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Snowplow operators are often tasked with clearing snow from roadways under challenging conditions. One such situation is low visibility due to falling or blowing snow that makes it difficult to navigate, stay centered in the lane, and identify upcoming hazards. To support snowplow operators working in these conditions, University of Minnesota researchers developed a snowplow driver-assist system that provides the operator with visual and auditory information that is suitable for low-visibility situations. A lane-guidance system uses high-accuracy Global Navigation Satellite System (GNSS) and maps of the roadway to provide information to drivers about their lateral positions. A forward-obstacle-detection system uses forward-facing radar to detect potential hazards in the roadway. The design of the system, and in particular its interface, is guided by extensive user testing to ensure the system is easy to understand, easy to use, and well liked among its users. The system was deployed in two phases over the 2020-2021 and 2021-2022 winter seasons. In total, nine systems were deployed on snowplows across Minnesota, four in the first winter season and an additional five in the second. Participating truck stations represented all eight MnDOT districts as well as Dakota County. Over the course of the deployment, additional user feedback was collected to identify system strengths and areas for improvement. The system was found to be a cost-effective addition to snowplows that increase driver safety, reduce plow downtime, and increase driver efficacy for plowing operations, thus providing support to operators working in demanding, low-visibility conditions.

The life of the various types of cutting edges for use on Motor Graders and Snowplows varies with the type of steel and its treatment by the manufacturer. This is an evaluation of the wear characteristics of five types of cutting edges, both Motor Patrol and Snowplow, used in the maintenance of gravel roads. Comparing the two sets of data (gravel and snow) excluding the Carbide edges, the Carbon is best on snowplows and second best but only slightly lower in durability than flame hardened on gravel blading. Gravel blading is about three times more severe than snowplowing on cutting edges other than Carbide Insert.

A Mn/DOT task force was formed to design an ergonomically correct snowplow truck cab which is cost effective and efficient. After brainstorming problems relating to snowplow cabs, four main issues were identified: visibility, controls, warning systems, and comfort. A survey was sent to Mn/DOT operators asking them to rate various factors on the four main issues. The survey also asked for additional comments on each of the factors. The overall ratings were lower than anticipated. A review of the comments led to the conclusion that lowered ratings were a result of the use of older trucks. Not all operators have exposure to or are aware of the improvements that have been implemented in newer trucks. This report includes the questionnaire, all responses, and recommendations for solving the problems which were identified.

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.

Accurate calibration of material application equipment is the primary means through which a transportation agency can avoid overapplication of salt and other winter maintenance materials to counter snow and ice on roadways. Methods of effective calibration for salt spreaders have been examined extensively and presented in many published reports and manuals. Manufacturers include comprehensive guides with their equipment. Thus, instruction and guidance is widely available. Clear Roads member agencies were interested in learning more about calibration accuracy of equipment over time: the practices and experiences of agencies that could help identify factors that may diminish calibration accuracy of equipment over weeks and months of use in extreme conditions. Through a literature search and a survey of Clear Roads member departments of transportation (DOTs) and others, this synthesis gathered information about the types of material application equipment that agencies use, schedules and methods of calibration, training protocols, respondents’ perceptions of the accuracy of equipment, and types and qualities of materials.

As a winter storm approaches, timing the activation and deactivation of winter maintenance operations has a significant impact on safety and budgeting. This synthesis report focuses on state practices in winter maintenance fleet activation for winter storms. A literature review and a survey of 25 Clear Roads states indicates that most agencies summon half or more of their workforce to come in before a storm arrives, if only just before. Meteorologists have become increasingly involved in winter maintenance programming, and a broad range of sophisticated systems, weather data and forecast sources are drawn upon in activation decisions, which are usually made at the district or regional level. Activation and deactivation procedures are data-heavy activities. Fleet activation practices seem equally informed by current and forecast data. Many states have specific thresholds (fixed numbers) for air temperature, pavement temperature, precipitation levels and other factors that trigger activation. Decisions about when to deactivate forces (send crews home) tend to be driven by a combination of fixed value thresholds and field observations. Current conditions are given more weight than forecasts, with the significant exception of precipitation forecasts. The increasing role of meteorology in winter maintenance activities suggests they may be becoming more data-driven.