Sustainable Winter Road Operations

The first and only comprehensive guide to best practices in winter road operations

Winter maintenance operations are essential to ensure the safety, mobility, and productivity of transportation systems, especially in cold-weather climates, and responsible agencies are continually challenged to provide a high level of service in a fiscally and environmentally responsible manner.  

Sustainable Winter Road Operations bridges the knowledge gaps, providing the first up-to-date, authoritative, single-source overview and guide to best practices in winter road operations that considers the triple bottom line of sustainability.

With contributions from experts in the field from around the world, this book takes a holistic approach to the subject. The authors address the many negative impacts on regional economies and the environment of poorly planned and inadequate winter road operations, and they make a strong case for the myriad benefits of environmentally sustainable concepts and practices. Best practice applications of materials, processes, equipment, and associated technologies and how they can improve the effectiveness and efficiency of winter operations, optimize materials usage, and minimize cost, corrosion, and environmental impacts are all covered in depth.

• Provides the first up-to-date, authoritative and comprehensive overview of best practices in sustainable winter road operations currently in use around the world
• Covers materials, processes, equipment, and associated technologies for sustainable winter road operations  
• Brings together contributions by an international all-star team of experts with extensive experience in designing, implementing, and managing sustainable winter road operations
• Designed to bring professionals involved in transportation and highway maintenance and control up to speed with current best practice

Sustainable Winter Road Operations is essential reading for maintenance professionals dealing with snow and ice control operations on highways, motorways and local roads. It is a valuable source of information and guidance for decision makers, researchers, and engineers in transportation engineering involved in transportation and highway maintenance. And it is an ideal textbook for advanced-level courses in transportation engineering.

• Language: English
• Publisher: Wiley
• Release date: Mar 27, 2018
• ISBN: 9781119185154

Book preview

1

Introduction to Sustainable Winter Road Maintenance

Xianming Shi¹ and Liping Fu²

¹ Department of Civil & Environmental Engineering, Washington State University, Pullman, WA, 99164‐2910

² Department of Civil & Environmental Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada

1.1 Introduction

1.1.1 Motivation for This Book

This book is motivated by the opportunities made possible by leveraging recent advances and significant knowledge accumulated in various aspects related to winter road maintenance (WRM), such as weather forecasting, sensor and equipment technologies, operational practices and materials, and performance measurement, to achieve sustainable winter operations. These opportunities enable new perspectives on and holistic approaches to achieving sustainability of WRM operations by minimizing physical and chemical impacts, economic costs, and societal vulnerabilities and risks of winter storms, and maximizing the synergies across multiple modes and jurisdictions.

Investing in WRM operations is essential and beneficial to the public and the economy. In many northerly countries and regions, WRM operations are essential to ensure the safety, mobility and productivity of transportation systems. The U.S. economy cannot afford the cost of shutting down the transportation system, such as highways and airports, during wintery weather. According to the U.S. Federal Highway Administration (FHWA), over 70 percent of the nation’s roads are located in snowy regions, which receive more than five inches average snowfall annually … Nearly 70 percent of the U.S. population lives in these snowy regions (Figure 1.1). Transportation agencies are under increasing pressure to provide a high level of service (LOS) and to improve safety and mobility in a fiscally and environmentally responsible manner. It is therefore desirable to be able to make full use of best practices in the application of materials, strategies, equipment and other technologies. Such best practices are expected to improve the effectiveness and efficiency of winter operations, to optimize material usage, and to reduce associated annual spending and corrosion and environmental impacts. As described in Nixon et al. (2012), WRM operations include six interrelated components and processes where improvements for sustainability can be made, as illustrated in Figure 1.2.

Map of the United States displaying dark shaded areas affected by snow and ice surrounded with dots.

Figure 1.1 U.S. areas affected by snow and ice

(Adapted from: FHWA 2016).

Key components and processes in winter transportation operations, displaying a box labeled Staffing and Training with boxes inside linked by arrows labeled Strategic Operations, Tactical Operations, etc.

Figure 1.2 Key components and processes in winter transportation operations

(Adapted from: Nixon et al. 2012).

WRM operations can greatly contribute to a safe and efficient transportation system and thus facilitate economic development by reducing logistics costs of firms and individuals. The U.S. alone spends $2.3 billion annually to keep highways clear of snow and ice, with another $5 billion estimated damage to the transportation infrastructure and natural environment (FHWA 2005). WRM operations have lasting economic, social and environmental impacts. They offer such benefits to the public and society as: fewer accidents, improved mobility, reduced travel costs, reduced fuel usage, sustained economic productivity, continued emergency services, etc. (Figure 1.3). An example of a winter storm hindering the U.S. economy occurred in 1996 when a blizzard shut down much of the northeastern U.S. for four days. The loss in production and in sales was estimated to be approximately $10 billion and $7 billion, respectively, without taking account of accidents, injuries or other associated costs (Salt Institute, 1999). A recent study for the National Research Council estimated the quantifiable benefits of winter highway maintenance by the Minnesota Department of Transportation (DOT) to be about $220 million per winter season, even without considering the risk of highway closures in the absence of winter operations (Ye et al. 2013).

A circle divided into 3 portions with photos, back view of a truck with snowy mountain at the background (top left), back view of cars on the road (top right), and back view of an ambulance on the road (bottom).

Figure 1.3 WRM operations are vital to economy and society.

Sustainability in WRM operations has become a growing consideration over the past decade. Since a consensus has been reached that the principles of sustainability should guide all transportation design and operations, a variety of efforts have been conducted to follow this recognition. The U.S. FHWA has developed a practical, web‐based collection of best practices that would assist state Departments of Transportation (DOTs) with integrating sustainability into their transportation system practices. Winter maintenance has emerged as a critical area for transportation sustainability (Nixon 2012; Nixon and Mark 2012; Nixon et al. 2012; Shi et al. 2013).

1.1.2 The Need for This Book

Winter road maintenance has always been an integral part of transportation operations for agencies that must deal with the impacts of adverse winter weather. Significant advances have been made in the various aspects of WRM operations, such as deicing/anti‐icing materials, maintenance practices, equipment, and road weather and surface‐condition monitoring. Most of these developments have been motivated by the need to provide a high level of service (LOS) and improve safety and mobility in a sustainable manner. However, currently there are no professional societies or scientific journals or textbooks dedicated solely to sustainable winter road operations and the key information is scattered across a variety of disciplines and in various forms of publications. As more agencies are exploring the impacts of WRM operations, including voluntary and regulatory controls to reduce their impacts, the development of a comprehensive book is timely to consolidate best practices and recent advances in sustainable WRM operations and to help reduce the cost and environmental footprint associated with WRM operations.

In this context, this book aims to bridge a significant knowledge gap and to address the pressing need for such a book for both education and workforce development. It will be the first book to provide a holistic perspective on the benefits and potential negative impacts of WRM operations while promoting environmental sustainability concepts and practices. This book will serve as essential reading for maintenance professionals in charge of snow and ice control operations on highways, local roads, etc. It will also serve as a textbook for senior elective or graduate‐level courses, with outstanding potential for online education. Webinars and training modules could be developed using this book as the blueprint.

