Default Values for Highway Capacity and Level of Service Analyses (2008)

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TRANSPORTAT ION RESEARCH BOARD WASHINGTON, D.C. 2008 www.TRB.org 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 REPORT 599 Subject Areas Planning and Administration Default Values for Highway Capacity and Level of Service Analyses John D. Zegeer Mark Vandehey Miranda Blogg Khang Nguyen Michael Ereti KITTELSON & ASSOCIATES, INC. Fort Lauderdale, FL Research sponsored by the American Association of State Highway and Transportation Officials in cooperation with the Federal Highway Administration

NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed research provides the most effective approach to the solution of many problems facing highway administrators and engineers. Often, highway problems are of local interest and can best be studied by highway departments individually or in cooperation with their state universities and others. However, the 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 cooperative research. 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 Department of Transportation. 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 modern research practices. The Board is uniquely suited for this purpose as it maintains an extensive committee structure from which authorities on any highway transportation subject may be drawn; it possesses avenues of communications and cooperation with federal, state and local governmental agencies, universities, and industry; its relationship to the National Research Council is an insurance of objectivity; it maintains a full-time research correlation staff of specialists in highway transportation matters to bring the findings of research directly to those who are in a position to use them. The program is developed on the basis of research needs identified by chief administrators of the highway and transportation departments and by committees of AASHTO. Each year, specific areas of research needs to be included in the program are proposed to the National Research Council and the Board by the American Association of State Highway and Transportation Officials. 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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 NCHRP REPORT 599 Project 3-82 ISSN 0077-5614 ISBN: 978-0-309-09931-8 Library of Congress Control Number 2008925081 © 2008 Transportation Research Board COPYRIGHT PERMISSION 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. 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The members of the technical committee selected to monitor this project and to review this report were chosen for recognized scholarly competence and with due consideration for the balance of disciplines appropriate to the project. The opinions and conclusions expressed 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 Transportation Research Board, the National Research Council, the American Association of State Highway and Transportation Officials, or the Federal Highway Administration, U.S. Department of Transportation. Each report is reviewed and accepted for publication by the technical committee according to procedures established and monitored by the Transportation Research Board Executive Committee and the Governing Board of the National Research Council. 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CRP STAFF FOR NCHRP REPORT 599 Christopher W. Jenks, Director, Cooperative Research Programs Crawford F. Jencks, Deputy Director, Cooperative Research Programs B. Ray Derr, Senior Program Officer Eileen P. Delaney, Director of Publications Kami Cabral, Editor NCHRP PROJECT 3-82 Field of Traffic—Area of Operations and Control Robert W. Bryson, City of Milwaukee, Milwaukee, WI (Chair) Martin Guttenplan, Florida DOT, Tallahassee, FL Montasir M. Abbas, Virginia Polytechnic Institute and State University, Blacksburg, VA Thomas W. “Bill” Brockenbrough, Jr., Delaware DOT, Dover, DE F. Thomas Creasey, American Consulting Engineers, PLC, Lexington, KY Jeffery L. Memmott, Bureau of Transportation Statistics, Washington, DC Narasimha Murthy, Murthy Transportation Consultants, Inc., Fullerton, CA Douglas Norval, Oregon DOT, Salem, OR Roger L. Russell, Charleston, WV Zong Z. Tian, University of Nevada - Reno, Reno, NV John Halkias, FHWA Liaison Richard A. Cunard, TRB Liaison AUTHOR ACKNOWLEDGMENTS The Highway Capacity Manual Default Value Guidebook was developed under NCHRP Project 3-82. The NCHRP Project 3-82 team consisted of Kittelson & Associates, Inc. (prime contractor), assisted by Dr. James Bonneson (Texas Transportation Institute) and Dr. Fred Hall (McMaster University). John D. Zegeer, P.E., PTOE, Senior Principal, Kittelson & Associates, Inc., was the principal investiga- tor. Additional Kittelson & Associates, Inc., staff who played key roles in the development of this Guide- book included Miranda Blogg, Khang Nguyen, Michael Ereti, and Mark Vandehey. Additional assistance in the data summary and analysis activities for various input parameters was provided by other Kittelson staff, including Cade Braud, Joey Bansen, Justin Bansen, Thuha Lyew, Gorken Mimioglu, Alek Pochowski, and Ning Zou. Terry Raddeman provided GIS graphical support and analysis of metropolitan area pop- ulations. Beverley King provided word processing and editorial assistance. Finally, the project team would like to express its appreciation for the dedicated work of the NCHRP Project 3-82 panel. The majority of the panel members have been involved in the review of interim mate- rials and oversight of the findings throughout the project. The panel provided many thoughtful comments that have helped shape the current form of the Guidebook. The guidance provided by the NCHRP Pro- gram Officer, B. Ray Derr, is also greatly appreciated. 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

