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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 750 Strategic Issues Facing Transportation Volume 6: The Effects of Socio-Demographics on Future Travel Demand Johanna P. Zmud RAND CoRpoRAtioN Arlington, VA Vincent P. Barabba Capitola, CA Mark Bradley ResouRCe systems GRoup, iNC. Santa Barbara, CA J. Richard Kuzmyak ReNAissANCe plANNiNG GRoup Arlington, VA Mia Zmud metRopiA Austin, TX David Orrell systems FoReCAstiNG Toronto, ON Subscriber Categories Administration and Management ⢠Planning and Forecasting ⢠Society 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 Boardâs 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 750, VOLUME 6 Project 20-83(6) ISSN 0077-5614 ISBN 978-0-309-28420-2 Library of Congress Control Number 2013932452 © 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. Front cover images from the top: © G. Blakeley/iStockphoto; © 2014 California Depart- ment of Transportation; © Isaac L. Koval/iStockphoto; © 2009 Kimberly Fisher; © San Francisco Municipal Transportation Agency. 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 manufacturersâ names appear herein solely because they are considered essential to the object of the report. Front cover: image used in second circle from the top: © John Gillespie, All full on the Fran- kentrain: Rush hour lasted all day in New York as limited service on the subway resumed. Used under Creative Commons license (CC BY-SA 2.0); fifth circle from top: © Myleen Hollero, San Francisco Bicycle Coalition, Bike to Work Day. Used under Creative Commons license (CC BY-NC-ND 2.0).
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 Academyâs 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 Boardâs 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 750, VOLUME 6 Christopher W. Jenks, Director, Cooperative Research Programs Christopher J. Hedges, Manager, National Cooperative Highway Research Program Shelia A. Moore, Program Associate Eileen P. Delaney, Director of Publications Margaret B. Hagood, Editor NCHRP PROJECT 20-83(6) PANEL Area of Special Projects Gary A. Frederick, New York State DOT, Albany, NY (Chair) Arun Chatterjee, University of Tennessee - Knoxville, Knoxville, TN Mark W. Horner, Florida State University, Tallahassee, FL Judy Lang, San Luis Obispo, CA Jerome M. Lutin, Jerome M. Lutin, PhD, LLC, Monmouth Junction, NJ Lizbeth L. Martin-Mahar, Washington State DOT, Olympia, WA Kyle Mote, Georgia DOT, Atlanta, GA Keith M. Sherman, Petersburg, IL Duncan F. Stewart, University of Texas - Austin, Center for Transportation Research, Austin, TX Sarah Sun, FHWA Liaison Kimberly Fisher, TRB Liaison AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under NCHRP Project 20-83(06) by NuStats, LLC. Dr. Johanna P. Zmud, RAND Transportation, Space, and Technology Program at the RAND Corporation, was the principal investigator and lead author of this report; Mia Zmud of Metropia was the project director for the research and a co-author of the report. Other co-authors of the report include Vincent P. Barabba, consultant; Mark Bradley, Resource Systems Group, Inc.; and J. Richard Kuzmyak, Renaissance Planning Group. The other members of the research team are Dr. Carlos Arce, Ethnifacts; Leo Estrada, UCLA; Keith Lawton, Keith Lawton Consulting, LLC; David Orrell, Smith School of Enterprise and the Environment; and Frank Spielberg, consultant. The authors would also like to acknowledge participants in the Workshop on Strategic Assumptions Surfacing and Testing that was held March 8â9, 2011, at the RAND Corporation in Arlington, Virginia: Wade Bryant, Advanced Design Studios of General Motors; Arun Chatterjee, University of Tennessee in Knoxville; Judy Lang, California Department of Transportation; Jerry Lutin, consultant; Kate Piacente, RAND Corporation; Alan Pisarski, consultant; Rolf Smith, Federal Highway Administration; Sudeshna Sen, Merkle; Chris Sinclair, Renaissance Planning Group; Duncan Stewart, consultant; Sarah Sun, Fed- eral Highway Administration; Mary Lynn Tischer, Federal Highway Administration; and Lisa Whalen, General Motors Corporation. The research team also acknowledges Ana Arce Casas for her assistance with the development of figures and tables and production of this report, and Sue Foster, NuStats, LLC for fiscal oversight of the contract.