1.2 How the Chapters and Topics Are Organized

Following this introductory chapter, the rest of the book tackles the multiple dimensions of sustainable WRM operations. The individual chapters, while covering different topics related to WRM, are interrelated, with some serving as input to the others, as schematically illustrated in Figure 1.4. Chapter 2 provides a framework for assessing the life‐cycle sustainability of salt application in winter maintenance operations. The framework integrates the triple bottom line of sustainability, i.e., economics, environmental stewardship and social progress in accounting for the direct and indirect costs, benefits and impacts over the entire life cycle of road salt. Chapter 3 provides a historical perspective detailing the important developments and evolutions in materials, maintenance strategies, and equipment over the past three decades in advancing sustainable WRM operations. Chapter 4 discusses the societal and user expectations of WRM operations, as well as how agencies establish their LOS standards.

A row of 3 trapezoids illustrating the relationship between individual book chapters, each with titles on top portion followed with bulleted lists for the chapters.

Figure 1.4 Relationship between individual book chapters.

Chapter 5 provides an overview on how road weather services can greatly contribute to sustainable WRM operations. Chapter 6 discusses the fundamentals of plowing, anti‐icing, deicing, and sanding operations, laying out the foundation for developing ways to improve the performance and sustainability of various maintenance treatments. Chapter 7 and Chapter 8 provide an overview of the methodologies that can be applied to understanding and quantifying the effects of winter weather and maintenance operations on road safety and mobility, respectively. Chapter 9 discusses the economic benefits of WRM operations and examines how they can be used in cost‐benefit analysis of maintenance policies, programs and technology investment. Chapter 10 provides an overview of the environmental risks that some commonly used deicing/anti‐icing materials may pose. Chapter 11 and Chapter 12 discuss the risks of WRM operations to the transportation infrastructure and motor vehicles, respectively, as well as the corresponding best practices to manage such risks.

Chapter 13 focuses on planning and management strategies for achieving sustainable WRM, such as network partitioning or districting, fleet sizing and mixing, siting of RWIS stations, and salt management. Chapter 14 discusses sustainability practices in the domain of source control tactics, including innovative snow fences for drift control, anti‐icing, deicing and pre‐wetting practices, maintenance decision support systems (MDSS), fixed automated spray technology (FAST), equipment maintenance and calibration, advanced snowplows and spreaders, and material and snow storage. Chapter 15 discusses reactive approaches to reducing the environmental impacts of snow and ice control materials after their application on pavement. Chapter 16 focuses on the decision‐making process for selecting the appropriate types of innovative equipment for WRM. Chapter 17 discusses the search for greener materials for WRM operations, with a focus on the development and evaluation of deicers. Chapter 18 provides an overview of pavement innovations that can reduce the need for chemicals or abrasives for WRM operations.

Chapter 19 describes the benefit of performance measurement in responsible and sustainable winter maintenance management, an overview of common performance measures, and how to overcome the challenges associated with analyzing winter operations performance. Chapter 20 presents a review of current snow and ice control methods and a guide for selecting an optimal application rate for specific weather, treatment and LOS requirements. Chapter 21 concludes the book with a look into the future in terms of the main challenges and opportunities and future research and development in sustainable WRM operations.

References

FHWA (2005). How Do Weather Events Impact Roads. Federal Highway Administration. Available at http://ops.fhwa.dot.gov/Weather/q1_roadimpact.htm, accessed 3 May 2005.

FHWA (2016). Snow and Ice. Federal Highway Administration. Available at http://ops.fhwa.dot.gov/Weather/weather_events/snow_ice.htm, accessed 1 Nov. 2016.

Nixon, W.A. (2012). Measuring sustainability in winter operations. Proceedings of the 2012 Transportation Research Board Annual Meeting, Washington, D.C.

Nixon, W.A., Mark, D.R. (2012). Sustainable winter maintenance and a 22‐in. blizzard: Case study. Proceedings of the International Conference on Winter Maintenance and Surface Transportation Weather, Coralville, Iowa, April 30 to May 3, 2012: Transportation Research E‐Circular E‐C162.

Nixon, W.A., Nelson, R., DeVries, R.M., Smithson, L. (2012). Sustainability in winter maintenance operations: A checklist. In Transportation Research Board 91st Annual Meeting, Washington, D.C. (No. 12–3485).

Salt Institute (1999). Billions at Risk during Snow Emergencies: Snowfighting Investment Pays Big Dividends. Alexandria, VA.

Shi, X., Veneziano, D., Xie, N., Gong, J. (2013). Use of chloride‐based ice control products for sustainable winter maintenance: A balanced perspective. Cold Regions Science and Technology, 86, 104–112.

Ye, Z., Veneziano, D., Shi, X. (2013). Estimating statewide benefits of winter maintenance operations. Transportation Research Record: Journal of the Transportation Research Board, (2329), 17–23.

2

A Framework for Life‐Cycle Sustainability Assessment of Road Salt Used in Winter Maintenance Operations

Na Cui,¹ Ning Xie,² and Xianming Shi³

¹ School of Civil Engineering and Architecture, University of Jinan, Jinan, Shandong, China 250022

² Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, Jinan, Shandong, China 250022

³ Department of Civil & Environmental Engineering, Washington State University, Pullman, WA 99164–2910

2.1 Introduction

One of the basic requirements for successful implementation of a winter road maintenance (WRM) program is the appropriate selection of deicers (Shi et al., 2013). Traditionally, nominal cost and effectiveness are the major criteria used by roadway professionals when making such selection. However, there is growing concern over the negative impacts of such chemicals on the natural environment (Levelton Consultants, 2007; Corsi et al., 2010; Fay and Shi, 2012), transportation infrastructure (Pan et al., 2008; Shi et al., 2010; Xie et al., 2016), and motor vehicles (Shi et al., 2009; Dean et al., 2012). To tackle these risks, some endeavors have been made to find alternatives to regular road salt, e.g., agro‐based and complex chlorides/minerals‐based products (Hossain et al., 2015; Muthumani and Shi, 2016). These have triggered the need to adopt sustainability principles for WRM operations, so as to ensure that any cost savings of winter maintenance practices would not be at the expense of deteriorated infrastructure, impaired environment, or jeopardized traveler safety.

The principles of sustainability generally put emphasis on the triple bottom line: economy, environment and society, and these have yet to be applied to WRM operations. Over the past decade, addressing sustainability in WRM operations has attracted more attention (Nixon, 2012). To assess the life‐cycle sustainability of chloride‐based deicers for WRM operations, it is not sufficient to estimate only the economic savings from enhanced winter roadway safety and mobility; the indirect costs and benefits associated with infrastructure degradation, vehicle corrosion, etc. must also be investigated. Furthermore, efforts should be made to quantify the life‐cycle footprint of each deicer for the natural environment and for society. It should be cautioned that many of the items regarding costs (or benefits), environmental impacts, and social impacts can be intangible, hard to quantify, and inherently stochastic, making it difficult to conduct a reliable life‐cycle sustainability assessment (LCSA).

