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NATIONAL NCHRPREPORT 526 COOPERATIVE HIGHWAY RESEARCH PROGRAM Snow and Ice Control: Guidelines for Materials and Methods

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TRANSPORTATION RESEARCH BOARD EXECUTIVE COMMITTEE 2004 (Membership as of January 2004) OFFICERS Chair: Michael S. Townes, President and CEO, Hampton Roads Transit, Hampton, VA Vice Chair: Joseph H. Boardman, Commissioner, New York State DOT Executive Director: Robert E. Skinner, Jr., Transportation Research Board MEMBERS MICHAEL W. BEHRENS, Executive Director, Texas DOT SARAH C. CAMPBELL, President, TransManagement, Inc., Washington, DC E. DEAN CARLSON, Director, Carlson Associates, Topeka, KS JOHN L. CRAIG, Director, Nebraska Department of Roads DOUGLAS G. DUNCAN, President and CEO, FedEx Freight, Memphis, TN GENEVIEVE GIULIANO, Director, Metrans Transportation Center and Professor, School of Policy, Planning, and Development, USC, Los Angeles BERNARD S. GROSECLOSE, JR., President and CEO, South Carolina State Ports Authority SUSAN HANSON, Landry University Professor of Geography, Graduate School of Geography, Clark University JAMES R. HERTWIG, President, Landstar Logistics, Inc., Jacksonville, FL HENRY L. HUNGERBEELER, Director, Missouri DOT ADIB K. KANAFANI, Cahill Professor of Civil Engineering, University of California, Berkeley RONALD F. KIRBY, Director of Transportation Planning, Metropolitan Washington Council of Governments HERBERT S. LEVINSON, Principal, Herbert S. Levinson Transportation Consultant, New Haven, CT SUE MCNEIL, Director, Urban Transportation Center and Professor, College of Urban Planning and Public Affairs, University of Illinois, Chicago MICHAEL D. MEYER, Professor, School of Civil and Environmental Engineering, Georgia Institute of Technology KAM MOVASSAGHI, Secretary of Transportation, Louisiana Department of Transportation and Development CAROL A. MURRAY, Commissioner, New Hampshire DOT JOHN E. NJORD, Executive Director, Utah DOT DAVID PLAVIN, President, Airports Council International, Washington, DC JOHN REBENSDORF, Vice President, Network and Service Planning, Union Pacific Railroad Co., Omaha, NE PHILIP A. SHUCET, Commissioner, Virginia DOT C. MICHAEL WALTON, Ernest H. Cockrell Centennial Chair in Engineering, University of Texas, Austin LINDA S. WATSON, General Manager, Corpus Christi Regional Transportation Authority, Corpus Christi, TX MARION C. BLAKEY, Federal Aviation Administrator, U.S.DOT (ex officio) SAMUEL G. BONASSO, Acting Administrator, Research and Special Programs Administration, U.S.DOT (ex officio) REBECCA M. BREWSTER, President and COO, American Transportation Research Institute, Smyrna, GA (ex officio) GEORGE BUGLIARELLO, Chancellor, Polytechnic University and Foreign Secretary, National Academy of Engineering (ex officio) THOMAS H. COLLINS (Adm., U.S. Coast Guard), Commandant, U.S. Coast Guard (ex officio) JENNIFER L. DORN, Federal Transit Administrator, U.S.DOT (ex officio) ROBERT B. FLOWERS (Lt. Gen., U.S. Army), Chief of Engineers and Commander, U.S. Army Corps of Engineers (ex officio) EDWARD R. HAMBERGER, President and CEO, Association of American Railroads (ex officio) JOHN C. HORSLEY, Executive Director, American Association of State Highway and Transportation Officials (ex officio) RICK KOWALEWSKI, Deputy Director, Bureau of Transportation Statistics, U.S.DOT (ex officio) WILLIAM W. MILLAR, President, American Public Transportation Association (ex officio) MARY E. PETERS, Federal Highway Administrator, U.S.DOT (ex officio) SUZANNE RUDZINSKI, Director, Transportation and Regional Programs, U.S. Environmental Protection Agency (ex officio) JEFFREY W. RUNGE, National Highway Traffic Safety Administrator, U.S.DOT (ex officio) ALLAN RUTTER, Federal Railroad Administrator, U.S.DOT (ex officio) ANNETTE M. SANDBERG, Federal Motor Carrier Safety Administrator, U.S.DOT (ex officio) WILLIAM G. SCHUBERT, Maritime Administrator, U.S.DOT (ex officio) ROBERT A. VENEZIA, Program Manager of Public Health Applications, National Aeronautics and Space Administration (ex officio) NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Transportation Research Board Executive Committee Subcommittee for NCHRP MICHAEL S. TOWNES, Hampton Roads Transit, Hampton, VA JOHN C. HORSLEY, American Association of State Highway (Chair) and Transportation Officials JOSEPH H. BOARDMAN, New York State DOT MARY E. PETERS, Federal Highway Administration GENEVIEVE GIULIANO, University of Southern California, ROBERT E. SKINNER, JR., Transportation Research Board Los Angeles C. MICHAEL WALTON, University of Texas, Austin

