MnDOT Research

08/06/2026

Join us and the MN Local Road Research Board for this month's Research Radar: Turning Points: J-Turn and Roundabout Design, Economics, and Safety Outcomes.

Learn about how J-turns and roundabouts impact drivers, safety, and communities.

🔄 Research Radar: Turning Points: J-Turn and Roundabout Design, Economics, and Safety Outcomes
📅 Thursday, August 13 | ⏰ 10 a.m. - 11:15 a.m. CDT
✅ Free to attend | Registration Required

REGISTER HERE:

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08/05/2026

Researchers in a completed MnDOT-funded study evaluated a new low slump concrete mixture designed to reduce cracking on bridge decks and improve long-term performance. Study results show less cracking, improved durability, and a 33% reduction in cement use. The new mixture has been implemented at six field projects in Minnesota. Read more about the research and results below:

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 …

08/04/2026

Preventive sawing and sealing can help extend pavement life and reduce long-term maintenance costs. In a recently completed LRRB-funded study, researchers compared lower cost Binder B pavements with saw-and-seal techniques to higher cost Binder C treatments without sawing and sealing. Findings showed that saw-and-seal treatments are effective maintenance strategies with factors such as joint spacing, site conditions, mixture quality, and moisture susceptibility playing a major role in performance.

Asphalt pavements will inevitably begin cracking and require maintenance to preserve an adequate level of service. However, preemptively sawing and sealing roads at prescribed locations can reduce …

07/30/2026

Lightweight fill materials including tire-derived aggregate, foamed glass, and expanded shale could support more sustainable road construction. In a new LRRB-funded study, researchers will be evaluating environmental impacts, long-term performance, and behavior under Minnesota freeze-thaw and groundwater conditions. Findings will guide future construction decisions.

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, …

07/29/2026

Lower speed limits are becoming more common across Minnesota, but do they actually slow drivers down over time? In a new MnDOT and LRRB joint-funded study, researchers are studying speed trends 2-4 years after cities reduced limits, including how roadway design and added countermeasures impact results.

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…

07/09/2026

In a recently completed MnDOT and LRRB-funded study, researchers evaluated five gravel road stabilizers at 28 locations across Minnesota to identify options that reduce gravel loss and lower maintenance costs. Top-performing stabilizers and application methods reduced gravel loss by up to 82%. The results support informed decisions about maintaining gravel roads across Minnesota.

Gravel roads often experience significant deterioration that requires costly maintenance. To mitigate this deterioration, transportation agencies can apply chemical stabilizers to improve aggregate…

07/08/2026

A completed LRRB-funded study is helping engineers better understand and reduce surface tenting, a type of pavement distress caused by frost and moisture under the roadway. Researchers identified causes of tenting, evaluated pavement treatments and created new tools to help engineers choose the best maintenance options.

Transverse cracking and tenting are significant problems for asphalt pavements, especially in colder climates where the asphalt layer contracts during winter conditions. While the impacts of frost …

07/07/2026

Join us and the MN Local Road Research Board for this month's Research Radar: Smarter Stormwater & Stronger Foundations. Learn how new studies are helping to prepare Minnesota roads and water systems for heavier rain and changing weather.

Research Radar: Smarter Stormwater & Stronger Foundations
📅Thursday, July 16 | ⏰ 10 a.m. - 11:15 a.m. CDT
✅ Free to attend | Registration Required

REGISTER HERE: da289caf-0a4c-43a8-968f-8134a683aa27@eb14b046-24c4-4519-8f26-b89c2159828c" rel="ugc" target="_blank">https://events.gcc.teams.microsoft.com/event/da289caf-0a4c-43a8-968f-8134a683aa27@eb14b046-24c4-4519-8f26-b89c2159828c

07/02/2026

Concrete roundabouts are becoming more common across Minnesota and understanding their performance is essential for long-term safety and durability. A new MnDOT & LRRB-funded study will evaluate concrete roundabout designs statewide to identify pavement distress and the influence of design features such as joint spacing, dowel bar placement, and drainage features. The findings will help improve design practices and extend pavement life.

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 assumpt…

07/01/2026

Minnesota is home to over 30,000 stormwater ponds and historic wetlands that help keep phosphorus and other pollutants out of lakes and rivers. A completed LRRB-funded study examined the functions of stormwater treatment systems and identified the most effective strategies to remove phosphorus. Results showed that street-sweeping, chemical treatment, and mechanical aeration are among the strategies that help lower phosphorus levels.

Ponds and historic wetlands are essential for preventing excessive phosphorus from reaching downstream waters. These systems remove solids, nutrients, metals and hydrocarbons from stormwater runoff…