Category Archives: Research

General research posts.

Research Pays Off Webinar Series: Determining Pavement Design Criteria for Recycled Aggregate Base and Large Stone Subbase

The National Road Research Alliance (NRRA) is hosting “Research Pays Off: Determining Pavement Design Criteria for Recycled Aggregate Base and Large Stone Subbase” on April 20 at 10 a.m. CST, presented by Bora Cetin, Ph.D., Michigan State University and Raul Velasquez, Ph.D., P.E., Minnesota Department of Transportation.

The NRRA’s monthly seminar highlights research topics that will make an impact on the work done here in the state of Minnesota and around the country.

Project Summary

Although recycled pavement materials have been used in roadway base layers for many years, a specific design method does not exist that describes how to build roadways with these materials. Many state Departments of Transportation (DOTs) assume recycled base materials behave similar to base layers built with conventional virgin aggregates (VA). There is a similar lack of an existing design methodology for pavement systems built with a large stone subbase (LSSB).

The proposed project has three main goals. The first goal of the project is to determine the field and laboratory performance of materials and test sections built with recycled aggregate bases (RAB) including recycled concrete aggregate (RCA), recycled asphalt pavement (RAP), and mixtures of these materials with VA. In addition, similar analyses will be conducted for the test sections built with 18 inches thick LSSB with different compaction methods (1-lift and 2-lift), and those 9 inches thick LSSB built with geogrids and geotextiles. To accomplish this goal, the research team will evaluate both the geomechanical and environmental properties of these pavement systems. It should be noted that the LSSB sections have only one type of aggregate base and the multiple recycled aggregate base sections do not have LSSB indicating that experiments for each different design methods are separate. The second goal of the project is to develop a method to estimate the stiffness and permeability of RAB and LSSB designs. This goal will be achieved by establishing correlations between common laboratory test data and both laboratory and field modulus and permeability values. The third goal is to prepare a pavement design and construction specification for roadways built with RAB and LSSB designs. This goal will be accomplished via a summary of the results of all tasks, taking into account the performance, cost benefits, and life cycle costs of these systems. The outcome of this research will optimize the use of recycled materials and LSSB designs, while maintaining pavement quality, resulting in cost savings and conservation of natural resources.

Visit the MnROAD website for webinar connection information.

Research Pays Off Webinar Series: FRC Jointless Roundabouts in Minnesota

The National Road Research Alliance (NRRA) is hosting “Research Pays Off: FRC Jointless Roundabouts in Minnesota” on March 16 at 10 a.m. CST, presented by Principal Investigator Peter Taylor, Ph.D., P.E., Iowa State and Technical Liaison Maria Masten, P.E., MnDOT.

The NRRA’s monthly seminar highlights research topics that will make an impact on the work done here in the state of Minnesota and around the country.

Project Summary

The use of roundabouts to improve safety and traffic flow in rural areas is growing rapidly in the U.S. Proper design details and construction methods are important to the long term performance of these facilities. Joint layout in roundabouts constructed with concrete pavement are especially challenging. To reduce the need for sophisticated joint layouts, some roundabouts are now be constructed without joints, utilizing structural fiber-reinforced concrete to bridge cracking that might occur. Fiber-reinforced concrete is also being used in thin concrete overlays to increase longevity and enhance joint load transfer capacity.

In 2018, Minnesota’s first jointless fiber-reinforced concrete (FRC) pavement roundabout was constructed near the city of Sleepy Eye. It is of interest to the NRRA Rigid Team members to understand the design, construction, and near-term performance of this roundabout. Also constructed in 2018 were two fiber-reinforced concrete whitetopping (bonded concrete overlay on asphalt) projects in southern Minnesota. These projects were unique in that early construction vehicle loading was applied to each project to encourage the deployment of transverse contraction joints. The NRRA Rigid Team members are interested in documenting the innovative steps performed during the early loading process.

The objectives of this study are twofold:

  1. Write a construction report and carryout a 3-year performance monitoring regime for the jointless FRC roundabout project
  2. Write a construction report for the two FRC whitetopping projects subjected to early loading.

Visit the MnROAD website for webinar connection information.

Team Receives NSF Grant to Study ‘Smart e-Scooters’

This article was originally published in Catalyst, November 2020.

Electric scooters let riders move quickly between the roadway and the sidewalk, but these sometimes-unpredictable travel patterns can pose risk for riders and the people around them. Making scooters smarter is the goal of a new U of M research project funded by the National Science Foundation (NSF). Under the $1.2 million Cyber-Physical Systems grant, a cross-disciplinary team will study smart tracking systems on scooters for ensuring safe and smooth interaction with other vehicles and pedestrians.

Continue reading Team Receives NSF Grant to Study ‘Smart e-Scooters’

Smartphone-Based Coaching for New Teen Drivers May Offer Long-Term Benefits

This article was originally published in Catalyst, August 2020.

More than five years ago, U of M researchers studied a group of new teen drivers to gauge the effects of real-time, in-vehicle coaching with their innovative Teen Driver Support System (TDSS) smartphone application. Now, a follow-up study offers new understanding about the system’s long-term effectiveness in reducing risky driving behavior.

Continue reading Smartphone-Based Coaching for New Teen Drivers May Offer Long-Term Benefits

Link Between Air Quality, Happiness Could Guide Infrastructure Decisions

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.

Continue reading Link Between Air Quality, Happiness Could Guide Infrastructure Decisions

MnDOT Announces COVID-19 Research Funding

The COVID-19 crisis has affected every aspect of the transportation systems, with state DOTs and local agencies at the forefront of responding to changes, while continuing to meet core missions of providing safe, efficient, and effective transportation systems. To proactively respond and inform future decision-making related to COVID-19’s impact on the transportation sector, MnDOT is investing in research to answer questions specific to the impact of the COVID crisis on Minnesota’s transportation system.

Continue reading MnDOT Announces COVID-19 Research Funding

Promoting Snow Fence Adoption in Minnesota

A new research study has shown that few landowners know about MnDOT’s snow fence program, its benefits to community safety and mobility, and incentives to install snow fences. Following community meetings and surveys in four regions of Minnesota, researchers identified promising promotional methods for the snow fence program, the constraints landowners face in adopting snow fences, and incentives and assistance to improve snow fence adoption. Project results will guide MnDOT’s efforts to expand the use of snow fences around the state

Continue reading Promoting Snow Fence Adoption in Minnesota