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NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM NCHRP REPORT 526 Snow and Ice Control: Guidelines for Materials and Methods ROBERT R. BLACKBURN AND KARIN M. BAUER Midwest Research Institute Kansas City, MO DUANE E. AMSLER, SR. AFM Engineering Services Slingerlands, NY S. EDWARD BOSELLY Weather Solutions Group Olympia, WA A. DEAN MCELROY Consultant Overland Park, KS S UBJECT A REAS Maintenance Research Sponsored by the American Association of State Highway and Transportation Officials in Cooperation with the Federal Highway Administration TRANSPORTATION RESEARCH BOARD WASHINGTON, D.C. 2004 www.TRB.org

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NATIONAL COOPERATIVE HIGHWAY RESEARCH NCHRP REPORT 526 PROGRAM Systematic, well-designed research provides the most effective Project F6-13 FY'98 approach to the solution of many problems facing highway administrators and engineers. Often, highway problems are of local ISSN 0077-5614 interest and can best be studied by highway departments ISBN 0-309-08799-6 individually or in cooperation with their state universities and Library of Congress Control Number 2004109204 others. However, the accelerating growth of highway transportation develops increasingly complex problems of wide interest to 2004 Transportation Research Board highway authorities. These problems are best studied through a coordinated program of cooperative research. Price $19.00 In recognition of these needs, the highway administrators of the American Association of State Highway and Transportation Officials initiated in 1962 an objective national highway research program employing modern scientific techniques. This program is supported on a continuing basis by funds from participating member states of the Association and it receives the full cooperation and support of the Federal Highway Administration, United States NOTICE Department of Transportation. The project that is the subject of this report was a part of the National Cooperative The Transportation Research Board of the National Academies Highway Research Program conducted by the Transportation Research Board with the was requested by the Association to administer the research approval of the Governing Board of the National Research Council. Such approval program because of the Board's recognized objectivity and reflects the Governing Board's judgment that the program concerned is of national understanding of modern research practices. The Board is uniquely importance and appropriate with respect to both the purposes and resources of the suited for this purpose as it maintains an extensive committee National Research Council. structure from which authorities on any highway transportation The members of the technical committee selected to monitor this project and to review subject may be drawn; it possesses avenues of communications and this report were chosen for recognized scholarly competence and with due cooperation with federal, state and local governmental agencies, consideration for the balance of disciplines appropriate to the project. The opinions and universities, and industry; its relationship to the National Research conclusions expressed or implied are those of the research agency that performed the Council is an insurance of objectivity; it maintains a full-time research, and, while they have been accepted as appropriate by the technical committee, research correlation staff of specialists in highway transportation they are not necessarily those of the Transportation Research Board, the National matters to bring the findings of research directly to those who are in Research Council, the American Association of State Highway and Transportation a position to use them. Officials, or the Federal Highway Administration, U.S. Department of Transportation. The program is developed on the basis of research needs Each report is reviewed and accepted for publication by the technical committee identified by chief administrators of the highway and transportation according to procedures established and monitored by the Transportation Research departments and by committees of AASHTO. Each year, specific Board Executive Committee and the Governing Board of the National Research areas of research needs to be included in the program are proposed Council. to the National Research Council and the Board by the American Association of State Highway and Transportation Officials. Research projects to fulfill these needs are defined by the Board, and qualified research agencies are selected from those that have submitted proposals. Administration and surveillance of research contracts are the responsibilities of the National Research Council and the Transportation Research Board. Published reports of the The needs for highway research are many, and the National NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Cooperative Highway Research Program can make significant contributions to the solution of highway transportation problems of are available from: mutual concern to many responsible groups. The program, however, is intended to complement rather than to substitute for or Transportation Research Board duplicate other highway research programs. Business Office 500 Fifth Street, NW Washington, DC 20001 and can be ordered through the Internet at: Note: The Transportation Research Board of the National Academies, the National Research Council, the Federal Highway Administration, the American Association of State Highway and Transportation Officials, and the individual http://www.national-academies.org/trb/bookstore states participating in the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturers' names appear herein solely because they are considered essential to the object of this report. Printed in the United States of America