Since a consensus has been reached that the principles of sustainability should guide all transportation designs and operations, a variety of relevant efforts have been made towards adopting them in WRM operations. An example is the development of a practical, web‐based collection of best practices by the U.S. Federal Highway Administration (FHWA), aimed to assist state departments of transportation (DOTs) with integrating sustainability into their practices in managing the transportation system. A FHWA tool, INVEST (Infrastructure Voluntary Evaluation Sustainability Tool), provides a segment on winter maintenance, including a road weather information system (RWIS), a materials management plan, and a maintenance decision support system (MDSS), and shows the implementation of standards of practice for snow and ice control (Shi et al., 2013). These endeavors have been useful in promoting sustainability in WRM operations, but do not provide any framework to enable reliable quantification of life‐cycle sustainability of deicers or other WRM practices.

The multiple dimensions of deicer selection demand an integrated sustainability assessment framework, which is currently non‐existent in the published literature. Yet this framework is much needed by agencies so that they can appropriately assess the related social–economic costs and benefits of a deicer and comprehensively account for its environmental impacts, and thus make more informed decisions based on comparisons of different deicer products and improve their operations (Fitch et al., 2013). For instance, depending on the design and manufacturing technique of products used for snow and ice control, the mining, production, distribution, storage, and application of these compounds unavoidably contribute to the environmental footprint of WRM operations. The negative impacts of deicers on vehicles and infrastructure also induce secondary environmental impacts. As such, it is important to consider the entire life cycle of deicers, from mining/extraction, processing, storage, distribution, roadway application to eventual fate and transport in the environment, or recycling. These considerations should be examined with a life‐cycle approach and a balanced perspective among all relevant stakeholders.

A LCSA framework would help produce a full picture of the impacts of each step in the use of deicers and thus facilitate more balanced decisions. As such, this chapter anatomizes the LCSA framework of road salt (the most commonly used deicer for anti‐icing, deicing and pre‐wetting practices), through analyses based on the triple bottom line. This reflects the current state of thinking on the structure of the LCSA framework for road salt, including concepts, complexities and caveats, and considerations in each of the three branches of LCSA (economic, environmental, and social aspects). While this framework is the first step in the right direction, we envision that it will be improved and enriched by continued research and may serve as a template for the LCSA of other WRM products, technologies, and practices.

2.2 Concepts of LCSA

LCSA represents a new philosophy that has been widely discussed in recent years (Zamagni, 2012). Based on the definition in the context of sustainable development, the triple bottom line or the three pillars mode forms the basis of expression for LCSA in its measurement. This can be overly simplified as a linear equation (2.1) as follows.

(2.1)

where LCC, LCA, and SLCA denote life‐cycle costing, environmental life‐cycle assessment, and societal life‐cycle assessment, respectively. They respond to the economic, environmental, and societal aspects of sustainability assessment, respectively, and jointly constitute the systematic structure of LCSA (Zamagni, 2012; Kloepffer, 2008).

LCC works to capture the economic effects of an industrial product or activity throughout its life‐cycle stages. Usually it starts from calculating the direct cost, from extraction of resources, to production and usage of the product, to the cost management of product reuse, recycling, and disposal. Benefit accrued during any of the life‐cycle stages can be considered a negative cost. Woodward defined the life‐cycle cost of an industrial product or activity as: the sum of all funds expended in support of the item from its conception and fabrication through its operation to the end of its useful life (Woodward, 1997). Harvey (1976) proposed a general LCC procedure, summarized in Figure 2.1, in which the step Define the cost elements of interest entails the estimation of the direct cost that occurs during the service life of an industrial product or activity; Define the cost structure to be used entails the grouping of costs to identify potential trade‐offs in the optimization of LCC; Establish the cost‐estimating relationships entails a mathematical expression that estimates the cost of an industrial product or activity as a function of different variables; and Establish the method of LCC formulation entails the process to finalize an appropriate approach to evaluate the life‐cycle cost of an industrial product or activity.

A row of 5 boxes connected by arrows labeled from define the cost element of interest to define the cost structure to be used, establish the cost estimating relationship, establish the method of LCC formulation, and LCC.

Figure 2.1 Harvey’s LCC procedure (Harvey, 1976).

LCA was developed as an analytical tool to assess the environmental impacts of an industrial product or activity. The International Standards Organization (ISO) initiated a global standardization process for LCA, including the development of four standards (goal and scope definition, inventory analysis, impact assessment, and interpretation), as well as a definition and basic requirements, as shown in Figure 2.2. In the ISO 14040 standard, LCA was defined as the compilation and evaluation of the inputs, outputs and potential environmental impacts of a product system throughout its life cycle (Guinee et al., 2002). The typical environmental impact categories include: energy consumption; resource use; emissions (related to climate change, ozone layer depletion, acidification, eutrophication, etc.); toxicity; water; and waste.

A box with 4 ovals inside linked by arrows labeled goal and scope definition, inventory analysis, impact assessment, and interpretation, with an oval outside the box linked by arrows labeled direct application.

Figure 2.2 The LCA framework based on the ISO 14040 standard.

SLCA focuses on the social impacts of an industrial product or activity, specifically on the societal aspect of life‐cycle sustainability (Jorgenen et al., 2010). SLCA differs from its precursor, Social Impact Assessment (SIA). Even though SIA also aims to examine the social impacts of industrial products or activities, impacts across a whole life cycle are generally not included in its analysis. In contrast, SLCA can be defined as an aggregation of all phases of SIA in a product’s life cycle (Fan et al., 2015). With a research focus on the effects of activities on humans, SLCA faces a major challenge in how to quantify the social impacts of the particular system under assessment. Dreyer et al. (2006) presented an SLCA approach to standardize and quantify the social impacts as specific numbers by using scorecards, and later further improved it with more details and specifics for social issues and location. However, the method requires site‐specific data that may not be readily accessible. Jorgensen et al. (2012) considered the most important part of SLCA to be the obtaining of available data and recommended conducting the SLCA with generic data, such as those from national censuses or public surveys. In 2006, a series of socioeconomic indicators were introduced for the application of SLCA, including human rights, labor practices, decent working conditions, and product responsibilities. These factors are directly affiliated with a stakeholder of the corresponding product (Grießhammer et al., 2006). The indicators affiliated with the stakeholders in the life cycle of a product or activity tend to provide the assessment of midpoint (e.g., worker, consumer, local community, society, and value chain actors shown in Figure 2.3).

5 Simplified stakeholder categories in the production system, illustrated by boxes labeled from stakeholders to worker, consumer, local community, society, and value chain actors, each branching further.

Figure 2.3 Five simplified stakeholder categories in the production system.

Source: Fan et al., 2015. Reproduced with permission of Springer.

In light of the working procedures and impacts of using road salt in WRM operations, it can be found that the three branches mentioned above are all embodied in WRM activities and are interrelated. The next section thus will provide a brief discussion on the complexities and caveats in the LCSA of road salt, aimed at helping agencies achieve the goal of life‐cycle sustainability assessment from economic, environmental, and social aspects.

