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Design Practices for Rock Slopes and Rockfall Management A Synthesis of Highway Practice Darren Beckstrand Brent Black Benjamin George Noah Kimmes Aine Mines Danica Ruud Landslide Technology Portland, OR 2022 Research sponsored by the American Association of State Highway and Transportation Ofcials in cooperation with the Federal Highway Administration Subscriber Categories Highways â¢ Design â¢ Geotechnology N A T I O N A L C O O P E R A T I V E H I G H W A Y R E S E A R C H P R O G R A M NCHRP SYNTHESIS 588
Published reports of the NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM are available from Transportation Research Board Business Office 500 Fifth Street, NW Washington, DC 20001 and can be ordered through the Internet by going to https://www.mytrb.org/MyTRB/Store/default.aspx Printed in the United States of America NCHRP SYNTHESIS 588 Project 20-05, Topic 52-18 ISSN 0547-5570 ISBN 978-0-309-68707-2 Library of Congress Control Number 2022938480 Â© 2022 by the National Academy of Sciences. National Academies of Sciences, Engineering, and Medicine and the graphical logo are trade- marks of the National Academy of Sciences. All rights reserved. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FTA, GHSA, NHTSA, or TDC endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. Photo credit: Jonathan Tymick, Alaska Department of Transportation and Public Facilities. Rockfall mitigation design team performing reconnaissance on the Seward Highway, south of Anchorage. NOTICE The report was reviewed by the technical panel and accepted for publication according to procedures established and overseen by the Transportation Research Board and approved by the National Academies of Sciences, Engineering, and Medicine. The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research and are not necessarily those of the Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; the FHWA; or the program sponsors. The Transportation Research Board does not develop, issue, or publish standards or specifi- cations. The Transportation Research Board manages applied research projects which pro- vide the scientific foundation that may be used by Transportation Research Board sponsors, industry associations, or other organizations as the basis for revised practices, procedures, or specifications. The Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; and the sponsors of the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturersâ names or logos appear herein solely because they are considered essential to the object of the report. NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed, and implementable research is the most effective way to solve many problems facing state departments of transportation (DOTs) administrators and engineers. Often, highway problems are of local or regional interest and can best be studied by state DOTs individually or in cooperation with their state universities and others. However, the accelerating growth of highway transporta- tion results in increasingly complex problems of wide interest to high- way authorities. These problems are best studied through a coordinated program of cooperative research. Recognizing this need, the leadership of the American Association of State Highway and Transportation Officials (AASHTO) in 1962 ini- tiated an objective national highway research program using modern scientific techniquesâthe National Cooperative Highway Research Program (NCHRP). NCHRP is supported on a continuing basis by funds from participating member states of AASHTO and receives the full cooperation and support of the Federal Highway Administration (FHWA), United States Department of Transportation, under Agree- ment No. 693JJ31950003. The Transportation Research Board (TRB) of the National Academies of Sciences, Engineering, and Medicine was requested by AASHTO to administer the research program because of TRBâs recognized objectivity and understanding of modern research practices. TRB is uniquely suited for this purpose for many reasons: TRB maintains an extensive com- mittee structure from which authorities on any highway transportation subject may be drawn; TRB possesses avenues of communications and cooperation with federal, state, and local governmental agencies, univer- sities, and industry; TRBâs relationship to the National Academies is an insurance of objectivity; and TRB maintains a full-time staff of special- ists in highway transportation matters to bring the findings of research directly to those in a position to use them. The program is developed on the basis of research needs iden- tified by chief administrators and other staff of the highway and transportation departments, by committees of AASHTO, and by the FHWA. Topics of the highest merit are selected by the AASHTO Special Committee on Research and Innovation (R&I), and each year R&Iâs recommendations are proposed to the AASHTO Board of Direc- tors and the National Academies. Research projects to address these topics are defined by NCHRP, and qualified research agencies are selected from submitted proposals. Administration and surveillance of research contracts are the responsibilities of the National Academies and TRB. The needs for highway research are many, and NCHRP can make significant contributions to solving highway transportation problems of mutual concern to many responsible groups. The program, however, is intended to complement, rather than to substitute for or duplicate, other highway research programs.
e National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, non- governmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Marcia McNutt is president. e National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. John L. Anderson is president. e National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president. e three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. e National Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine. Learn more about the National Academies of Sciences, Engineering, and Medicine at www.nationalacademies.org. e Transportation Research Board is one of seven major programs of the National Academies of Sciences, Engineering, and Medicine. e mission of the Transportation Research Board is to provide leadership in transportation improvements and innovation through trusted, timely, impartial, and evidence-based information exchange, research, and advice regarding all modes of transportation. e Boardâs varied activities annually engage about 8,000 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. e 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. Learn more about the Transportation Research Board at www.TRB.org.