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The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished schol- ars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. On the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and techni- cal matters. Dr. Bruce M. Alberts is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Acad- emy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achieve- ments of engineers. Dr. William A. Wulf is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, on its own initiative, to identify issues of medical care, research, and education. Dr. Harvey V. Fineberg is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy's purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Acad- emy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both the Academies and the Institute of Medicine. Dr. Bruce M. Alberts and Dr. William A. Wulf are chair and vice chair, respectively, of the National Research Council. The Transportation Research Board is a division of the National Research Council, which serves the National Academy of Sciences and the National Academy of Engineering. The Board's mission is to promote innovation and progress in transportation through research. In an objective and interdisciplinary setting, the Board facilitates the sharing of information on transportation practice and policy by researchers and practitioners; stimulates research and offers research management services that promote technical excellence; provides expert advice on transportation policy and programs; and disseminates research results broadly and encourages their implementation. The Board's varied activities annually engage more than 5,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. The program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individuals interested in the development of transportation. www.TRB.org www.national-academies.org

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COOPERATIVE RESEARCH PROGRAMS STAFF FOR NCHRP REPORT 526 ROBERT J. REILLY, Director, Cooperative Research Programs CRAWFORD F. JENCKS, Manager, National Cooperative Highway Research Program AMIR N. HANNA, Senior Program Officer EILEEN P. DELANEY, Managing Editor NCHRP PROJECT F6-13 PANEL Field of Maintenance--Area of Snow and Ice Control DENNIS H. FILE, Springfield, IL (formerly with Illinois DOT) (Chair) JOSEPH DOHERTY, New York State DOT LARRY W. FREVERT, Kansas City (MO) Department of Public Works RICHARD A. GILMORE, Maryland State Highway Administration DANIEL P. JOHNSTON, South Dakota DOT DAVID A. KUEMMEL, Marquette University L. DAVID MINSK, Hanover, NH RICHARD J. NELSON, Nevada DOT PAUL PISANO, FHWA Liaison Representative FRANK N. LISLE, TRB Liaison Representative

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This report provides guidelines for selecting roadway snow and ice control strate- FOREWORD gies and tactics for a wide range of winter maintenance operating conditions. These By Amir N. Hanna guidelines apply to highways, roads, streets, and other paved surfaces that carry motor Staff Officer vehicles--under state or local jurisdictions. The guidelines will assist winter mainte- Transportation Research nance personnel in selecting the appropriate level-of-service (LOS)-driven roadway Board snow and ice control operations and will help effectively manage snow and ice control resources. The report is a useful resource for state and local highway agency personnel and others involved in snow and ice control. Snow and ice control on the U.S. highway system consumes billion of dollars--in direct costs and costs associated with corrosion and environmental impacts--each year. Strategies and tactics that employ solid and liquid chemicals, abrasives, and mechanical methods--individually or in combination--have been used by state and local agencies. In spite of many studies of issues associated with snow and ice control treatments, widely accepted guidelines for selecting roadway snow and ice control strategies and tactics for specific climatic, site, and traffic conditions have not emerged. Without such guidelines, the process of selecting treatment strategies and tactics that meet highway agency objectives can be difficult and costly. NCHRP Project 6-13 was conducted to address this need. Under NCHRP Project 6-13, "Guidelines for Snow and Ice Control Materials and Methods," Midwest Research Institute of Kansas City, Missouri was assigned the objective of developing guidelines--applicable to state and local agencies--for select- ing roadway snow and ice control strategies and tactics for specific ranges of climatic and traffic conditions found in the United States. These strategies and tactics refer to the combinations of materials, equipment, and methods--both chemical and physical-- used in snow and ice control to achieve a defined LOS; they also include road-weather information systems and weather forecasting. To accomplish this objective, the researchers performed the following tasks: 1. Identified the climatic, site, and traffic conditions that affect the selection of snow and ice control strategies and tactics to achieve agency objectives (e.g., LOS) and listed in a rank-order the criteria necessary to assess the performance of treatments. 2. Identified the snow and ice control strategies and tactics in current use that may be applicable to U.S. conditions and highlighted for each strategy and tactic the conditions of use, selection criteria, evaluation methods, effectiveness, and related problems. 3. Identified specific snow and ice control strategies and tactics that merited fur- ther evaluation and developed a plan for their field evaluation in different envi- ronments under different site and traffic conditions.

