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The traveling public increasingly relies on navigation systems, either as part of their vehicles or through their handheld phones or mobile devices. Currently there is not a consistent system, tool, or process being used by cities and counties in Minnesota to report road or bridge closures that local transportation agencies can use to display to the traveling public or provide to third-party mapping/navigation companies (e.g., Waze, TomTom, HERE Technologies, Google, Apple) so that these companies can display the information to the public. To move toward an approach for reporting road and bridge closures by local counties and cities, the Minnesota Local Road Research Board (LRRB) initiated this project, Using Apps to Notify the Public of Local Road and Bridge Closures. The objectives of this project were to identify and describe an approach the Minnesota LRRB could use to implement a user-friendly road closure reporting system and develop a guide on how local agencies could currently report closures to third-party mapping and navigation companies.

The Minnesota Speed Management Program (MSMP), a cooperative project between the Minnesota Department of Transportation and the Minnesota Department of Public Safety, was developed within the framework of the Minnesota Comprehensive Highway Safety Plan. The overall goal was to reduce the number of fatal and lifechanging crashes on Minnesota highways. The MSMP involved a speed limit adjustment—on 850 miles of Minnesota’s 55 mph highways the speed limit was increased to 60 mph. It involved increased speed enforcement—by State Patrol, county sheriffs, and local law enforcement—on selected highways. There were four waves of Enhanced Enforcement (one of six weeks, three of eight weeks) each followed by four weeks of Regular Enforcement. The MSMP involved extensive public education, organized by the Office of Traffic Safety, with approximately 10,000 public service messages presented on the radio. Two evaluation efforts were conducted. The University of Minnesota compared travel speed data and crash data obtained during the MSMP with historical data. Throughout the MSMP, there were decreases in the number of drivers traveling at least 10 mph above the speed limits—decreases of -28.7% on 2-Lane/2-Way Highways; -28.7% on 4-Lane Divided Highways; -42.9% on Rural Freeways; and -11.2% mph on Urban Freeways. The University’s evaluation also showed there were reductions in the numbers of fatal and life-changing crashes during the MSMP. MarketLine Research conducted the second evaluation, using telephone surveys, and found nine in ten drivers support the speed limit increase from 55 mph to 60 mph in both Metro and Greater Minnesota. The MSMP, in concert with other efforts that are part of the Minnesota Comprehensive Highway Safety Plan, resulted in reductions in the number of speeders on Minnesota Highways and reductions in the number of fatal and lifechanging crashes—making Minnesota’s roads safer.

This Technical Summary pertains to LRRB’s Research Implementation Committee’s product 2008RIC08, “Development of Scalable Technology to Enhance Transfer of Bridge Information,” released in October 2008. Note: because the final deliverable for this project was not a research paper, it is not stored in the MnDOT Digital Library.

This Technical Summary pertains to Report 2010-22, “Statistical Analysis of the Soil Chemical Survey Data,” published June 2010.

After visiting a variety of stop-controlled intersections in the Twin City metro area, the researchers developed, with the aid of a computer simulator, two innovative intersection designs to improve safety at unsignalized intersections on four-land, divided highways. These innovative designs offer a number of advantages; however, due to funding difficulties, the researchers were not able to test the effectiveness of the designs in a real world setting.

Many agencies use snowplow blades with carbide inserts to remove snow and ice from their roadways. While carbide inserts are effective at extending the service life of plow blades, there is variability in carbide quality and in the specifications used by each agency in their procurement. This project developed a set of standard specifications to improve this procurement process. Project tasks included a literature review and surveys of both winter maintenance agencies and snowplow blade manufacturers. Follow-up interviews and a site visit to a plant that manufactures these blades provided additional insight into the challenges and opportunities in creating a standard specification. The standard specifications developed cover the chemical composition and the metallurgical, mechanical and physical properties of the carbide inserts. In addition to these technical elements, the specifications include a general set of testing and inspection procedures that can be used to accept or reject a lot of carbide inserts. Separate specifications were developed for inserts with a trapezoid shape and bullnose shape. By putting these standard specifications into practice, winter road maintenance agencies can realize better performance in their plow blades and possible cost reductions as manufacturers can streamline their manufacturing and inventory processes to more efficiently prepare blades to a single set of specifications.

This research brief was produced as part of Clear Roads project CR17-02, "Standard Specifications for Plow Blades with Carbide Inserts," published April 2020.

Revisions to the appendices of Clear Roads project CR17-02, "Specifications to Standardize Plow Blades with Carbide Inserts."

Mounting video cameras on winter maintenance vehicles can assist with operational decisions and enhance situational awareness for operators. To help agencies maximize the benefits of these systems, this project conducted a state-of-the-practice literature review, survey and interviews to identify types, uses and best practices for on-vehicle camera systems. Among the agencies surveyed, the most common use was a rear-view device, but cameras are also used to monitor material spreaders, underbody plows and tow plows to verify operation and effectiveness. Several best practices emerged from the research and interview process. These included: • Cameras should be carefully positioned so they do not interfere with driver sight lines or getting into or out of the vehicle. • Cameras should have washer systems and heated lenses, as accumulation of dirt or snow can rapidly degrade image quality. • Cameras are often sold as packages with washer systems. Research shows that low-cost cameras can be used with washer systems, even if they are not initially packaged with them. • In-cab displays should be carefully positioned and have driver-adjustable brightness to avoid distracting reflections on windshields. • In general, it is not recommended to integrate the video from forward-facing cameras into in-cab displays. • Transmitting live video from vehicles is currently poorly supported by cellular networks, particularly outside urban areas, and is not generally recommended. • Involving operators during the planning and installation of cameras has been shown to increase effectiveness and acceptance of the system.

This research brief was produced as part of Clear Roads project CR17-03, "Aftermarket Cameras in Winter Maintenance Vehicles," published June 2021.