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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.

The objective of this project was to develop materials to aid winter maintenance practitioners in making informed decisions on the use of road salts, specifically sodium chloride. To accomplish this, a detailed literature review was conducted, followed by a laboratory investigation that monitored ice formation and precipitation of salt at various concentrations and temperatures. Using the information collected through the previous tasks, a one-page fact sheet and educational video were developed to aid winter maintenance practitioners in how to use and apply information shown in salt phase diagrams. Results from the lab testing produced great images and video of ice and salt crystal formation in solution. Limited ice crystal data was collected and analyzed. Detailed ice crystal formation results could provide significant information to advance this topic. Images of ice crystals with bubbles, potentially filled with salt brine, indicate that the solid phase of ice crystals and salt crystals is not pure, implying that many phases can co-exist. This reinforces the concept that ice formed in the presence of salt brine is weaker than ice formed only in the presence of pure water. When measuring pavement friction following the application of salt brine at various concentrations, the results varied between pavement type, salt concentration, and friction measurement technique. There is value in further refining this, or another, performance test method to assess the influence of salt brine concentration on pavement friction.

Various costs and benefits are incurred while performing winter maintenance operations. However, a summary of these costs and benefits for different maintenance scenarios has not been compiled to date. This report summarizes past work that documented the quantified and non-quantified costs and benefits of three different winter maintenance strategies of interest; use of abrasives, salts and other chemicals in solid and liquid forms, and snow plows. Basic strategies were defined as plowing and use of abrasives, intermediate strategies were defined as the use of rock salt and salt brine (NaCl), and advanced strategies were defined as the use of corrosion inhibitors, inhibited salt brine, magnesium chloride, calcium chloride, and blended products. These approaches employ different components, both in terms of equipment as well as materials. Some components of the various strategies have better cost and benefit information available than others. This is particularly true of sanding/abrasives and salting. Other, more recently developed and employed approaches and materials have more limited cost and benefit information published. There are also a number of different environmental impacts associated with different components of each maintenance strategy. Using information gained from the literature review, surveys, and interviews summary benefit-cost matrices were developed for various winter maintenance strategies. Information and data gap analysis has aided in identification of areas for recommended research. This document is intended for use by transportation agencies, such as by maintenance supervisors, to aid in the decision making process in terms of the selection of winter maintenance strategies used to achieve a prescribed LOS.

This document is the final report for the Clear Roads project entitled Best Practices for the Prevention of Corrosion of Department of Transportation Equipment: A User’s Manual. The project team was led by researchers at the Western Transportation Institute at Montana State University (WTI) on behalf of Clear Roads, an ongoing pooled fund research effort focused on winter maintenance materials, equipment, and methods. Clear Roads research projects are managed and administered by the Minnesota Department of Transportation (MnDOT). Through this project, the research team developed a user-friendly manual that documents best practices for managing the risk of equipment corrosion, especially in the presence of chemical deicers. The audience for this manual includes operators, mechanics and garage-level supervisors. The manual defines the basic corrosion conditions, with a focus on the need for managing corrosion risks, common modes of corrosion failure, and corrosion-prone parts (priorities) on DOT equipment. This manual addresses design considerations and material selection for corrosion risk management. This manual also lists some commercial products that have been used by DOTs, and presents some successful experiences of DOTs, the US Navy and private companies. It also presents preventive maintenance strategies and tactics.

This manual was created as part of Clear Roads project CR13-04,"Best Practices for the Prevention of Corrosion of Department of Transportation Equipment: A User’s Manual," Published April 2015.

A manual on environmental best management practices used for snow and ice control was developed using information gain from a literature review, survey, and follow-up interviews. The document presents information on commonly used snow and ice control products and their potential impacts, and pathways into the environment. Following this information is presented on many aspects of snow and ice control operations from material handling and storage, application techniques and equipment, advanced technology for decision making, environmental management tools, pre-storm to mid-storm practices, post storm clean-up, and training. The manual summarizes common areas for improvement in snow and ice control practices to realize material and cost saving, while reducing impacts to the environment.