2.3 Complexities and Caveats in the LCSA of Road Salt

Currently there are considerable challenges in the quantification or estimation of the performance and impact of road salt in a given region and comprehensive LCSA of road salt is needed for informed decision‐making. Where appropriate, necessary assumptions usually have to be made in order to bridge the knowledge gaps that currently exist in certain aspects related to the economic, environmental, and social impacts of road salt application. The potential sources of such complexities in the LCSA study of road salt (or other snow and ice control products) may include, but are not limited to, the issues discussed as follows.

First, there are indirect implications in terms of the environmental footprints, costs, or benefits of road salt, which can be considered ripple effects. This raises the need to define the boundary and time scale of the analysis domain and select the appropriate temporal and spatial resolution for the LCSA study. For instance, the application of road salt on winter pavement can induce higher risk of premature failure of concrete bridge decks, asphalt pavements, and motor vehicles, leading to the need for more frequent rehabilitation or repair activities and related traffic congestion. This, in turn, would induce a larger environmental footprint in terms of energy consumption, resource use, emissions, water pollution, etc., as well as indirect or secondary costs. To facilitate the LCSA, it is necessary to define the boundary of the analysis so as to focus on the major considerations. In addition, chlorides are known to be conservative in the environment. The application of road salt in many scenarios may pose little risk to the adjacent water bodies due to low acute concentrations observed, but pose significant risk to the water bodies over the longer term (e.g., accumulation over decades). It is thus necessary to define the time scale of the analysis so as to facilitate the impact assessment.

Second, the costs, performances, and impacts of road salt application can be regionalized, localized, or site‐specific, whereas the current LCSA typically adopts general values which overly simplify them. For example, numerous studies have reported environmental risks of deicers, indicating that the actual effects are highly site‐specific and depend on the density of road networks; climatic, soil, hydrological, and vegetation characteristics of the site; type and amount of product applied, etc. (Fay and Shi, 2012). Thus there is always a lack of reliable data for quantitative studies. Even though available data could be adopted either from laboratory and field testing or from historical records and literature review, they may not be applicable for individual site conditions.

Third, many of the processes underlying the costs, performances, and impacts of road salt application are stochastic in nature, whereas current approaches for assessment are typically deterministic. For instance, the effect of salt‐laden stormwater runoff from roads on the adjacent river or stream is partly affected by the flow rate and precipitation of the current and subsequent time periods. The fate and transport of sodium chloride and other additives in the road salt can be very complicated, in light of the inherently site‐specific and stochastic nature of the underlying processes and their interactions. In other words, there is no universal or deterministic model that can be employed to reliably predict the level of the impacts posed by the road salt on the receiving roadside soil, water bodies, aquatic biota, and vegetation, and on human health.

Finally, the fate and transport of road salt in the environment and how salt deteriorates the natural environment and assets are poorly understood, let alone the quantification of costs and risks. There remains a lack of effective correlation between the data obtained from current laboratory methods employed to assess the environmental impacts of deicers (e.g., aquatic toxicity of road salt) and their actual field impacts.

These complexities and caveats in the LCSA study of road salt illustrate the challenges of addressing such sustainability assessment. As such, the next section presents a preliminary LCSA framework of road salt, which serves as a first step in the direction of decomposing the complexities, summarizing the key factors, and establishing a framework for further improvements.

2.4 A Preliminary LCSA Framework of Road Salt

This section provides a detailed anatomy of the LCC, LCA, and SLCA branches in the integrated LCSA framework for the road salt used in WRM operations. We place the focus on factors, components, and actions that should be considered in each branch, as well as on the relationships between these concepts in the LCSA system.

2.4.1 LCC Framework

The LCC framework of road salt considers the following factors and components: capital and annual costs, disposal cost, life of assets, and discount rate, for the time period under analysis. The costs may include those to the roadway agency and those to the roadway users. Once the expenditure stream is developed as a function of time, the net present value or annualized value of the road salt for snow and ice control can be calculated. The LCC can take either a deterministic or probabilistic approach, the latter of which is a more realistic representation of the actual situation. This is because most of the input factors for LCC feature some level of uncertainty and would be better characterized by a statistical distribution than a single value.

Generally the capital and annual costs include the costs of mining/manufacturing and storage (e.g., raw material extraction, land use, anti‐caking treatment, ventilation, and packaging), transportation (e.g., from factory to DOT salt storage shed), implementation (e.g., application of road salt for anti‐icing, deicing or pre‐wetting practice), training (e.g., for the staff managing, handling and applying the road salt), equipment, and labor. Note that the benefits accrued from the application of road salt in terms of improved traveler safety and mobility, reduced travel cost and fuel savings (Ye et al., 2013; Usman et al., 2012; Shahdah and Fu, 2010) can be considered as negative costs under the implementation category.

Disposal cost usually does not occur until the end of the service life of the assets. For the LCC of road salt, the disposal cost of the salt itself is typically negligible since the salt is typically not recovered from the environment once it is applied onto the pavement for snow and ice control. Instead, the disposal cost of motor vehicles and transportation infrastructure may be considered in the LCC framework, and so it is the life of these assets which is affected by their exposure to the road salt. The disposal cost may include the costs of demolishing, transportation (to the disposal site), landfill, and labor, and could be minimized with best practices in recycling repurposing, or reuse of the materials.

For LCC, the dollar values of all the cost and benefit components occurring in future years should be expressed in terms of current year dollars, i.e., present value. For analysis of costs and benefits directly or indirectly related to road salt, the discount rate could be considered within the range of 3% to over 20%, depending on the market needs and supplies, organizations, and technologies.

2.4.2 LCA Framework

Drawing upon the published literature, environmental LCA can be iteratively described by the following four categories: goal and scope definition, life‐cycle inventory analysis, impact assessment, and interpretation.

Goal and Scope

For road salt, the goal of its LCA is to account for the negative impacts its life cycle may pose to the natural environment, including surface water, groundwater, air, soil, vegetation, wildlife, etc. As such, the results of LCA can be used to aid best practices by agencies to minimize negative environmental footprints and to address environmental justice and ecological issues.

In terms of scope or domain of analysis, the LCA aims to consider both the direct impacts of road salt on the receiving environment and the indirect environmental impacts (e.g., those induced by the premature failure of corroded equipment or transportation infrastructure). The environmental benefits derived from the use of road salt will be considered as well, including those from the avoidance of traffic accidents and delays, translated to reduced emissions and fuel consumptions (Min, 2015). It is cautioned that the scope can vary greatly as a function of time duration, geographic location, local priorities of environmental stewardship, technological context of salt application and infrastructure preservation, and possibly political and cultural constraints. As such, it is necessary to clearly define the scope of LCA before comparing different alternatives or different studies against each other.

Life‐Cycle Inventory (LCI)

LCI is a process employed to define the inputs and outputs of an industrial product or activity interacting with the environment, and to collect data regarding the resultant environmental burden (ISO, 1998). The inputs of road salt in the LCI analysis mainly include the raw materials and energy consumed during the course of mining, manufacturing, storage, transportation, implementation, and disposal. The raw materials may include not only the sodium chloride mineral and other additives in the road salt for WRM, but also the materials for preservation or rehabilitation of transportation infrastructure and the salt remover, anticorrosion coating, or corrosion inhibitor for equipment preservation. The outputs may include greenhouse gas emissions and other airborne pollutants, solid wastes (e.g., deteriorated vehicle parts, asphalt pavement, and concrete bridge deck), traffic noise (due to salt‐deteriorated ridability of pavement surface), and liquid effluents (e.g., salt‐laden stormwater runoff) discharged into the receiving environment.

