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NATIONAL NCHRP REPORT 613 COOPERATIVE HIGHWAY RESEARCH PROGRAM Guidelines for Selection of Speed Reduction Treatments at High-Speed Intersections

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TRANSPORTATION RESEARCH BOARD 2008 EXECUTIVE COMMITTEE* OFFICERS CHAIR: Debra L. Miller, Secretary, Kansas DOT, Topeka VICE CHAIR: Adib K. Kanafani, Cahill Professor of Civil Engineering, University of California, Berkeley EXECUTIVE DIRECTOR: Robert E. Skinner, Jr., Transportation Research Board MEMBERS J. Barry Barker, Executive Director, Transit Authority of River City, Louisville, KY Allen D. Biehler, Secretary, Pennsylvania DOT, Harrisburg John D. Bowe, President, Americas Region, APL Limited, Oakland, CA Larry L. Brown, Sr., Executive Director, Mississippi DOT, Jackson Deborah H. Butler, Executive Vice President, Planning, and CIO, Norfolk Southern Corporation, Norfolk, VA William A.V. Clark, Professor, Department of Geography, University of California, Los Angeles David S. Ekern, Commissioner, Virginia DOT, Richmond Nicholas J. Garber, Henry L. Kinnier Professor, Department of Civil Engineering, University of Virginia, Charlottesville Jeffrey W. Hamiel, Executive Director, Metropolitan Airports Commission, Minneapolis, MN Edward A. (Ned) Helme, President, Center for Clean Air Policy, Washington, DC Will Kempton, Director, California DOT, Sacramento Susan Martinovich, Director, Nevada DOT, Carson City Michael D. Meyer, Professor, School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta Michael R. Morris, Director of Transportation, North Central Texas Council of Governments, Arlington Neil J. Pedersen, Administrator, Maryland State Highway Administration, Baltimore Pete K. Rahn, Director, Missouri DOT, Jefferson City Sandra Rosenbloom, Professor of Planning, University of Arizona, Tucson Tracy L. Rosser, Vice President, Corporate Traffic, Wal-Mart Stores, Inc., Bentonville, AR Rosa Clausell Rountree, Executive Director, Georgia State Road and Tollway Authority, Atlanta Henry G. (Gerry) Schwartz, Jr., Chairman (retired), Jacobs/Sverdrup Civil, Inc., St. Louis, MO C. Michael Walton, Ernest H. Cockrell Centennial Chair in Engineering, University of Texas, Austin Linda S. Watson, CEO, LYNX­Central Florida Regional Transportation Authority, Orlando Steve Williams, Chairman and CEO, Maverick Transportation, Inc., Little Rock, AR EX OFFICIO MEMBERS Thad Allen (Adm., U.S. Coast Guard), Commandant, U.S. Coast Guard, Washington, DC Joseph H. Boardman, Federal Railroad Administrator, U.S.DOT Rebecca M. Brewster, President and COO, American Transportation Research Institute, Smyrna, GA Paul R. Brubaker, Research and Innovative Technology Administrator, U.S.DOT George Bugliarello, Chancellor, Polytechnic University of New York, Brooklyn, and Foreign Secretary, National Academy of Engineering, Washington, DC Sean T. Connaughton, Maritime Administrator, U.S.DOT LeRoy Gishi, Chief, Division of Transportation, Bureau of Indian Affairs, U.S. Department of the Interior, Washington, DC Edward R. Hamberger, President and CEO, Association of American Railroads, Washington, DC John H. Hill, Federal Motor Carrier Safety Administrator, U.S.DOT John C. Horsley, Executive Director, American Association of State Highway and Transportation Officials, Washington, DC Carl T. Johnson, Pipeline and Hazardous Materials Safety Administrator, U.S.DOT J. Edward Johnson, Director, Applied Science Directorate, National Aeronautics and Space Administration, John C. Stennis Space Center, MS William W. Millar, President, American Public Transportation Association, Washington, DC Nicole R. Nason, National Highway Traffic Safety Administrator, U.S.DOT James Ray, Acting Administrator, Federal Highway Administration, U.S.DOT James S. Simpson, Federal Transit Administrator, U.S.DOT Robert A. Sturgell, Acting Administrator, Federal Aviation Administration, U.S.DOT Robert L. Van Antwerp (Lt. Gen., U.S. Army), Chief of Engineers and Commanding General, U.S. Army Corps of Engineers, Washington, DC *Membership as of May 2008.

