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WINTER HIGHWAY OPERATIONS SUMMARY Winter highway operations now integrate snow and ice control strategies and activities, traveler information, traffic operations, weather effects, environmental impacts, incident management, and customer satisfaction. Winter weather is experienced as snow and ice accu- mulation on the pavement, fog and reduced visibility, rockslides, flooding, and high winds throughout North America. This synthesis focuses on the changes as reported by a representa- tion of U.S. state and Canadian provincial agencies between 1994 and 2004 to practices and strategies being used to control the impacts of winter weather on the safe and efficient move- ment of traffic. Government agencies tasked with maintaining levels of service on the vast system of high- ways affected by winter weather resort to a variety of approaches. They use various technolo- gies to forecast winter storms and the degree of impact to highways. Such agencies maintain travel way functionality armed with both information technologies and advanced snow fight- ing equipment and materials. Maintenance trucks are equipped with plows, ice-controlling chemical reserves and associated spreading machinery, deployment optimizing communica- tions systems, and advanced control systems for all of these devices. All of this represents a significant expenditure of public funds aimed at keeping vital highways operational through- out inclement winter weather. The FHWA Road Weather Management website, "Welcome to Road Weather Manage- ment" (http://ops.fhwa.dot.gov/weather) reports that state and local agencies spend more than $2 billion annually on snow and ice control operations and more than $5 billion annually for infrastructure repair as the result of snow and ice damage. Some of this significant infrastructure damage has been attributed to winter operations policies and practices, such as Oregon's experience with studded tire use by the public. This represents a significant expenditure for highway agencies and therefore deserves attention and effort toward optimizing winter maintenance techniques and practices. The variety of practices currently in use represents both expected differences in the evolution of winter high- way control from agency to agency and the necessary variability owing to unique weather con- ditions experienced in some regions. States, provinces, and local governments operate their own maintenance equipment or hire contract services. There is no uniform measure or standard for winter road maintenance in North America. Local and regional operations are guided by multiple levels of service devel- oped to meet customer expectations, budgets, and standards of care concerns. In general, higher classifications of highways receive more attention. In the United States, routes on the 160,000-mi (256,000-km) National Highway System network, primarily Interstate express- ways and primary roads, are typically cleared more quickly and completely. Similar condi- tions exist for the approximately 15,000-mi (24,023-km) Canadian National Highway Sys- tem. Specialized policies exist for critical areas such as mountain passes that have traction device requirements for vehicles, snow emergency routes that will be cleared of parked cars, and avalanche hazard zones.

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2 Treatment to prevent bonding of snow and ice to the road surface (anti-icing) is increas- ingly used; however, classic methodologies such as snow removal by plowing, with chemical and abrasive application, remain the mainstay of winter operations. These strategies have changed in the 10 years from 1994 to 2004 and will undoubtedly continue to evolve, inte- grating new technological advances as they emerge and prove their worth. Of note are the recent advancements that have been developed through intelligent transportation systems ini- tiatives. These components represent the overlap between highway and transportation needs and the use of advanced or emerging technology applications. Trends toward greater use of anti-icing techniques have increased reliance on roadside weather and surface pavement con- dition observations as well as task-specific weather forecasts. Although having been in use before 1994, Road Weather Information Systems (RWIS) have gained tremendous application throughout the United States and Canada. RWIS gener- ally continue to be part of maintenance divisions. Although state responsibilities vary, active deployments of new RWIS are under the purview of intelligent transportation systems divi- sions within many agencies. Increased use of RWIS is particularly true for agencies with remote highway segments that are prone to severe winter weather. Advances in the tech- nologies used by roadside RWIS Environmental Sensor Stations (RWISESS) and the asso- ciated communications have expanded the utility of remote weather stations. The use of cam- eras in conjunction with the more traditional RWISESS components has demonstrated the value of visual confirmation of near-real-time weather data. Maintenance managers have been required to further stretch finite resources to address greater public demand for better and more consistent levels of service. The benefits of the con- tinuing move in this direction are found in the increasingly innovative approaches to the man- agement of personnel, equipment, and materials. Experienced and well-trained highway main- tenance personnel are the most valuable resource in transportation agencies' winter programs. Deicing and anti-icing chemical use is an area of change, with many chemical and chemical combinations available. Emphasis on the protection of the natural environment and minimizing impacts to the delicate balances found there have been significantly felt at the winter maintenance level. Responses to a questionnaire indicated that the use of abrasives such as sand appears to have diminished, in part, as the result of the environmental impacts associated with airborne particles generated indirectly through their use. Many agencies are experiencing more stringent storage, clean-up, and disposal requirements for both chemicals and abrasives. Efforts to cost-effectively minimize the use of deicing and anti-icing chemi- cals are both less detrimental to the environment and a prudent use of public resources. Costs resulting from corrosion to public and agency vehicles, corrosion of the infrastructure, and infrastructure damage that results from not maintaining travel way traction levels compound these efforts.