Analytical Travel Forecasting Approaches for Project-Level Planning and Design (2014)

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

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 765 Analytical Travel Forecasting Approaches for Project-Level Planning and Design CDM Smith Cambridge, MA Alan Horowitz Milwaukee, WI Tom Creasey Lexington, KY Ram Pendyala Phoenix, AZ Mei Chen Lexington, KY Subscriber Categories Highways • Planning and Forecasting • Operations and Traffic Management TRANSPORTAT ION RESEARCH BOARD WASHINGTON, D.C. 2014 www.TRB.org 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. 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. 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 NCHRP REPORT 765 Project 08-83 ISSN 0077-5614 ISBN 978-0-309-28404-2 Library of Congress Control Number 2014940220 © 2014 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, FMCSA, FTA, or Transit Development Corporation 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. NOTICE 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 the Governing Board of the National Research Council. The members of the technical panel selected to monitor this project and to review this report were chosen for their special competencies and with regard for appropriate balance. 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 Governing Board of the National Research Council. 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 Research Council, or the program sponsors. The Transportation Research Board of the National Academies, the National Research Council, and the sponsors of 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 the report.

The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars 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 technical matters. Dr. Ralph J. Cicerone is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy 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 achievements of engineers. Dr. C. D. Mote, Jr., 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 Academy, 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 Academies and the Institute of Medicine. Dr. Ralph J. Cicerone and Dr. C. D. Mote, Jr., are chair and vice chair, respectively, of the National Research Council. The Transportation Research Board is one of six major divisions of the National Research Council. The mission of the Transporta- tion Research Board is to provide leadership in transportation innovation and progress through research and information exchange, conducted within a setting that is objective, interdisciplinary, and multimodal. The Board’s varied activities annually engage about 7,000 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 individu- als interested in the development of transportation. www.TRB.org www.national-academies.org

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 CRP STAFF FOR NCHRP REPORT 765 Christopher W. Jenks, Director, Cooperative Research Programs Christopher Hedges, Manager, National Cooperative Highway Research Program Nanda Srinivasan, Senior Program Officer Charlotte Thomas, Senior Program Assistant Eileen P. Delaney, Director of Publications Ellen M. Chafee, Editor NCHRP PROJECT 08-83 PANEL Field of Transportation Planning—Area of Forecasting Michael S. Bruff, North Carolina DOT, Raleigh, NC (Chair) Subrat Mahapatra, Maryland State Highway Administration, Baltimore, MD Philip Ben Cox, California DOT, Oakland, CA Dan Lamers, North Central Texas Council of Governments, Arlington, TX Derek Miura, FHWA, Lakewood, CO Eric Pihl, FHWA, Lakewood, CO Jeffrey A. Shelton, Texas A & M University, El Paso, TX Kermit Wies, Chicago Metropolitan Agency for Planning, Chicago, IL Robert M. Winick, Motion Maps LLC, Rockville, MD Sarah Sun, FHWA Liaison Matthew Hardy, AASHTO Liaison Kimberly Fisher, TRB Liaison

F O R E W O R D By Nanda Srinivasan Staff Officer Transportation Research Board This report is an update to NCHRP Report 255: Highway Traffic Data for Urbanized Area Project Planning and Design and describes methods, data sources, and procedures for pro- ducing travel forecasts for highway project-level analyses. The report provides an evaluation of currently used methods and tools. The report also includes appropriate information sources and system-level methods (ranging from readily available practices to advanced practices) to address a variety of project development purposes, needs, and impacts. The report is intended to be used by transportation planning, operations, and project devel- opment staff to better support planning, design, and operations recommendations. The report is accompanied by a CD-ROM providing spreadsheet tools developed for project- level analyses as well as appendices from the contractor’s final report. In 1982, TRB published NCHRP Report 255: Highway Traffic Data for Urbanized Area Project Planning and Design. This report compiled techniques used in urban areas to bridge the gap between system-level and project-level analyses. In 1982, there was an emphasis on new and expanded highway facilities, but today the focus has broadened to include travel demand management strategies and operational efficiency strategies. Spatial and temporal aspects of congestion are difficult to capture at the precision necessary for project-level decision-making with conventional traffic forecasting techniques. For heavily congested urban study areas and corridors, it is important to capture the effects of residual demand and peak spreading at a project level. Since 1982, there have been many improvements in travel models; however, relatively few efforts have been made to meet post-processing needs for project-level analysis. There was a need to evaluate currently used post-processors and refinement methods and to determine how to best communicate the results so that stakeholders have a sufficient degree of understanding and acceptance. Improvements in methods were needed to provide plausible and defensible forecasts to support planning and highway project development. The objective of this research was to evaluate and describe currently used methods, data sources, and procedures for producing travel forecasts for highway project-level analysis. The research was performed by CDM Smith in association with Alan Horo witz of the University of Wisconsin at Milwaukee, Tom Creasey of Stantec, Ram Pendyala of Arizona State University, and Mei Chen of the University of Kentucky. Information was gathered via literature review, a national survey, interviews with practitioners, focus groups, and case studies collected from metropolitan planning organizations and state departments of transportation.