Life‐Cycle Impact Assessment (LCIA)

LCIA works to translate LCI results into potential environmental impacts, and the major concerns include human health, natural environment, natural resources, and manmade environment (Hauschild et al., 2005). The widely accepted four steps of LCIA include: the selection of impact categories and classification, characterization, normalization, and valuation (ISO, 2000). For road salt, the main environmental impact categories include: acute and chronic toxicity of sodium chloride and other additives to aquatic species and human beings; air/soil/vegetation/water pollution due to application of road salt; air/soil/vegetation/water and noise pollution due to increased preservation or rehabilitation activities of transportation infrastructure; chronic deterioration of wildlife habitat; greenhouse gas emissions (a.k.a., global warming potential); energy consumption; and solid waste. During the characterization step, the environmental impact in each category is quantified into scores or equivalent values (e.g., converting the greenhouse gas emissions into kg CO2 equivalents). The quantification of the environmental impacts can be highly variable and stochastic, depending on the geographical location, salt application process, and characteristics of the receiving environment. During the normalization step, the magnitude of these impact scores is normalized to the same scale that is applied to all the impact categories. During the valuation step, the relative importance of impact scores is evaluated by ranking or weighting factors.

Interpretation

The results of interpretation can help agencies understand the potential negative effects of road salt on the receiving environment and make more environmentally conscious decisions in light of the local priorities and constraints. It can also provide support to optimize the previous three categories in an iterative process to revise the goal and scope, LCI, and LCIA until a final decision can be made, as shown in Figure 2.2.

2.4.3 SLCA Framework

The SLCA framework of road salt considers both the positive and negative impacts of using road salt for WRM operations. On the positive side, there are societal benefits of road salt in terms of avoided traffic accidents and improved convenience due to the improved level of service on winter pavement. While difficult to monetize, the improved convenience may be realized in the form of continued community services, reduced response time to emergencies, reduced traveler discomfort, and reduced wage loss associated with absence from work. Other societal benefits may include increased worker opportunities, technology development, etc. listed in Figure 2.3.

On the negative side, there are societal implications of using road salt, in terms of increased risk to human health; inconvenience associated with increased inspection and rehabilitation of motor vehicles, equipment, and roadway infrastructure; and possible increase in social inequality. First, there have been exceedances of the EPA water standard for chloride reportedly attributable to the use of road salt (Trowbridge et al., 2010). The conservative nature of sodium and chloride ions in the natural environment makes it difficult to remove them. Their concentration peaks during runoff or accumulation over the long term, along with their possible role in leaching other metals out of soil, can pose a health risk to human beings. Second, for assets exposed to road salt, their serviceability and durability are compromised, which necessitates more frequent inspection and rehabilitation (Li et al., 2013; Suraneni et al, 2016). Finally, underinvested and underserved communities are typically more vulnerable to the environmental and infrastructure impacts posed by the use of road salt, due to lack of resources. As such, there may be social inequality induced by the use of road salt.

2.4.4 Other Considerations

Life of Assets

The service life of motor vehicles and transportation infrastructure under the exposure of road salt can be estimated in terms of their physical life, technological life, economic life, and social and legal life (Ferry and Flanagan, 1991). It is worth noting that the resulting LCC, LCA, and SLCA with a longer‐service‐life prediction (e.g., over 50 years) is considerably different from a short‐term prediction (e.g., less than 10 years). As such, decisions on the service life of these assets should be included in the LCSA framework (Stone, 1980).

Uncertainties and Sensitivity Analysis

Uncertainty is an inevitable factor to consider when implementing the LCSA of road salt (or other WRM products, technologies, or practices). For instance, uncertainties are inherent in the estimation of discount rate in future years, in the dynamics of supply vs. demand of road salt, in deicer usage and frequency (as a function of policy, equipment innovations, climatic conditions, etc.), in corrosion and environmental risks (as a function of the fate and transport of road salt and secondary pollutants), in the safety and mobility benefits achieved from the application of road salt, and so on. In addition, the social impacts of applying road salt can vary greatly by location, cultural, and societal heritage, regulatory practice, technologies, worker environment, etc. In the SLCA, most of the indicators are not easily identified or measured. Furthermore, in light of the limited data available from actual records or statistical analysis, necessary assumptions are often made during the analysis, which adds to the level of uncertainties.

To improve the reliability of the analysis results, it is desirable to conduct sensitivity analysis of LCSA, i.e., by examining how the outcome of LCSA would change by varying each input factor used in the LCSA within a given range or a given statistical distribution.

Information and Feedback

The efficacy of LCSA analysis of road salt largely depends on the information collection and necessary feedback across the entire life cycle of road salt. Currently, there is a significant gap in the data needed to enable a quantitative or semi‐quantitative LCSA of road salt. The data on costs (and benefits), environmental impacts, and social impacts need to be collected over a reasonably long duration (e.g., 40 years), from a diverse yet representative array of scenarios, and in a consistent and ideally standardized format. This is an area where collaborative efforts are much needed between roadway agencies and other stakeholder groups.

2.4.5 The Relationships of LCC, LCA, and SLCA in the LCSA

LCSA is a combination of LCC, LCA, and SLCA with some linear or nonlinear and static or dynamic features. It integrates the impacts of all three pillars of sustainability through the analysis of LCC, LCA, and SLCA, respectively, and provides a reasonable approach to evaluating industrial products or activities from a life‐cycle perspective.

Previous research suggested that The combined impacts, positive and negative, of the sets of measures as a whole, are likely to be more than the simple sum of the impacts of their constituent measures because of synergistic effects (Lee and Kirkpatrik, 2001). Therefore, the LCSA of road salt has to be considered as a function of LCC, LCA, and SLCA rather than a linear sum of these three branches. Specifically, their mutual effects and interdependencies have become an important factor that determines the assessment results (as shown in Figure 2.4). The expression of their relationships in the original linear equation (2.1) can be rewritten as:

(2.2)

where each of the functions of LCC, LCA, and SLCA can be expressed as a function of the other two branches, as shown below:

(2.3)

A circle labeled LCSA surrounded with 3 ellipses labeled LCC, LCA, and SLCA, linked by double-headed arrows.

Figure 2.4 The interactions between LCC, LCA, SLCA and LCSA.

Figure 2.5 illustrates the interactions between the LCC, LCA, and SLCA of road salt, which must be considered comprehensively in the LCSA process. For instance, vehicle corrosion and road infrastructure deterioration due to road salt can pose negative impacts, mainly to economics and the natural environment. The soil pollution, vegetation deterioration, decreased water and air quality, and compromised wildlife habitat and human health due to road salt can pose negative impacts, mainly to the natural environment and human society. The safety and efficiency of the transportation system during winter weather can be enhanced by the appropriate use of road salt, which then poses positive impacts in all three domains of sustainability: economic, societal and environmental. In other words, it is risky to conduct the LCC of road salt without conducting LCA and SLCA, since this type of isolated analysis may result in misinformed decisions which ignore environmental and social impacts that cannot be readily monetized. Similarly, it is not a holistic or sustainable approach to conduct the LCA or SLCA of road salt without accounting for the economic impacts.