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NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM NCHRP REPORT 613 Guidelines for Selection of Speed Reduction Treatments at High-Speed Intersections Brian Ray Wayne Kittelson Julia Knudsen Brandon Nevers Paul Ryus Kate Sylvester KITTELSON & ASSOCIATES, INC. Portland, OR Ingrid Potts Douglas Harwood David Gilmore Darren Torbic MIDWEST RESEARCH INSTITUTE Kansas City, MO Fred Hanscom TRANSPORTATION RESEARCH CORPORATION Markham, VA John McGill Delbert Stewart SYNECTICS, INC. St. Catharines, ON, Canada Subject Areas Planning and Administration 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. 2008 www.TRB.org

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NATIONAL COOPERATIVE HIGHWAY NCHRP REPORT 613 RESEARCH PROGRAM Systematic, well-designed research provides the most effective Project 3-74 approach to the solution of many problems facing highway ISSN 0077-5614 administrators and engineers. Often, highway problems are of local ISBN: 978-0-309-09935-6 interest and can best be studied by highway departments individually Library of Congress Control Number 2008927124 or in cooperation with their state universities and others. However, the © 2008 Transportation Research Board accelerating growth of highway transportation develops increasingly complex problems of wide interest to highway authorities. These problems are best studied through a coordinated program of COPYRIGHT PERMISSION cooperative research. Authors herein are responsible for the authenticity of their materials and for obtaining In recognition of these needs, the highway administrators of the written permissions from publishers or persons who own the copyright to any previously American Association of State Highway and Transportation Officials published or copyrighted material used herein. initiated in 1962 an objective national highway research program Cooperative Research Programs (CRP) grants permission to reproduce material in this employing modern scientific techniques. This program is supported on 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, a continuing basis by funds from participating member states of the FMCSA, FTA, or Transit Development Corporation endorsement of a particular product, Association and it receives the full cooperation and support of the method, or practice. It is expected that those reproducing the material in this document for Federal Highway Administration, United States Department of 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 Transportation. from CRP. The Transportation Research Board of the National Academies was requested by the Association to administer the research program because of the Board's recognized objectivity and understanding of NOTICE modern research practices. The Board is uniquely suited for this purpose as it maintains an extensive committee structure from which The project that is the subject of this report was a part of the National Cooperative Highway Research Program conducted by the Transportation Research Board with the approval of authorities on any highway transportation subject may be drawn; it the Governing Board of the National Research Council. Such approval reflects the possesses avenues of communications and cooperation with federal, Governing Board's judgment that the program concerned is of national importance and state and local governmental agencies, universities, and industry; its appropriate with respect to both the purposes and resources of the National Research Council. relationship to the National Research Council is an insurance of The members of the technical committee selected to monitor this project and to review this objectivity; it maintains a full-time research correlation staff of report were chosen for recognized scholarly competence and with due consideration for the specialists in highway transportation matters to bring the findings of balance of disciplines appropriate to the project. The opinions and conclusions expressed research directly to those who are in a position to use them. or implied are those of the research agency that performed the research, and, while they have been accepted as appropriate by the technical committee, they are not necessarily those of The program is developed on the basis of research needs identified the Transportation Research Board, the National Research Council, the American by chief administrators of the highway and transportation departments Association of State Highway and Transportation Officials, or the Federal Highway and by committees of AASHTO. Each year, specific areas of research Administration, U.S. Department of Transportation. needs to be included in the program are proposed to the National Each report is reviewed and accepted for publication by the technical committee according Research Council and the Board by the American Association of State to procedures established and monitored by the Transportation Research Board Executive Committee and the Governing Board of the National Research Council. Highway and Transportation Officials. Research projects to fulfill these needs are defined by the Board, and qualified research agencies are The Transportation Research Board of the National Academies, the National Research Council, the Federal Highway Administration, the American Association of State Highway selected from those that have submitted proposals. Administration and and Transportation Officials, and the individual states participating in the National surveillance of research contracts are the responsibilities of the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade Research Council and the Transportation Research Board. or manufacturers' names appear herein solely because they are considered essential to the object of this report. The needs for highway research are many, and the National Cooperative Highway Research Program can make significant contributions to the solution of 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. 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 at: http://www.national-academies.org/trb/bookstore Printed in the United States of America

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COOPERATIVE RESEARCH PROGRAMS CRP STAFF FOR NCHRP REPORT 613 Christopher W. Jenks, Director, Cooperative Research Programs Crawford F. Jencks, Deputy Director, Cooperative Research Programs Christopher J. Hedges, Senior Program Officer Eileen P. Delaney, Director of Publications Hilary Freer, Senior Editor Kami Cabral, Editor NCHRP PROJECT 3-74 PANEL Field of Traffic--Area of Operations and Control Mark C. Wilson, Florida DOT, Tallahassee, FL (Chair) Bryan K. Allery, Colorado DOT, Denver, CO Frank Corrao, III, Rhode Island DOT, Providence, RI Carlos Ibarra, Texas DOT, Atlanta, TX Steven S. Pasinski, Baker Engineering, Inc., Chicago, IL Nikiforos Stamatiadis, University of Kentucky, Lexington, KY J. Richard Young, Jr., PBS&J, Jackson, MS Joe Bared, FHWA Liaison Richard A. Cunard, TRB Liaison

