All posts by mndotresearch

Urban Rapid Transit Reduces Traffic on Nearby Roads

Light rail transit and bus rapid transit in the Twin Cities provide urban residents with fast, safe and reliable transportation. These transitways have the potential to attract more riders and further reduce automobile traffic, relieving the growth of congestion on nearby roads as people decide to be transitway passengers rather than motorists. 

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Strategies for Recruiting and Retaining Minnesota’s Transportation Workforce

Across the transportation industry, public and private employers are experiencing workforce shortages and an uncertain future. As older employees retire and younger workers fill their roles, organizations must naturally adjust to accommodate their changing workforce. In the transportation industry, shifting demographics have also brought new attitudes regarding technical jobs. The result is that fewer engineers and other highly skilled professionals are entering the field, and keeping those who do is becoming increasingly difficult. To address this changing landscape, transportation agencies of all sizes must be prepared to meet the challenges ahead or risk falling behind.

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Evaluating the Impact of J-Band on Pavement Service Life and Crack Resistance

Potholes and other pavement failures in asphalt typically occur at the seams between lanes, where the mixture loses density during compaction because the edges are not confined like they would be with cement concrete forms. Researchers found that spraying J-Band, a void-reducing asphalt membrane (VRAM), in a band along longitudinal joints before asphalt layers are applied increased bond strength, lowered permeability and air void levels, and improved crack resistance.

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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.

Local Guidance for Bicycle Facility Design

A quick reference guide is now available to help local agency planners and designers select the best bicycling facilities for their system. This guide walks local agencies through the selection and design process, and directs users to specific places within design manuals for details on facility questions.

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Smartphone App Gives Crossing Guidance to the Visually Impaired

In a recent research project, MnDOT sought to validate a smartphone app designed to guide pedestrians who are blind or visually impaired through signalized and unsignalized intersections. The project succeeded in showing the app’s effectiveness in tests at six intersections in Stillwater, Minnesota.

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Low-Volume Road Runoff Analyses Suggest Optimal Treatments

Assisted by many county agency staff, researchers collected and analyzed runoff from low-volume rural roads over two years to determine how their contaminants compared to those of high-volume roadways. Results documented that runoff from low-volume roads has a lower contaminant concentration and that ditches and swales can be used to effectively treat rural road runoff.

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