The interactions considered in the LCSA process, displaying circles linked by arrows labeled from Transportation to Manufacturing, Storage, Application of Road Salt, Impacts, and then branching further.

Figure 2.5 The interactions considered in the LCSA of road salt.

Figure 2.6 provides a fishbone diagram for the preliminary LCSA framework of road salt used in WRM operations, which can be adopted to enable more holistic and balanced decisions. Currently there are significant knowledge gaps in quantifying many of the cost, benefit, or impact items in each branch, which remain to be addressed in future research. Case studies and practitioner surveys are strongly recommended to help address some of these knowledge gaps. Furthermore, the interactions between the LCC, LCA, and SLCA can further complicate the quantitative analysis under this LCSA framework. Nonetheless, we anticipate that the LCSA framework developed for road salt could be extended to other types of WRM products, technologies, and practices.

LCSA fishbone diagram of road salt used in WRM operations, with boxes labeled Other Considerations, Direct Costs, Social & Environment Impacts, etc. and an ellipse labeled Life-Cycle Sustainability Assessment.

Figure 2.6 The LCSA fishbone diagram of road salt used in WRM operations.

2.5 Conclusions

Given the growing interest in assessing the life‐cycle sustainability of WRM operations, this chapter presents an initial exploration of the development of an integrated LCSA framework for the road salt widely used in WRM programs. The LCSA framework aims to help produce a full picture of the impacts of each step in the use of road salt. The chapter started with a description of the key concepts, i.e., LCC, LCA, and SLCA, that respond to the economic, environmental, and societal aspects of sustainability assessment, respectively. This was followed by a discussion of complexities and caveats, including the indirect implications of using road salt, the site‐specific nature of costs, performances, and impacts of road salt application, the stochastic nature of underlying processes, and the poor understanding in many aspects. Subsequently, this chapter provided a detailed anatomy of LCC, LCA, and SLCA branches in the integrated LCSA framework for the road salt used in WRM operations. In addition, the interactions between LCC, LCA, and SLCA, and how to quantitatively characterize the indicators in each branch, were recognized as knowledge gaps to be addressed in future research.

Acknowledgements

This research was supported by the Center for Environmentally Sustainable Transportation in Cold Climates (CESTiCC), the National Natural Science Foundation of China through Project 71403069, and the Postdoctoral Science Foundation of China through Grants 2014M551261 and 2015T80361.

Questions

1 How would the life‐cycle sustainability assessment procedures of winter road maintenance operations improve the existing cost evaluation?

2 What are some of the considerable challenges when it comes to the LCSA of road salt?

3 What is the main difference between the life‐cycle costing and the life‐cycle sustainability assessment of road salt in winter road maintenance operations?

4 What are the relationships between LCC, LCA, and SLCA in the LCSA?

References

Corsi, S.R., Graczyk, D.J., Geis, S.W., Booth, N.L., Richards, K.D. (2010). A fresh look at road salt: Aquatic toxicity and water‐quality impacts on local, regional, and national scales. Environmental Science Technology, 44, 7376–7382.

Dean, W.P., Sanford, B.J., Wright, M.R., Evans, J.L. (2012). Influence of deicers on the corrosion and fatigue behavior of 4140 steel. Journal of Materials Engineering and Performance, 21, 2340–2344.

Dreyer, L.C., Hauschild, M.Z., Schierbeck, J. (2006). A framework for social life cycle impact assessment. International Journal of Life Cycle Assessment, 11, 88–97.

Fan, Y., Wu, R., Chen, J., Apul, D. (2015). A review of social life cycle assessment methodologies. In Social Life Cycle Assessment. Springer, Singapore.

Fay, L., Shi, X. (2012). Environmental impacts of chemicals for snow and ice control: State of the knowledge. Water, Air, and Soil Pollution, 223, 2751–2770.

Ferry, D.J.O., Flanagan, R. (1991). Life Cycle Costing—A Radical Approach. Construction Industry Research and Information Association, London.

Fitch, G.M., Smith, J.A., Clarens, A.F. (2013). Environmental life‐cycle assessment of winter maintenance treatments for roadways. Journal of Transportation Engineering, 139, 138–146.

Grießhammer, R., Benoît, C., Dreyer, L.C., Flysjö, A., Manhart, A., Mazijn, B., … and Weidema, B.P. (2006). Feasibility Study: Integration of Social Aspects into LCA. Öko‐Institut, Freiburg.

Guinee, J.B., Gorée M., Heijungs R., Huppes, G., Kleijn R., de Koning, A., van Oers, L., Wegener Sleeswijk, A., Suh, S., Udo de Haes, H.A., de Bruijn, H., van Duin, R., Huijbregts, M.A.J. (2002). Handbook on Life Cycle Assessment: Operational Guide to the ISO Standards. Book Series: Eco‐Efficiency in Industry and Science: Vol. 7. Kluwer Academic Publishers, Dordrecht, May 2002.

Harvey, G. (1976). Life‐cycle costing: A review of the technique. Management Accounting, October, 343–347.

Hauschild, M., Jeswiet, J., Alting, L. (2005). From life cycle assessment to sustainable production: Status and perspectives. CIRP Annals‐Manufacturing Technology, 54, 1–21.

Hossain, S.K., Fu, L., Lake, R. (2015). Field evaluation of the performance of alternative deicers for winter maintenance of transportation facilities. Canadian Journal of Civil Engineering, 42(7), 437–448.

ISO (1998). Environmental Management: Life Cycle Assessment: Goal and Scope Definition and Inventory Analysis. International Organization for Standardization (ISO) 14041, Geneva, Switzerland.

ISO (2000). Environmental Management: Life Cycle Assessment: Life Cycle Impact Assessment. International Organization for Standardization (ISO) 14042, Geneva, Switzerland.

Jorgenen, A., Finkbeiner, M., Jorgensen, M., Hauschild, M. (2010). Defining the baseline in social life cycle assessment. International Journal of Life Cycle Assessment, 15, 376–384.

Jorgensen, A., Dreyer, L., Wangel, A. (2012). Addressing the effect of social life cycle assessments. International Journal of Life Cycle Assessment, 17, 828–839.

Kloepffer, W. (2008). Life cycle sustainability assessment of products. International Journal of Life Cycle Assessment, 13, 89–95.

Lee, N., Kirkpatrik, C. (2001) Methodologies for sustainability impact assessments of proposals for new trade agreements. Journal of Environmental Assessment Policy Management, 3, 395–412.

Levelton Consultants (2007). Guidelines for the Selection of Snow and Ice Control Materials to Mitigate Environmental Impacts. NCHRP Report, 577. National Research Council, Washington, D.C.

Li, Y., Fang, Y., Seeley, N., Jungwirth, S., Jackson, E., Shi, X. (2013). Corrosion by chloride deicers on highway maintenance equipment: Renewed perspective and laboratory investigation. Transportation Research Record: Journal of the Transportation Research Board, (2361), 106–113.

