A new study sponsored by the Minnesota Local Road Research Board has identified 1,000 feet as an optimal sight distance for allowing drivers to make better crossing decisions at rural intersections. Researchers used a state-of the-art driving simulator to examine drivers’ ability to judge traffic speed and gaps between cars at unsignalized intersections with varying sight distances.Continue reading Optimal Sight Distances at Rural Intersections
The Minnesota Local Road Research Board has developed a new gravel road management tool — a simple, customizable spreadsheet for inventorying a gravel road system, tracking maintenance activity and expenditures, and budgeting and planning future needs.
A related user guide provides details about required inputs, gravel road evaluation protocols, and customization based on needs and available data.Continue reading New Spreadsheet Tool Helps Agencies Manage Gravel Road Systems
A new spreadsheet tool developed by the Minnesota Department of Transportation draws on historical data to help project engineers better estimate bridge construction time. The method allows users to project time-frames based on bridge design elements, work scheduling and other inputs, utilizing estimates from comparable projects in a 10-year database of bridge-building data.Continue reading Putting Research Into Practice: New Tool Estimates Bridge Construction Time
Researchers have refined an innovative, quick pothole repair method for both concrete and asphalt pavements without using asphalt or cement materials. Based on taconite, a plentiful Minnesota material, the repair mixture can be applied fairly quickly and shows promise as a cost-competitive, long-term solution for potholes.Continue reading Taconite-Based Mixture Shows Further Promise for Repairing Potholes
An evaluation of five maintenance paint coating systems on Minnesota steel bridges with localized corrosion found that each maintenance coating performed well, and, if corrosion is identified early and maintenance painting occurs, the service life of the paint coating system can be extended five years before repainting is required. Based on the test data, researchers recommended an update to MnDOT’s Bridge Maintenance Painting Manual that includes guidance on when to apply maintenance paint coatings and when to remove paint and recoat bridges.Continue reading Detecting Corrosion Early Extends Service Life of Bridge Paint Coating
The Minnesota Local Road Research Board has published a new guidebook to help local agencies get started on developing a consolidated asset management system. The guide addresses the particular needs of smaller groups to effectively and optimally manage their roadways, buildings, vehicles, equipment and other assets.Continue reading Asset Management Guide Addresses needs of Local Agencies
Positive offset left-turn lanes are one solution to improving left-turning motorists’ visibility of opposing through and right-turning traffic.
MnDOT is revising its Road Design Manual and seeks to incorporate more information, policies and design guidance regarding positive offset left-turn lanes.
Researchers from the University of Wisconsin’s Traffic Operations and Safety Laboratory reviewed safety performance data from research that examined left-turn offsets. They also consulted 23 state DOT road design guides to understand the extent of available guidance.Continue reading Design Standards for Unobstructed Sight Lines at Left-Turn Lanes
Researchers examined the practice of reducing the binder content of cold in-place asphalt recycling mixtures in the field on especially hot days to improve workability. Laboratory testing of mixtures at various temperatures and binder levels found the practice keeps mixtures workable, improves compaction and does not significantly diminish performance.Continue reading Evaluating the Performance of CIR Mixtures With Reduced Binder Content
Researchers developed sophisticated models for high-density asphalt pavement mixtures. After calibrating the model to experimental data available from 5 percent air void asphalt mixtures, the research team conducted tests on three Minnesota mixtures to further refine the model. A Phase II study will develop multiple high-density mix designs for Minnesota applications.Continue reading High-Density Asphalt Pavement Mixtures Viable with local Aggregates