Two county roads provided a testing ground for three combinations of aggregate bases and asphalt binders. Results from more than two decades of research and monitoring of pavement test sections validated previous conclusions. A larger gradation aggregate base showed superior performance over the pavement life cycle when compared with the standard aggregate base. Additionally, sections constructed without transverse joints to allow natural thermal cracking outperformed sections with sawn and sealed joints.
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Effectively Alerting the Public About Local Road Closures
Navigation apps can be valuable timesavers for drivers in Minnesota. To maximize their use, these apps need traffic information that is timely and accurate. While state highway closures are reported effectively, reporting road closures on local roads and highways is inconsistent. This project aimed to improve local road closure reporting by exploring the development of a streamlined reporting system and creating guidance for reporting local road closures to third-party navigation apps.
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New Project: Improving and Developing Pavement Design Inputs and Performance Functions for Cold Recycled Pavement Layers
Local agencies in Minnesota use cold recycling technologies for flexible pavement rehabilitation because of their economic and environmental benefits. The three main methods are cold in-place recycling (CIR), cold central plant recycling (CCPR), and stabilized full-depth reclamation (SFDR).
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New Project: Development of a System to Report School Bus Stop Arm Violations
When a motorist ignores an extended school bus stop arm, it creates a direct and serious risk to children boarding and exiting a school bus. Capturing information about such incidents is a critical step in better understanding why they occur and how they can be prevented.
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New Project: Evaluation of Static and Dynamic No Right Turn on Red Signs at Traffic Signals
Making signalized intersections safer for pedestrians can be achieved by reducing points of conflict between pedestrians and vehicles. One source of conflict occurs when a vehicle makes a right turn on red (RTOR) onto a street in which pedestrians are crossing. During this turn, the driver must cross the path of pedestrians while at the same time searching for gaps in conflicting vehicle flow.
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Drainage 101: Understanding and Managing Drainage Issues
Increased regulation and rising levels of precipitation have made stormwater management a more routine and time-consuming issue than in previous decades. A new resource provides guidance and best practices that will help city and county engineers, local officials and private property owners navigate the complex, often public-facing issues related to recurring drainage problems and stormwater management.
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Adapting Asphalt Mixtures for Tougher Rural Roads
Seasonal and daily temperature variations, freeze-thaw cycles and other environmental factors lead to pavement distress on low-volume rural roads. Modifying asphalt mixtures could improve pavement resistance to these environmentally driven distresses. A comparison of the mechanical properties and performances of selected asphalt mixtures identified a mixture and method that hold considerable promise for improving performance and longevity on low-volume roads.
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MnDOT and the Local Road Research Board Award Funding to New Research
MnDOT and the Minnesota Local Road Research Board have funded 21 new research projects and are seeking Technical Advisory Panel members to help guide the research. This year’s RFP received over 83 proposals from qualified universities across the country. To receive updates on any of the funded projects, select “subscribe” on the project webpage.
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Evaluating and Communicating the Benefits of Transportation Research
Assessing the return on investment in transportation research is crucial to ensuring program goals are met, knowledge and technology are shared broadly, and future investigations are prioritized. A recent effort leveraged existing MnDOT and LRRB tools and processes to evaluate and communicate the value of innovation and research. A new benefit monitoring and communication framework, which can be tailored to individual projects, allows agencies to reassess a project and its benefits throughout the research life cycle.
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Impact of Urban Speed Limit Changes on Driving Speeds
Speed limits are a popular safety measure used in urban areas. A new analysis that monitored driving speeds before and after posted changes to speed limits reveals lower speed limits may not, at least initially, cause drivers to slow down.
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Crossroads 