Min, J. (2015). Quantifying the Effects of Winter Weather and Road Maintenance on Emissions and Fuel Consumptions. Master’s thesis, University of Waterloo, Ontario, Canada.

Muthumani, A., Shi, X. (2016). Effectiveness of liquid agricultural by‐products and solid complex chlorides for snow and ice control. Journal of Cold Regions Engineering. (Accepted).

Nixon, W.A. (2012). Measuring sustainability in winter operations. Transportation Research Board Annual Meeting, Washington, D.C.

Pan, T., He, X., Shi, X. (2008). Laboratory investigation of acetate‐based deicing/anti‐icing agents deteriorating airfield asphalt concrete. Asphalt Paving Technology—Proceedings, 77, 773.

Shahdah, U., Fu, L. (2010). Quantifying the mobility benefits of winter road maintenance—A simulation based analysis. In TRB 89th Annual Meeting Compendium of Papers DVD, Washington, D.C.

Shi, X., Fay, L., Yang, Z., Nguyen, T.A., Liu, Y. (2009). Corrosion of deicers to metals in transportation infrastructure: Introduction and recent developments. Corrosion Reviews, 27, 23–52.

Shi, X., Fay, L., Peterson, M.M., Yang, Z. (2010). Freeze–thaw damage and chemical change of a portland cement concrete in the presence of diluted deicers. Materials and Structures, 43(7), 933–946.

Shi, X., Veneziano, D., Xie, N., Gong, J. (2013). Use of chloride‐based ice control products for sustainable winter maintenance: A balanced perspective. Cold Regions Science and Technology, 86, 104–112.

Stone, P.A. (1980). Building Design Evaluation Cost in Use. University Printing House, Cambridge, U.K.

Suraneni, P., Salgado, N., Carolan, H., Li, C., Azad, V., Isgor, B., … and Weiss, J. (2016). Mitigation of deicer damage in concrete pavements caused by calcium oxychloride formation–use of ground lightweight aggregates. In Proc Int RILEM Conf on Materials, Systems and Structures in Civil Engineering, Denmark.

Trowbridge, P.R., Kahl, J.S., Sassan, D.A., Heath, D.L., Walsh, E.M. (2010). Relating road salt to exceedances of the water quality standard for chloride in New Hampshire streams. Environmental Science & Technology, 44(13), 4903–4909.

Usman, T., Fu, L., Miranda‐Moreno, L.F. (2012). A disaggregate model for quantifying the safety effects of winter road maintenance activities at an operational level. Accident Analysis & Prevention, 48, 368–378.

Woodward, D. (1997). Life cycle costing—theory, information acquisition and application. International Journal of Project Management, 15, 335–344.

Xie, N., Shi, X., Zhang, Y. (2016). Impacts of potassium acetate and sodium‐chloride deicers on concrete. Journal of Materials in Civil Engineering, 04016229.

Ye, Z., Veneziano, D., Shi, X. (2013). Estimating statewide benefits of winter maintenance operations. Transportation Research Record: Journal of the Transportation Research Board, (2329), 17–23.

Zamagni, A. (2012). Life cycle sustainability assessment. International Journal of Life Cycle Assessment, 17, 373–376.

3

Winter Road Operations: A Historical Perspective

Leland D. Smithson

Retired AASHTO Snow and Ice Pooled Fund Cooperative Program (SICOP) Coordinator, Ames, IA 50010

3.1 Overview

The focus of this chapter is to highlight the important progress that State Departments of Transportation and local public works agencies have achieved in discovering, developing, and implementing sustainable winter road maintenance practices during the past three decades. This chapter will also document how research findings from the comprehensive U.S. Strategic Highway Research Program (SHRP), discoveries from the International Winter Maintenance Technology Scanning tours, and multistate consortium research efforts have produced better methods and equipment to accomplish winter maintenance, improve transportation safety and reliability and enhance winter hazard mitigation. Research findings and scanning tour discoveries were the important and necessary first steps to get progress started. Next, technology‐transfer techniques provided the key to understanding the research results and rigorous testing and field‐demonsteration efforts were the essential next steps to ensuring implementation success. The American Association of State Highway and Transportation Officials (AASHTO) provided the catalyst to keep the process moving by developing the vision for a national Winter Maintenance Program; establishing a committee to guide the program; implementing a funding process to support the program; creating a Snow and Ice list‐serve to connect, worldwide, the winter maintenance community; and developing a new approach for advanced training with a computer‐based training (CBT) program to accommodate the multiple learning styles found in the maintenance community and make technology transfer possible for all levels of academic ability. The bottom‐line results of this 30‐year effort have been improved mobility, reliability and safety, a situation which has provided a good return on the funds and time invested, while concurrently monitoring the impact on the receiving environment to ensure the total process is sustainable for the long term.

3.2 Pre‐Strategic Highway Research Program (Prior to 1987)

Prior to 1980, winter operations relied on hand‐me‐down knowledge and the experience of older field engineers and supervisors to interpret a radio or TV atmospheric weather forecast and decide what to do and when to do it. The response then was a reactive process of watching upstream as the storm approached and activating the plow crew after the snow had accumulated, to avoid public criticism of crews being on the road too early and thus wasting labor and fuel. The result was repeated application of brute force to scrape the compacted snow, combined with sanding curves and stop‐sign approaches to gain some traction.

Prior to 1960, a typical maintenance crew had a fleet consisting of medium‐duty gasoline‐powered dump trucks which were appropriately sized for summer maintenance operations. Each garage did have one or two four‐wheel‐drive heavy‐duty trucks and a motor grader that could be used for heavy plowing. Each truck had a chassis‐mounted spreader box which was installed just for winter operations. During extremely heavy snow some roads usually drifted shut and travel was not possible until the heavy‐duty truck or the motor grader was able to open at least a one‐way path. Some states had rotary snow plows which were used statewide to supplement the local crew efforts in opening blocked highways. While that response and equipment provided an acceptable level of service for winter maintenance 60 years ago, construction of the interstate highway system and its influence on the economy would add importance to the rationale for expanding the capabilities of the equipment fleet and providing an improved level of service with a goal of all‐season mobility.

During the 1970s, equipment gradually changed with the introduction of more powerful diesel engines, slip‐in spreaders with hydraulic‐powered material delivery systems, and quick connections for mounting snowplows. Rock salt became the preferred de‐icing chemical to aid in removal of packed snow/ice along with sand for improved traction. Progress during the 1970s was slow and the process of snow removal for the most part remained the application of brute force. However, that would change in the 1980s.