Agriculturally derived products, or agro-based products, and complex chloride mineral (CCM) based products are increasingly employed in snow and ice control operations, either used alone or more commonly as additives or blended with traditional chloride-based products such as rock salt (solid sodium chloride) and salt brine (liquid sodium chloride). Past studies and manufacturers have claimed that agro-based or CCM based products provide benefits such as freezing point depression, prolong performance on the road surface, the ability to utilize UV light as an aid to ice prevention, and various environmental benefits. However, the measurement of the effectiveness of such products has been limited. To further investigate the role CCM and agro-based products may have in deicing and corrosion protection, a literature review and national survey were conducted to identify potential products, how they are typically used, performance characteristics, and pros and cons. Ten products were selected for extensive laboratory testing which investigated the products ability to lowering the freezing point of water and improve the ice melting capacity, weaken the ice bond to pavement, improve the product longevity on the road surface, prevent ice formation or refreeze prevention, and assess the influence of absorbance of sunlight on product performance. Results of the laboratory testing and literature review were used to develop a best practices manual. This report documents the work completed for each task of this project, as well as provides a presentation of the major findings

This document is the final report for the Clear Roads project entitled Snow Removal Performance Metrics. The project team was led by researchers at Washington State University on behalf of Clear Roads, an ongoing pooled fund research effort focused on winter maintenance materials, equipment, and methods. Clear Roads research projects are managed and administered by the Minnesota Department of Transportation (MnDOT). Through this project, the research team conducted a comprehensive literature review on the use of performance measures by transportation agencies for winter highway maintenance activities. To identify the effective performance metrics for snow and ice maintenance operations, the team surveyed all possible snow and ice states to gather information about their use of performance measures. The survey results were tabulated and analyzed to identify commonalities and differences between agencies and to develop a matrix of performance measures. Relative costs associated with different metrics were also presented. Based on the literature review and survey results, recommendations were made regarding the performance measures that should be considered for further evaluation. Remaining knowledge gaps were also identified, and recommendations were made for cases where existing measures may be modified or new measures developed for evaluation in future research.

The objective of this project was to synthesize available information on non-chloride deicers to allow for a more comprehensive understanding by winter roadway maintenance professionals and allow for easy comparisons between products and with sodium chloride (as salt brine or rock salt). This was accomplished through a literature search that summarized research on non-chloride deicing products and identified 46 non-chloride deicing products, summarized research on applications of various heated pavement technologies, and summarized research on anti-icing and anti-bonding/water-repellent surface treatments. Two surveys of state and local transportation agencies and vendors and manufacturers of non-chloride deicing products were conducted, respectively. The survey of state and local transportation agencies identified non-chloride products used. An evaluation of the Clear Roads Qualified Products List (QPL) Specification Document and other standards and testing requirements was conducted, which suggests that a wealth of data is collected and available for review of non-chloride deicing products. A deeper evaluation of BOD, COD, nitrogen, phosphorus, cyanide, toxicity, and corrosion is provided, because these are of particular interest when considering non-chloride deicers. Subsequently, we developed educational primers, or two-page fact sheets, for key categories of non-chloride deicers – acetates, formates, glycols, and ag-based that serve as high-level overviews of information on non-chloride deicers that can be used to make informed decision when comparing products to sodium chloride as rock salt or salt brine. This work found non-chloride deicers to be a viable option in winter roadway maintenance operations and many transportation agencies across the country are successfully using these products.

Winter roadway operations, commonly known as snow/ice control operations, are one of the most critical functions of state, provincial and local transportation agencies in cold regions. These operations aim to provide safety and mobility by timely and effective application of materials and plowing. The most common materials used are salt (sodium chloride, solid and brine), magnesium chloride-based, and calcium chloride-based deicers, agro-based additives and blends, and abrasives, with the specific choice and application method and rate dependent on temperature, precipitation type, level of service goals, budget, and environmental sustainability. Best practices of material application are designed to apply the right type and amount of materials in the right place at the right time. A companion document to this report, the “Material Application Methodologies Guidebook,” synthesizes the use of materials, including application strategies, application rates, and application equipment. This report documents the literature review and agency interviews that were conducted to assemble the information for the Guidebook.