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FOREWORD By Christopher J. Hedges Staff Officer Transportation Research Board This study evaluated the effectiveness of treatments to reduce vehicle speeds at high-speed intersections. The treatments included geometric design features as well as signage and pavement markings. In the first phase of research, potential treatments were evaluated based on their applicability, key features, speed effects, safety benefits, multimodal impacts, and maintenance issues. The most promising treatments were evaluated using field testing at 10 sites in Oregon, Washington, and Texas. The following guidelines are based on the research results and will provide highway planners and designers with an important new tool in their ongoing efforts to improve safety on our highway systems. Intersection crashes, a significant portion of total crashes nationwide, account for an average of 9,000 fatalities and 1.5 million injuries annually. Fatalities and severe injuries are more likely to occur in high-speed environments in rural and suburban areas. An recent international scanning tour focused on innovative safety practices in the planning, design, operation, and maintenance of signalized intersections. The scanning team visited several European countries and developed an implementation plan with five major recommenda- tions. One recommendation was to develop treatments that reduce speeds at the approaches to and through intersections. Under NCHRP Project 03-74, a research team led by Brian L. Ray of Kittelson & Associates, Inc., developed guidelines for selecting speed reduction treatments applicable to high-speed intersections. The first phase of the study consisted of a review of relevant literature and a survey of current practices of highway agencies across the country. The research team recommended three promising treatments for further eval- uation in the second phase of the study: rumble strips, transverse pavement markings, and dynamic warning signs. These treatments were evaluated using before-and-after field stud- ies at 10 sites in three states. Based on the results, the team developed guidelines illustrating sound practices for selecting appropriate speed-reduction treatments. These guidelines led the user through intersection pre-screening, treatment screening, and treatment implemen- tation considerations. The guidelines also include information about the effects of speed and the conditions that may contribute to undesirably high speeds at intersection approaches. A final report documenting the entire research effort is available as NCHRP Web-Only Document 124 on the TRB website at htp://trb.org/news/blurb_detail.asp? id-9101.

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PREFACE Managing speeds on all roadway types is of key interest to transportation professionals. Because of potential conflicts and the risk of collisions, speed management at intersections is of special interest. Research supporting the practice of managing high-speed intersections, however, is in its infancy. The treatments, and discussion of their application, in these guidelines are based on relatively limited research results from high-speed intersection loca- tions. We benefit from the intuitiveness of supplementing intersection testing results and applying what is known and documented about roadway segments and speed management. Under NCHRP Project 3-74, Kittelson & Associates, Inc., conducted testing on three speed reduction treatments, and these guidelines provide a foundation for future research that is needed to quantify the effects of each listed treatment. Future research should test the speed reduction qualities of the various treatments in a variety of applications. Further, additional information is needed to understand the possible benefits of combining treat- ments to maximize speed reduction opportunities. In addition to quality data on speed reduction, more must be learned and documented about speed's role in, and relationship to, intersection safety. These guidelines provide a substantial discussion about speed, the role it plays, and its impact on intersections. Roadway segments and intersections place different demands and risks on drivers. The discussion emphasizes the distinct relationship between roadway seg- ments and intersections. Engineering solutions for speed management should feature ele- ments that help drivers differentiate between the tasks needed in roadway segments versus those potentially needed at intersections. In some cases, speed reduction may not necessar- ily result in increased safety. Future studies may help professionals consider whether aiding drivers to be more alert and prepared to take needed actions at an intersection (versus along the upstream roadway segment) may be as valuable as actually reducing intersection speeds. As we collect volumes of speed reduction data for a variety of treatment types, perhaps future professionals will establish values for "speed modification factors" similar to the con- cept of "accident modification factors" being applied in highway safety manual initiatives. With a sufficient database of speed reduction information for a variety of treatments in numerous applications, future users of updated guidelines may enjoy the benefits of predic- tive tools to consider the tradeoffs and benefits of various speed management treatments in a wide range of high-speed intersection environments.

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CONTENTS 1 Summary 3 Section 1 Introduction 3 1.1 Intended Users 3 1.2 Purpose of Guidelines 3 1.3 Scope of Guidelines 4 1.4 Report Organization 5 Section 2 Speed Considerations 5 2.1 Overview 5 2.2 Intersection/Segment Relationship 7 2.3 Designing for Appropriate Speeds 7 2.4 Factors Influenced by Speed 10 2.5 Factors that Affect Speed 12 2.6 Conditions Potentially Sensitive to Speed 14 2.7 Summary 15 Section 3 Selecting an Appropriate Treatment 15 3.1 Introduction 16 3.2 Determining the Need for a Treatment 16 3.3 Treatment Selection Process 20 3.4 Combining Treatments 21 3.5 Treatment Considerations 27 3.6 Treatment Evaluation 28 3.7 Summary 29 Section 4 Treatment Descriptions 29 4.1 Overview 30 4.2 Dynamic Warning Signs 33 4.3 Transverse Pavement Markings 36 4.4 Transverse Rumble Strips 39 4.5 Longitudinal Rumble Strips 42 4.6 Wider Longitudinal Pavement Markings 44 4.7 Roundabouts 47 4.8 Approach Curvature 49 4.9 Splitter Islands 52 4.10 Speed Tables and Plateaus 54 4.11 Reduced Lane Width 57 4.12 Visible Shoulder Treatments 58 4.13 Roadside Design Features 61 4.14 Summary 62 References

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65 Appendix A Treatment Implementation Process Framework 68 Appendix B Case Studies 95 Appendix C Testing Results 98 Appendix D Supplemental References