In the early 1980s, members of the Transportation Research Board (TRB) Winter Maintenance Committee attending the annual TRB meetings found themselves being introduced to and learning about the road weather information systems (RWIS) being installed and tested in Sweden. Technical papers were presented and discussed about how this new technology and fledgling science might someday lead to a better understanding of the influence of various factors on the road surface temperature and the possible usefulness of that data in winter road maintenance operations. The pavement temperature‐sensing equipment was not robust and needed to be field improved, data reliability was questionable, and how to use the data in snow and ice control operations was still being explored. The TRB Winter Maintenance Committee at that time had a very dedicated and diverse membership with members from the U.S., Canada, Europe and Japan. The committee meeting began at 7:30 PM and was scheduled to end about 10:00 PM. However, committee members found this subject so engaging that there was always an after meeting where discussion continued into the wee hours of the morning. (In fact, in 2016 this was still the case.) Many of the ideas from these early Winter Maintenance Committee discussions later found their way into the scope of research of the Strategic Highway Research Program (SHRP) winter maintenance operations program, which will be discussed in the next two sections of this chapter. Several of the Winter Maintenance Committee members, because they had considerable winter maintenance operations experience or had related academic knowledge, were selected for major roles in SHRP to guide that research.

3.3 The Strategic Highway Research Program (1987–1991)

In 1987 the Strategic Highway Research Program (SHRP) was established by Congress. SHRP was the largest highway applied‐research program ever undertaken, designed specifically to improve the performance and durability of the nation’s highways and to make them safer for motorists and highway workers. The $150 million research program and its resulting products were to be accomplished in five years. Congress then established programs in the Intermodal Surface Efficiency Act of 1991 to implement the SHRP products. See www.library.unt.edu/gpo/OTA/pubs/focus/fcs0998/shrp.htm for a more detailed discussion.

The SHRP program was directed by an executive committee consisting of top‐level managers from state highway agencies, industry and academia and operated as a unit of the National Research Council. The research was concentrated in four main areas: Asphalt; Concrete and Structures; Highway Operations (Maintenance and Work‐zone Safety); and Pavement Performance (Long‐term Pavement Performance Study). See www.fhwa.dot.gov/publications/publicroads/98marapr/shrp.cfm for more details on each of these areas.

The SHRP Highway Operations efforts developed SHRP products for Pavement Preservation and Repair; Snow and Ice Control; and Work‐zone Safety.

3.4 Post Strategic Highway Research Program (After 1991)

The SHRP program made major contributions to understanding and improving winter maintenance operations. Pioneering works by Blackburn, Boselly, Alger and others listed below were the foundational beginnings in developing anti‐icing and the use of liquid chemicals and showed how properly sited RWIS and pavement temperature forecasts coupled with pretreatments provided superior response with reductions in use of salt and sand. The process of connecting the winter maintenance community and the meteorological community began as the two communities worked together to field test and implement the RWIS (Boselly et al. 1993; Boselly and Ernst 1993) and anti‐icing (AI) (Blackburn et al. 1994; Alger et al. 1994) research completed in the early 1990s. The SHRP research was conducted in a relatively short time and although the research results were sound, technology transfer was difficult and did not produce consistent field results. Therefore, the Federal Highway Administration (FHWA)–Road Weather Management Program (RWMP) supported additional field studies in an effort to improve the basic understanding.

A project, labeled in field talk as TE‐28, which was short for FHWA Test and Evaluation project 28, enabled the winter maintenance and meteorological communities to concentrate their efforts to improve basic understanding of the microclimate at the road surface and develop appropriate treatment responses. The project extended the anti‐icing field‐testing begun under the SHRP program to roads with lower traffic, two‐lane roads, mountainous terrain and urban roads. A manual of practice was developed which pulled together the results of field tests into a description of winter maintenance operations’ decision‐making processes for eight winter‐storm scenarios (Ketcham et al. 1996).

To gain a better understanding of the road surface microclimate and to develop an appropriate operational response, the FHWA‐RWMP and the Office of the Federal Coordinator for Meteorology of the U.S. Department of Commerce built on the TE‐28 work by involving a wide range of stakeholders from the winter maintenance community in two collaborative efforts: the Surface Transportation Weather Decision Support Requirements (STWDSR) activity, which began in 1999, and the Weather Information for Surface Transportation (WIST) project, which started in 2000, to identify and fully define needs in the field of surface transportation weather (US Department of Commerce 2002).

Because there was such a wide range of disciplines, annual STWDSR and FHWA‐RWMP stakeholder meetings attended by practicing field maintenance personnel and private and public meteorologists were held, where problems were analyzed and solutions proposed and successful outcomes discussed. It soon became clear that in order to be proactive in applying pretreatments, the meteorological community needed to spend time in the field to completely understand the needs and requirements of the maintenance manager in planning and implementing a response plan for winter storms.

Consensus from the stakeholder meetings was to develop a Maintenance Decision Support System (MDSS) to integrate computerized winter maintenance practices developed from the TE‐28 manual of practice treatment recommendations and user requirements identified in the STWDSR and WIST efforts with state‐of‐the‐art weather forecasting models (Mahoney and Myers 2003). FHWA‐RWMP funded the development of a Federal Prototype MDSS the National Center for Atmospheric Research (NCAR) providing the technical lead. The U.S. Army Cold Regions Research and Engineering Laboratory, the Massachusetts Institute of Technology–Lincoln Laboratory, and the National Oceanic and Atmospheric Administration (NOAA) National Severe Storms Laboratory and Forecast Systems Laboratory added their expertise to the team.

The Federal Prototype MDSS was field tested and evaluated in Iowa during two winters, starting in 2002. The first winter, problems were traced to the road weather forecasting models, which were being field tested for the first time. Forecasting models were modified in the second winter and implementation went well with several of the recommended treatments applied without modification and other recommendations requiring only minor modifications. The third year of field demonstrations took place in the winter of 2004–2005 in central Colorado. This location provided new challenges for the MDSS prototype to address, due to the more complex terrain around the Denver area instead of the relatively flat terrain of central Iowa. The Colorado demonstration showed that weather forecasting was much more difficult on the leeward side of the Rocky Mountains, which subsequently led to significant improvements to the forecasting components of the Federal Prototype MDSS and corresponding improvements in the treatment recommendations. The Colorado DOT reported winter maintenance and start and stop times for precipitation were very close, resulting in increased efficiency in their operations.

Stakeholder meetings also identified the need to know more about the characteristics of the RWIS location so as to have a better understanding of the RWIS station data. Metadata such as location (i.e., on a hill or in a valley or flat open terrain, orientation to the sun, etc.) was needed. FHWA‐RWMP in response to this data issue began a project in 2003 to establish guidelines for siting RWIS environmental sensor stations (ESSs). The project was finished in 2005 and a report presenting recommended criteria for siting tower locations and mounting various sensors and the camera was published (Incrocci and Schmitt 2005). FHWA, in 2007–2008, updated the 2005 report using a stakeholder process to document user experience with implementing the 2005 guidelines (Manfredi et al. 2008).

Stakeholder meetings also brought into attention that the RWIS‐generated data had uncertain accuracy and were not in a common format. The U.S. DOT, FHWA‐RWMP, the Intelligent Transportation Systems (ITS) Joint Program Office (JPO) and NOAA in 2004 joined forces in a project called "Clarus" to collect weather observations, analyze the data for accuracy and then package the data into a common format that would meet the expectations of public and private end users. The result is a complete and accurate weather snapshot anywhere in the United States that is available to any user at any time. The Clarus program caught on quickly and by 2011 a total of 37 States, five