Appropriate deceleration on approaches to roundabouts is primarily accomplished through the use of applicable geometric design principles. However, traffic control devices (specifically signing and markings on approach) also serve a vital role in communicating to the approaching driver what speed profile should be anticipated. This report provides a resource for engineers to identify and select appropriate speed-reduction treatments for high-speed approaches to roundabouts. It includes a quick reference guide designed to help agencies determine which countermeasures are best used in different situations based on roadway type, location, and posted speed limits.

A best practices manual is now available to help local agencies improve the chip seal experience. While chip sealing is used to fill small cracks and generally improve pavement conditions, it can result in loose, small stones that can damage windshields and be tracked back to driveways, yards and homes. Applying an additional product—a fog seal—shortly after chip sealing may alleviate many of these concerns and extend pavement life. The goal of the project was to explore the cost-effectiveness of fog sealing over chip sealed roads, the ability of fog sealing to improve chip retention and fog sealing application methods. The research demonstrated that fog sealing over chip sealed roads can be a cost-effective solution leading to improved pavement conditions and public satisfaction.

Roadside turfgrass is necessary for stabilizing the roadway, preventing erosion and filtering stormwater runoff. Maintaining it can be challenging in Minnesota’s harsh climate. Deicing salt, snowplow damage, and summer heat can prevent vegetation from thriving. This research tested seed mixes and growing environments around Minnesota. It identified three general regions within the state that have distinct soil and weather characteristics. Cost-effective grass seed mixture recommendations designed to improve establishment of roadside vegetation, reduce soil erosion and improve aesthetics are provided for each region. A cost estimation tool developed to help local agencies in their roadside vegetation choices is also available. 

Rising construction costs and declining funding have created an estimated deficit of $17.7 billion for state roads over the next 20 years. The inability to maintain roads and bridges in good condition leads to shortened infrastructure life spans and higher future repair costs. As upkeep is postponed, the necessary road work grows and material costs increase, resulting in higher future maintenance costs. Research sponsored by the LRRB identifies factors that impact maintenance spending, examines how investment decisions are made and provides recommendations to help local governments close maintenance funding gaps. A new infographic that details these impacts is a tool that local agencies can use when communicating about the importance of maintaining an appropriate and stable level of maintenance funding.

This research looked at whether restored roadsides could provide safe habitats for declining pollinator populations. In a two-part study, researchers first used pollinator habitat maps to examine associations between the amount of nearby pollinator-friendly habitat and bumble bees. Then they examined the bumble bee and butterfly populations in 57 revegetated areas from 19 construction projects conducted over the past two decades. Extensive fieldwork and analysis of previous research led researchers to several general conclusions and recommended management strategies related to floral cover, native and nonnative plant species, and roadside vegetation maintenance.

Minnesota’s roads have been effectively treated for decades with chloride-based mixtures for anti-icing and deicing for winter driving. Salt, however, corrodes steel in vehicles and infrastructure. Additionally, chloride runoff harms the aquatic environment. This project, conducted by the University of Minnesota, is one of two projects (the other was conducted by Iowa State University) that explored the environmental impacts of an alternative to road salt—potassium acetate, which is effective on ice at lower temperatures. The shared goal was to investigate the fate, transport and degradation of potassium acetate used as a deicer or anti-icer, and its toxicity to biota.

NCE is conducting an agency survey as part of a Minnesota Local Road Research Board implementation project, Pavement Design Around Utilities – Best Practice. One project goal is to survey local agencies to identify current practices to adjust utility covers (specifically manholes, catch basins, and gate valve boxes) to finished grade as part of pavement rehabilitation, along with performance trends. This survey will take less than 15 minutes to complete, and your feedback will provide valuable information. 

Please respond by April 5, 2023. If you have any questions, please email Sarah Lopez. Thank you for your time to participate in this important study.

Have you or one of your co-workers recently built an innovative gadget or developed an improved way to do a job? Show off your creativity and help other agencies solve problems by submitting an entry to the Minnesota Build a Better Mousetrap Competition.

Your entry can be anything from the development of tools or gadgets to equipment modifications to processes that increase safety, improve efficiency, reduce costs, or improve the quality of transportation. The Minnesota competition is open to all local transportation agencies in the state. It is sponsored by the Minnesota Local Road Research Board and administered by Minnesota LTAP.

Submission deadline is May 15, 2023. To learn more and submit your entry, go to Build a Better Mousetrap Competition.

Check it out - Lake of the Woods County’s Minnesota Mousetrap award winner is one of five projects featured in the Federal Highway Administration's 2022 Build a Better Mousetrap Showcase video!

Stay up-to-date on the latest research, training, news and local transportation issues when you follow the Local Road Research Board on LinkedIn. 

Stay up to date with local transportation news by signing up for MnDOT Library City/County News Alerts. MnDOT library staff curate transportation news stories from around Minnesota to include in this monthly email alert. It also features a list of new materials available to you from the library including books, periodicals, reports, transportation association publications and more.

To sign up for alerts, go to the GovDelivery sign-up page for MnDOT Library alerts. You will be asked for your email and a data privacy consent. You can then sign up for City/County News Alerts as well as other alerts of interest. For additional assistance, go to Ask a Librarian.

It was great to connect with so many of you at the Minnesota County Engineers Association (MCEA) and City Engineers Association (CEAM) conferences in January. Susan Miller of SRF led our MCEA session, and Mike Marti and Renae Kuehl of SRF led our sessions at CEAM, sharing new resources available to local agencies and providing results of the sessions we held last fall to solicit new research ideas.

About 185 people attended our session at MCEA. Thank you to Bruce Hasbargen, Beltrami County and Jed Nordin, Hubbard County for co-presenting on Evaluation of SFDR Stabilizing Products, a project for which they served as technical liaison and TAP member respectively.

More than 500 people attended the LRRB overview during the general session at CEAM. We also hosted a session with 25 past and present LRRB and RIC members on the LRRB and how to get involved. Debra Heiser, engineering director, City of St. Louis Park, moderated both sessions.

Heiser, who served on the LRRB from 2006 to 2011 and on numerous technical advisory panels, says she thinks of the LRRB as the research and development department for city and county engineers. “It’s a resource that helps us stay on top of new research so that we can do our jobs better for our communities,” she said.