C O N T E N T S P A R T 1 Background 3 Chapter 1 Introduction 3 1.1 What Are Projects? 3 1.2 Context of NCHRP Report 255 4 1.3 Traffic Forecasting Guidelines 4 1.4 Chapter-by-Chapter Review of NCHRP Report 255 4 1.5 Traffic Forecasting State of the Practice 7 1.6 Report Organization 8 1.7 CRP-CD-143 9 Chapter 2 Overview of the Fundamentals of Traffic Forecasting 9 2.1 Traffic Forecasting Data and Parameters 11 2.2 Traffic Forecasting Tools 11 2.3 Measures of Effectiveness 15 2.4 Essential Bookshelf 22 Chapter 3 Overview of Traffic Forecasting Tools and Methodologies 22 3.1 The Travel Forecasting Model Ideal 24 3.2 State of the Practice of Travel Forecasting Models 43 3.3 State of the Practice of Data Inputs for Travel Forecasting Models 50 3.4 State of the Practice of Outputs for Travel Forecasting Models 52 3.5 Defaults versus Locally Specific Parameters 53 3.6 Other Traffic Forecasting Tools and Methodologies P A R T 2 Guidelines 59 Chapter 4 The Project-Level Forecasting Process 59 4.1 Traffic Forecasting Context—Management Perspective 66 4.2 Traffic Forecasting Steps—Analyst Perspective 74 4.3 Role of Judgment 76 4.4 Forecast Accuracy 82 4.5 Traffic Forecasting Rules of Thumb 84 Chapter 5 Working with a Travel Model 84 5.1 Understanding the Model 85 5.2 Project-Level Forecast Validation 87 5.3 Understanding Variability in Speed and Volume Data 88 5.4 Fixing Issues in Input or Validation Data 97 5.5 Understanding Travel Model Outputs 102 5.6 Handling Outliers in Model Outputs 104 5.7 Computation Technology Issues and Opportunities

106 Chapter 6 Model Output Refinements 107 6.1 Screenline Refinement with Base Volumes 113 6.2 Factoring Procedure—Ratio Method 114 6.3 Factoring Procedure—Difference Method 115 6.4 Iterative Procedure—Directional Method 122 6.5 Iterative Procedure—Non-Directional Method 128 6.6 “T” Intersection Procedure—Non-Directional Method 129 6.7 “T” Intersection Procedure—Directional Method 130 6.8 Refining Directional Splits From Travel Models 132 6.9 Balancing Volumes in a Corridor 134 6.10 Travel Time Reliability 137 6.11 Model Refinement with Origin-Destination Table Estimation 141 6.12 Refinement with Origin-Destination Table Estimation, Small and Wide Areas 145 Chapter 7 Refining the Spatial Detail of Traffic Models 145 7.1 Method: Subarea Focusing, Custom Networks, or Customization of a Region-Wide Network 150 7.2 Windowing to Forecast Traffic for Small Areas 155 7.3 Method: Multiresolution Modeling 162 7.4 Method: Integrating Statewide, Regional, and Local Travel Models 168 7.5 Method: External-to-External Station Origin-Destination Table Refinement 174 Chapter 8 Improving the Temporal Accuracy of Traffic Forecasts 174 8.1 Method: Activity-Based Travel Demand Model Systems 182 8.2 Method: Dynamic Traffic Assignment 188 8.3 Peak Spreading 198 8.4 Method: Pre-Assignment Time-of-Day Factoring 202 8.5 Method: Post-Assignment Time-of-Day Factoring 210 8.6 Day-of-the-Week Factors and Monthly Factors 210 8.7 Vehicle Class Considerations 223 Chapter 9 Traffic Forecasting Methods for Special Purpose Applications 223 9.1 Basic Highway Design Traffic Forecasting Products 223 9.2 Interpolation of Traffic Forecasts 224 9.3 Improving Vehicle Mix Accuracy of Forecasts or Data Extrapolations 227 9.4 Special Needs of Equivalent Single Axle Loads 232 9.5 Special Needs of Benefit-Cost Analysis 234 9.6 Special Needs of Toll/Revenue Forecasts 235 9.7 Special Needs of Work Zones: Diversion and Delay Forecasts 237 9.8 Special Needs of Environmental Justice 238 9.9 Special Needs of Traffic Impact Studies 239 Chapter 10 Tools Other Than Travel Models 239 10.1 Method: Time Series of Traffic Volume Data 245 10.2 Sketch-Planning Technique: Manual Gravity Model 248 10.3 Elasticity Methods 252 10.4 Using the Highway Capacity Manual in Project-Level Traffic Forecasting 257 10.5 Stitching a Model Together 258 10.6 Simplified Highway Forecasting Tool

260 Chapter 11 Case Studies 260 11.1 Case Study #1—Suburban Arterial 270 11.2 Case Study #2—Network Window 274 11.3 Case Study #3—Small City 282 11.4 Case Study #4—Activity-Based Model Application for Project-Level Traffic Forecasting/Analysis: HOV to HOT Lane Conversion 287 11.5 Case Study #5—Time-Series Analysis of the Blue Water Bridge 296 11.6 Case Study #6—Blending a Regional Travel Forecasting Model with a Traffic Microsimulation 300 References and Bibliography 305 Abbreviations, Acronyms, and Initialisms Note: Many of the photographs, figures, and tables in this report have been converted from color to grayscale for printing. The electronic version of the report (posted on the Web at www.trb.org) retains the color versions.