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4. Conducted investigations of several potential snow and ice strategy and tactic combinations during three winter seasons and collected information necessary to relate the effectiveness of each of these combinations to the climatic, site, and traffic conditions. 5. Developed guidelines that can be used for selecting appropriate snow and ice control strategies and tactics for specific climatic, site, and traffic conditions to achieve agency objectives. The following five primary combinations (1 through 5) were evaluated at different locations over three winter periods under a variety of weather and traffic conditions: 1. Anti-icing strategy with appropriate chemical forms (e.g., solids and prewetted solids) on lower-volume primary highways and local roads followed by a sub- sequent strategy of mechanical removal of snow and ice together with friction enhancement, if necessary. 2. Anti-icing strategy with appropriate chemical forms (e.g., solids, prewetted solids, and liquids) at selected highway locations such as hills, curves, inter- sections, grades, and selected bridge decks. 3. Anti-icing or deicing strategy with appropriate chemical forms on lower- volume primary highways and local road systems. 4. Anti-icing strategy with liquid chemical applications on bridge decks to prevent preferential icing. 5. Mechanical snow and ice removal strategy with abrasives prewetted with liq- uid chemicals. A total of 24 highway agencies (13 state, 1 provincial, 4 county, and 6 city or town) made an attempt at testing the five strategy/tactic combinations at a total of 51 site locations over the three-winter periods; three highway agencies provided test data for the same location over all three winters. However, adjustments were made by some highway agencies to the assigned strategy/tactic combinations during some winter weather events because of weather-related circumstances and other limitations. These adjustments resulted in the following three additional strategy/tactic combinations (6 through 8): 6. Chemical priority strategy with straight chemicals (solid, prewet solid, or liq- uid) throughout an event to the extent possible and an occasional application of abrasives/chemical mixture. 7. Abrasive priority strategy with abrasives (pure or mixed with chemicals) throughout an event to the extent possible and an occasional application of straight chemicals (solid, prewet solid, or liquid). 8. Plowing only strategy without the use of snow and ice control materials (chem- icals and/or abrasives) throughout the entire winter weather event. To evaluate alternative strategy/tactic combinations, the researchers considered possible indicators/measures of effectiveness and developed a condition index-- termed Pavement Snow and Ice Condition (PSIC) index--that describes the road con- dition in one of seven levels. These levels range from a pavement surface that remains in a bare/wet condition at all times (Condition 1) to a pavement surface that is cov- ered with a significant buildup of packed snow and ice (Condition 6) and even a pave- ment surface that is exposed to drifting and excessive unplowed snow to warrant tem- porary closure (Condition 7). The index was used to evaluate both within-event and end-of-event LOS achieved by the winter maintenance treatments for comparing the effectiveness of the different strategy/tactic combinations. The researchers also inves-

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tigated the factors influencing the choice of materials, their form, and associated appli- cation rates. The findings of this research pointed out the importance of (1) ensuring that snow and ice control strategy/tactic combinations are LOS driven; (2) using nowcasting results, materials characteristics, traffic volume, and cycle time considerations in the treatment decision making; and (3) providing flexible winter maintenance operations to deal with the variety of precipitation types, especially those occurring within a given weather event. Results of the analytical and field investigations conducted in this research were used to develop the guidelines for winter maintenance materials and methods presented in this report. These guidelines will assist in selecting materials and methods that best address LOS, weather, site, and traffic conditions and, therefore, be useful to highway agencies and contracting firms involved in snow and ice control work.

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CONTENTS 1 CHAPTER 1 Introduction 3 CHAPTER 2 Level of Service How Agencies Characterize Level of Service, 3 Recommended Level of Service Goals, 3 Assigning Level of Service Goals, 3 Performance Measuring of Level of Service, 3 Snow and Ice Control Operational Considerations Relating to Level of Service, 4 6 CHAPTER 3 Snow and Ice Control Operational Considerations Climate Conditions, 6 Weather Conditions, 6 Site Conditions, 6 Traffic Conditions, 6 Summary of Snow and Ice Control Operational Considerations, 7 9 CHAPTER 4 Performance-Based Level of Service The "Design" Winter Weather Event, 9 Within-Winter Weather Event Level of Service, 9 After-End-of-Winter Weather Event Level of Service, 9 Establishing Level of Service Goals, 9 11 CHAPTER 5 Strategies and Tactics and Their Application to Support Level of Service Choices Anti-icing, 11 Deicing, 11 Mechanical Removal of Snow and Ice Together with Friction Enhancement, 11 Mechanical Removal Alone, 12 Traction Enhancement, 12 Combinations of Strategies, 12 Summary, 12 13 CHAPTER 6 Factors Influencing the Choice of Materials, Their Form, and Associated Application Rates Dilution Potential, 13 Properties of Ice Control Materials, 14 15 CHAPTER 7 Recommended Snow and Ice Control Practices Strategies and Level of Service, 15 Treatment Selection, 16 18 CHAPTER 8 Recommended Operational Guidelines for Winter Maintenance Field Personnel Solid Ice Control Chemicals, 18 Liquid Ice Control Chemicals, 20 Abrasives, 25 26 REFERENCES A-1 ATTACHMENT 1 Using Road and Weather Information to Make Chemical Ice Control Treatment Decisions B-1 ATTACHMENT 2 Example of Designing a Chemical Snow and Ice Control Treatment