economic, environmental, and social impacts.
  4. To develop tentative plans for converting portions of the MnDOT fleet to hydrogen fuel systems.

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, research

New Project: Feasibility of LED Solar Street Lighting

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The need for this research stems from documented safety benefits associated with roadway lighting and the growing challenges in maintaining traditional, wired lighting systems. While rural locations often face high costs for delivering grid power to remote intersections, recent increases in wire theft has affected communities across Minnesota. These issues highlight the importance of exploring alternative, resilient lighting solutions that can improve safety without relying heavily on conventional electrical infrastructure.

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

The research process will assess the feasibility of solar‑powered LED roadway luminaires through a combination of laboratory testing, field evaluation, and cost‑benefit analysis. Key activities include analyzing battery performance under cold‑weather conditions, studying how lower illumination levels affect safety and energy use, and examining the practical integration of solar panels and batteries into existing streetlight design. A field implementation at selected sites, including potentially rural intersections or trail locations, will help validate performance and identify operational considerations such as durability, code compliance, and vandalism resistance.

The expected benefits of this work include reduced lifecycle costs, lower environmental impacts, and decreased operational and maintenance demands. Solar‑powered streetlights eliminate the need for grid‑based electricity, reduce wiring infrastructure vulnerable to theft, and offer long‑term savings over a planned service life. Environmental gains are anticipated through reduced energy consumption and lower CO2 emissions, while improved lighting reliability and appropriate illumination levels are expected to support nighttime safety and reduce crash risks statewide.

“This project will provide unbiased, objective research using equipment, methods, and people that would otherwise be unavailable to local government,” said Nick Peterson, city engineer for Saint Paul Public Works. “As a result, Minnesota cities and counties will learn effective strategies for implementing solar-powered street lighting in our cold climate.”

The Objectives:

  1. Test energy storage capacity of Lithium-ion battery under different temperatures. The battery energy storage capacity is a critical component in the feasibility of solar powered LED street lighting in cold northern climates.
  2. Explore the implications of running the streetlights at a lower brightness on power conservation and traffic safety. The balance between the energy demand for street lighting and the traffic safety is critical to an optimized solar powered LED streetlight that has a minimal solar panel and battery size and less effect on the existing streetlight infrastructure design.
  3. Conduct a comprehensive cost-benefit analysis considering material, labor, and maintenance costs for the installation and use of the solar-powered LED luminaire system, along with the benefits, such as the saved utility costs, the avoided costs of nighttime crashes, and the associated environmental benefits, such as the associated reduction of CO2 emissions.
  4. Provide MnDOT with guidelines and specifications on solar-powered LED streetlight implementation details.

Project Details:

  • Start Date: 07/16/2025
  • Estimated Completion Date: 05/31/2027
  • Funding: Local Road Research Board
  • Principal Investigator: Mijia Yang
  • Co-Principal Investigators: Xiangfa Wu and Yao Yu
  • Technical Liaison:  Nick Peterson

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: Evaluating and implementing ground penetrating radar for monitoring moisture fluctuations in in-service roads

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Moisture fluctuations within pavement foundations—driven by rainfall, freeze–thaw cycles, and groundwater changes—can significantly impact pavement performance, especially on Minnesota’s low volume roads. Traditional moisture measurement methods, such as in place sensors or falling weight deflectometer testing, tend to be costly, intrusive, slow, and offer limited spatial coverage. Ground penetrating radar (GPR), however, provides a faster, non-invasive, and more affordable way to assess subsurface moisture over large areas, making it particularly useful for local agencies with limited resources.

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

This research aims to advance the validation and practical use of GPR for evaluating pavement moisture in real‑world low‑volume road settings. The study includes conducting GPR surveys on test sections equipped with moisture sensors, comparing datasets, and assessing how effectively GPR can identify areas affected by drainage or moisture issues. To support broader implementation, the project also involves creating an automatic detection algorithm capable of identifying moisture variations in unbound pavement layers.

The algorithm will be refined into a user‑friendly software tool featuring modular code, a graphical interface, and documentation. Ultimately, the project will deliver implementation recommendations designed to strengthen decision‑support tools and technical guidelines, helping Minnesota’s transportation agencies more effectively monitor and manage pavement moisture conditions.

“For this research to reach its full potential, participation from local engineers and practitioners is essential,” said Eyoab Zegeye, research operation engineer at MnDOT’s Office of Materials and Road Research. “Based on our encouraging findings, the next step is to evaluate whether this approach could be implemented on real low‑volume roads and develop testing and reporting protocols that can be quickly adopted by local agencies. County and municipal staff have the closest understanding of their road networks, challenges, and resource limitations. Their involvement ensures that the tools developed are realistic, usable, and aligned with real‑world needs.”