CRP STAFF FOR NCHRP SYNTHESIS 588 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs Waseem Dekelbab, Associate Program Manager, National Cooperative Highway Research Program Jo Allen Gause, Senior Program Officer Deborah Irvin, Program Coordinator Natalie Barnes, Director of Publications Heather DiAngelis, Associate Director of Publications NCHRP PROJECT 20-05 PANEL Joyce N. Taylor, Maine Department of Transportation, Augusta, ME (Chair) Melissa Batula, Pennsylvania Department of Transportation, Harrisburg, PA Anita K. Bush, Nevada Department of Transportation, Carson City, NV Joseph D. Crabtree, Kentucky Transportation Center, Lexington, KY Allison R. Hardt, Maryland Department of Transportation, Baltimore, MD Mostafa Jamshidi, Nebraska Department of Transportation, Lincoln, NE Cynthia L. Jones, Ohio Department of Transportation, Columbus, OH Jessie X. Jones, Arkansas Department of Transportation, Little Rock, AR Brenda Moore, Cary, NC Randall R. Park, Avenue Consultants, Taylorsville, UT Brian Worrel, Iowa Department of Transportation, Ames, IA Jack D. Jernigan, FHWA Liaison Jim T. McDonnell, AASHTO Liaison Stephen F. Maher, TRB Liaison TOPIC 52-18 PANEL Bob P. Group, Colorado Department of Transportation, Denver, CO Joe Hudak, Minnesota Department of Transportation, Maplewood, MN Jody C. Kuhne, North Carolina Department of Transportation, Asheville, NC Kate Maguire, Maine Department of Transportation, Augusta, ME Anil K. Patnaik, University of Akron, Akron, OH Krystle J. Pelham, New Hampshire Department of Transportation, Concord, NH Mark J. Vessely, BGC Engineering Inc., Golden, CO Carrington Wright, Texas Department of Transportation, Houston, TX Jennifer Nicks, FHWA Liaison Nancy M. Whiting, TRB Liaison C O O P E R A T I V E R E S E A R C H P R O G R A M S
ABOUT THE NCHRP SYNTHESIS PROGRAM Highway administrators, engineers, and researchers often face problems for which information already exists, either in documented form or as undocumented experience and practice. This infor- mation may be fragmented, scattered, and unevaluated. As a consequence, full knowledge of what has been learned about a problem may not be brought to bear on its solution. Costly research findings may go unused, valuable experience may be overlooked, and due consideration may not be given to recommended practices for solving or alleviating the problem. There is information on nearly every subject of concern to highway administrators and engineers. Much of it derives from research or from the work of practitioners faced with problems in their day- to-day work. To provide a systematic means for assembling and evalu ating such useful information and to make it available to the entire highway community, the American Association of State High- way and Transportation Officialsâthrough the mechanism of the National Cooperative Highway Research Programâauthorized the Transportation Research Board to undertake a continuing study. This study, NCHRP Project 20-05, âSynthesis of Information Related to Highway Practices,â searches out and synthesizes useful knowledge from all available sources and prepares concise, documented reports on specific topics. Reports from this endeavor constitute an NCHRP report series, Synthesis of Highway Practice. This synthesis series reports on current knowledge and practice, in a compact format, without the detailed directions usually found in handbooks or design manuals. Each report in the series provides a compendium of the best knowledge available on those measures found to be the most successful in resolving specific problems. FOREWORD By Jo Allen Gause Staff Officer Transportation Research Board While there are no national standards for rock slope design and rockfall management, many state departments of transportation (DOTs) have developed their own design goals and objectives. The objective of this synthesis is to document DOT practices for the design of rock slopes and rockfall mitigation systems. Information for this study was gathered through a literature review, a survey of state DOTs, and follow-up interviews with selected agencies. Four case examples provide additional information on the topic. Darren Beckstrand, Brent Black, Benjamin George, Noah Kimmes, Aine Mines, and Danica Ruud, Landslide Technology, collected and synthesized the information and wrote the report. The members of the topic panel are acknowledged on page iv. This synthesis is an immediately useful document that records practices that were acceptable within the limitations of the knowledge available at the time of its preparation. As progress in research and practice continues, new knowledge will be added to that now at hand.
Note: Photographs, figures, and tables in this report may have been converted from color to grayscale for printing. The electronic version of the report (posted on the web at www.nap.edu) retains the color versions. 1 Summary 4 Chapter 1 Introduction 4 Role of Effective Rock Slope and Rockfall Mitigation Design 5 Synthesis Objectives 5 Synthesis Methodology 5 Terminology 8 Report Organization 9 Chapter 2 Literature Review 9 Slope Hazard Rating Systems and Site Selection 10 Slope Stability 10 Mitigation Measures and Selection Considerations 13 Chapter 3 State of the Practice 13 Questionnaire Responses 24 Chapter 4 Case Examples 25 Oregon Department of Transportation 26 Tennessee Department of Transportation 27 Utah Department of Transportation 28 Virginia Department of Transportation 30 Chapter 5 Summary of Findings 30 Design Goal Utilization 31 Site-Specific Goals 31 Pragmatism-Driven Decision Making 31 Future Research Opportunities 33 References 35 Appendix A Survey Questionnaire 60 Appendix B Survey Responses 83 Appendix C Individual Survey Responses 147 Appendix D Department of Transportationâ Provided Documentation C O N T E N T S