Based on the assembly of an extensive set of field data from across the United States, this report presents valuable information on the appropriate selection of default values when analyzing highway capacity and level of service. The report will be useful to planners, geo- metric designers, and traffic engineers who do not have ready access to field data for an analysis. The report also describes how to prepare service volume tables, which can be a use- ful sketch planning technique. The Year 2000 Highway Capacity Manual (HCM 2000) is the most extensively referenced document on highway capacity and quality-of-service computations in the United States. While the HCM 2000 focuses on providing state-of-the-art methodologies for operational analyses, it is also used in planning and preliminary engineering applications. To assist engineers and planners in applying HCM methodologies, the HCM 2000 includes default values for many of the more difficult-to-obtain input parameters and vari- ables. The HCM 2000 states: “A default value is a representative value that may be appro- priate in the absence of local data.” As a result of insufficient field data, the HCM 2000 recommends only a single default value for many key data items, inadequately reflecting the variety of traffic and facility conditions across the United States. Because of limited resources or inexperience, analysts often use these default values inappropriately. Under NCHRP Project 3-82, Kittelson & Associates, Inc., and their subcontractors reviewed all of the input values in the HCM to determine how sensitive the analysis method- ologies are to them and the difficulty of obtaining non-default input values. They then assembled field data from various sources on the critical values. A statistical analysis of the field data was performed to develop guidance on the most appropriate default values to use. These recommended default values could be used in place of the default values provided in HCM 2000. By B. Ray Derr Staff Officer Transportation Research Board F O R E W O R D

1 Summary 1 Purpose of the Guidebook 2 Findings 3 Recommendations 9 Use of Service Volume Tables 11 Chapter 1 Introduction 13 Chapter 2 Current Planning Practices 13 History of HCM 2000 14 HCM 2000 Guidance on the Use of Default Values 17 HCM Definitions 18 Inventory of Default Values 30 User Survey Results 31 Chapter 3 Recommended Default Values 31 Defining Default Values by Category 34 Data Sources and Calculation Methodology 35 %HV for Uninterrupted Flow Facilities 37 PHFs for Uninterrupted Flow Facilities 43 %HV for Interrupted Flow Facilities 47 PHFs for Interrupted Flow Facilities 51 Base Saturation Flow Rates for Signalized Intersections 53 Lane Utilization for Through Lanes at Signalized Intersections 55 Chapter 4 Guidance for Selecting Defaults 55 Pedestrian Walking Speeds and Start-up Times at Signalized Intersections 58 Interchange Ramp Terminals 62 Driver Population Factors on Freeways 65 Signal Density on Urban Streets 66 Free-Flow Speed on Urban Streets 73 Saturation Flow Rates and Lane Utilization Factors for Dual and Triple Left-Turn Lanes 77 Chapter 5 Guidance for Preparing Service Volume Tables 77 Sample Service Volume Tables 79 Sensitivity Analysis 83 Appendix A Sensitivity Analysis 119 Appendix B Lane Utilization Adjustment Factors for Interchange Ramp Terminals C O N T E N T S