The Objectives:

  1. Validate and implement GPR-based pavement moisture assessment methods on low-volume roads.
  2. Evaluate GPR’s ability to efficiently survey large pavement areas and monitor moisture conditions.
  3. Identify pavement sections potentially affected by drainage issues using GPR data.
  4. Conduct GPR surveys on low-volume road test sections equipped with in-situ moisture sensors and compare the results.
  5. Develop an automatic detection algorithm to evaluate moisture variation within unbound pavement layers.
  6. Validate the algorithm and implement it as software with modularized code, a graphical user interface, and a user manual.
  7. Produce implementation recommendations to enhance decision-support tools and technical guidelines for assessing moisture fluctuations in Minnesota’s low-volume roads.

Project Details:

  • Estimated Start Date: 7/16/2025
  • Estimated Completion Date: 6/30/2027
  • Funding: MnDOT and Local Road Research Board
  • Principal Investigator: Halil Ceylan
  • Co-Principal Investigators: Sunghwan Kim
  • Technical Liaison:  Eyoab Zegeye

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: Holistic design and selection criteria for unbound geomaterials used in pavement systems

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Unbound geomaterials used in roadway base layers strongly influence pavement durability, yet current practices in Minnesota often focus narrowly on gradation and index properties. This research seeks to fill that gap by examining mechanical behavior alongside hydraulic, water retention, and suction characteristics to better understand how these materials perform within real-world environmental and pavement systems.

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

Pavement base layers serve two essential purposes: providing mechanical support that prevents fatigue, settlement, and rutting, and enabling drainage that protects the structure from elevated pore pressures and freeze‑thaw damage. Although millions of tons of these materials are used annually, past studies rarely consider the full interaction between the base layer, surface conditions, and environmental factors.

The project’s primary goal is to develop a new holistic guideline for selecting unbound geomaterials and designing pavement foundations. By integrating both mechanistic and hydraulic considerations, the long‑term objective is to support a shift toward design approaches that enhance roadway performance while reducing maintenance needs and costs.

The Objectives:

This project aims to develop a new holistic unbound geomaterial selection and pavement foundation design guideline. This will be achieved through the completion of four primary objectives:

  1. Review of current roadway foundation design practices and guidelines of MnDOT and local counties and cities in Minnesota.
  2. Collection and analysis of existing data from the literature on the topic (including the extensive previous work of the research team).
  3. Developing a holistic design and material selection framework that explicitly takes material drainage characteristics, material mechanical characteristics, unsaturated soil mechanics properties, and prevailing environmental characteristics into account.
  4. Extensive laboratory and field testing to demonstrate and verify the new approach.
  5. Evaluating and modifying the pore suction resistance factors and seasonal multipliers used in MnPAVE.

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, research

Link Between Air Quality, Happiness Could Guide Infrastructure Decisions

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This article was originally published in Catalyst, August 2020.

By connecting measures of happiness to transportation, researchers are developing new metrics that can help cities prioritize infrastructure investments. In a new study, a research team that included Humphrey School of Public Affairs professor Yingling Fan found that air quality appears to be linked with a variety of emotional well-being (EWB) outcomes.

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Maintenance Operations

Guide for Converting Distressed Low-Volume Paved Roads to Unpaved Roads

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Working with an advisory panel of road managers from local agencies, researchers have developed a practitioner-ready guide for converting severely distressed low-volume paved roads to improved, easily maintained gravel roads. The guide includes decision-making tools and an online webinar for training.

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Materials and Construction

Guidance for Working With Potentially Acid-Generating Materials

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A new resource is available to help agencies greatly reduce the risk of disturbing potentially acid-generating (PAG) rock in places like northern Minnesota when conducting road projects. When exposed to air and water, PAG minerals can generate drainage that is hazardous to the environment. A MnDOT-sponsored research team developed a best practices manual that provides comprehensive steps to identify, mitigate and monitor PAG material during highway construction.  

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Environment

Innovative Research to Improve Bumble Bee Habitat

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Entomologists have developed an innovative method for surveying bumble bees alongside Minnesota roadways, the results of a new research study funded by the Minnesota Department of Transportation.

Research shows that MnDOT roadsides offer rich bumble bee habitats. The study offers information on surveying bee habitats and recommendations for improving habitats.

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Bridges and Structures

Putting Research Into Practice: New Tool Estimates Bridge Construction Time

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A new spreadsheet tool developed by the Minnesota Department of Transportation draws on historical data to help project engineers better estimate bridge construction time. The method allows users to project time-frames based on bridge design elements, work scheduling and other inputs, utilizing estimates from comparable projects in a 10-year database of bridge-building data.

Continue reading Putting Research Into Practice: New Tool Estimates Bridge Construction Time →