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The reliability of variables used in the calculation of storm severity indices or winter severity indices (SSIs/WSIs) was evaluated via an expansive literature review, an international survey, and two rounds of interviews with data and device managers. A Recommendations Guide was created to help agencies who want to improve upon or build anew an SSI/WSI; and included a thorough outline of reliable data, data sources, and SSI/WSI calculation methods. A spreadsheet tool was built that guides a user through the process of choosing variables and methods to address their predominant weather concerns.

The appendices for Clear Roads report CR18-03, Evaluation of SSI and WSI Variables," published December 2020.

This research brief was created as part of Clear Roads project 18-03, "Evaluation of SSI and WSI Variables," published December 2020.

Pre-wetting is an important tool in the toolbox of winter road maintenance (WRM) operations. This research project collected all available and recent information regarding pre-wetting practices through a comprehensive literature review, an online survey of WRM practitioners, interviews and case studies of nine selected agencies, and outreach to six identified equipment manufacturers/distributors. Through the synthesis of current and best practices, the project resulted in preliminary guidelines or recommendations, mainly based on trial-and-error and field experience, instead of systematic and scientific investigations. There have been many success stories of pre-wetting practice by transportation agencies in northern climates. The pre-wetted material stays on the surface longer, has less bounce and scatter, and resists traffic action. The case study agencies also reported that pre-wetting allowed them to achieve the specified level of service more quickly. A pre-wetting rate of 8–12 gal/ton is effective and 8–16 gal/ton is reasonable for increasing the speed and total ice melting capacity of solid salt and reducing the snow-pavement bond. Practitioners have reported that higher pre-wetting rates (than 10 gal/ton) can achieve better operational results, thus reducing the amount of granular salt needed. For trucks equipped with pumps to make salt slurry, a higher pre-wetting rate (30 to 50 gal/ton) can be achieved. A higher application rate should be used when there is a lower pavement temperature or a more severe snow event. All survey respondents reported the use of on-board systems to apply liquids to solids. Agencies may face initial resistance to pre-wetting from operations staff or other stakeholders, but training and information dissemination coupled with effective field trials will gradually mitigate concerns and build rapport. The project also identified knowledge gaps or research needs relevant to pre-wetting practice.

This research brief was created was part of Clear Roads project CR18-04, "Review and Summary of Pre-Wet Methods and Procedures," published May 2021.

The goal of this project was to aid winter maintenance managers in better understanding the performance and impacts of alternative methods for deicing, which may be non-chloride based deicers, blends of deicing products, or methods that reduce the number of applications or application rates of deicers. To achieve this, a literature review, survey, and follow-up interviews were used to develop case studies and recommendations on automatic vehicle location (AVL), blended liquid deicing products, direct liquid application (DLA), pre-wet, slurry, mechanical snow removal methods (ice breakers, squeegee plow blades, brooms, sweepers, segmented plow blades), methods to reduce chloride use, route optimization, salt alternatives, and using data to make informed decisions (severity indices (WSI, SSI, SWI), MDSS, and dashboards). Recommendations for implementation and successful use of each case study topic are provided, followed by recommendations on how to do a lot with a little, or how to identify and implement easy and low-cost improvements. This is followed by a section on making larger investments to find improvements. These sections provide examples, identify pros and cons, and review the challenges of going from being good at something to great. Key steps for implementation are identified, and training resources are provided. Research needs and gaps are identified related to alternative methods for deicing.

This research brief was created as part of Clear Roads project CR18-05, "Alternative Methods for Deicing," published May 2020.

Snowplow trucks operate in extreme conditions that take a toll on engines, wiring, controls, sensors, connectors, augers, conveyors, spinners and other parts exposed to extreme cold, wetness and corrosive materials. Consequently, winter road maintenance equipment may break down on the road. Road maintenance agencies have a range of protocols for dealing with equipment breakdown in the field, including troubleshooting via phone or radio, sending out a mechanic, or towing the truck back to the station. Most agencies would benefit from more training for operators and mechanics that would enable them to more effectively address problems that can result in snowplows breaking down on the road. This synthesis sought to identify the best practices agencies use to deal with breakdown of winter road maintenance equipment in the field; the types of experience sought by agencies in their operators and mechanics; and the maintenance and repair areas where operators and mechanics would benefit from additional focused training. A national survey of winter maintenance practitioners at state departments of transportation gathered information about best practices, common equipment failures, responses to failures, and training approaches for operators and mechanics. The results of a literature search supplemented the survey findings.

As part of this research project, a literature review, a survey of practice, field data collection, and an analysis of application rates was conducted. The literature review covered application rates, performance measures, chemical products, environmental impacts, corrosion, impacts on concrete and asphalt, agro-based products, and benefit-cost analyses. A survey of practice was conducted to gather agencies’ winter maintenance practices involving materials, predominant winter conditions, liquid application rates, experience, performance measures, and interest in serving as a study site. Agencies from different geographical regions of the United States were selected for field data collection to provide a wide range of winter conditions, road types, and resources. Data collected consisted of route information and field data in terms of weather, roadway conditions, materials, application rates, and performance measures. Seventeen agencies representing nine states submitted data from 31 routes resulting in field data for 167 storms. Ranges of application rates were identified according to pavement temperature, temperature trend, road surface condition, and materials used. Guidance was developed exclusively from field data and practitioner feedback. Guidance was developed for liquid applications, blends, and “Shake and Bake” for light snow conditions (<1 in/hr., <4” in 24 hrs.). Shake and Bake is a combination of liquid and solid applications. Application rate ranges are provided in tables by material, pavement temperature, temperature trend, and supporting information regarding field data (agencies and number of storms observed).

This research brief was created as part of Clear Roads project CR19-01, "Expanding Application Rate Guidance for Salt Brine Blends for Direct Liquid Application and Anti-icing," published December 2021,