This report presents the results of research on how socio-demographic changes over the next 30 to 50 years will impact travel demand at the regional level. It is accompanied by a software tool, Impacts 2050, to support transportation agencies in their long-term planning activities to enhance decision making. This report will help transportation decision makers understand how the population may change over time, how socio-demographic changes will affect the ways people travel, and the kinds of transportation modes and infrastructure that will be needed. Major trends affecting the future of the United States and the world will dramatically reshape transportation priorities and needs. The American Association of State High- way and Transportation Officials established the NCHRP Project 20-83 research series to examine global and domestic long-range strategic issues and their implications for departments of transportation (DOTs) to help prepare the DOTs for the challenges and benefits created by these trends. NCHRP Report 750: Strategic Issues Facing Transporta- tion, Volume 6: The Effects of Socio-Demographics on Future Travel Demand is the sixth report in this series. The profile of America is expected to change substantially over the next 40 years. According to the U.S. Census Bureau, current trends suggest that the U.S. population is anticipated to increase to 438 million by 2050, more than a 40% increase from the 2008 population of 304 million. This population will be more ethnically diverse; a significant percentage of the projected population increase is attributed to immigration. The popula- tion also will be substantially older; it is estimated that more than 20% of the U.S. popula- tion will be 65 years or older by 2050, compared to 12.6% currently. The sizeable increase in population will create the need for more housing, employment, and services, which may lead to substantial impacts on travel patterns and demands. It has been estimated that the majority of the U.S. population will live in mega-regions, with more than 80% of the population in metropolitan, urban, and suburban areas. Baby Boomers are expected to choose a âsoft retirementâ and continue to work part-time beyond retirement age. Young people coming out of full-time education may increasingly choose to enter what they consider temporary, short-term jobs, which they use to finance international travel, volunteering in nonprofit or arts-related careers, and/or continued education. Changes in family structure, participation of women in the labor market, incomes, lifestyles, and social expectations may also occur. Under NCHRP 20-83(06) a research team led by the RAND Corporation looked at how socio-demographic issues over the next 30 to 50 years are likely to change the popula- tionâs transportation needs, travel patterns, and expectations regarding mobility. F O R E W O R D By Christopher J. Hedges Staff Officer Transportation Research Board
The research approach involved identifying a number of plausible future scenarios and development of a systems dynamic model that simulates the demographic evolu- tion of a regional population starting from a baseline of the 2000 census and spanning a period of 50 years. The four future scenarios were developed using a Strategic Assump- tions Surfacing and Testing (SAST) technique and include the following: (1) Momentum: gradual change without radical shifts; (2) Technology Triumphs: technology solves many present-day problems; (3) Global Chaos: a collapse in globalism and sustainability, and (4) Gentle Footprint: a widespread shift to low-impact living. The model does not predict which scenario is most likely; instead it predicts how travel demand will change under each of the five sectors: socio-demographics, travel behavior, land use, employment, and transportation supply. The Impacts 2050 tool enables modeling of changes in these sectors due to socio-demographic changes, the interplay between sectors, and external factors such as attitudes and technology. The accompanying CD contains Impacts 2050, the userâs guide, a PowerPoint presentation about the research, and the research brief.
1 Chapter 1 Introduction 1 1.1 Research Overview and Objectives 2 1.2 Organization of the Report 4 Chapter 2 Long-Range Planning in an Uncertain World 4 2.1 Uncertainty in Forecasts 5 2.2 Accuracy of Travel Demand Forecasts 6 2.3 Handling Uncertainty 7 2.4 Improved Long-Range Transportation Planning 9 Chapter 3 Key Trends, Drivers, and Projected Impact on Travel Behavior 9 3.1 Eight Socio-Demographic Trends 23 Chapter 4 Study Approach: Scenario Planning and System Dynamics Model 23 4.1 Rationale for Approach 25 4.2 Scenario Planning Approach 27 4.3 SD Modeling Approach 30 Chapter 5 Future Scenarios: Process and Narratives 30 5.1 Scenario Development and Assumption Testing 35 5.2 Scenario Descriptions 38 Chapter 6 Scenario Planning Tool: Impacts 2050 38 6.1 Overview of the SD Model 41 6.2 Scenarios in Impacts 2050 42 6.3 Regional Settings for Model Testing 44 6.4 Running Impacts 2050 for the Test Regions 52 Chapter 7 Key Indicators and Monitoring Approach 52 7.1 Defining Key Indicators 53 7.2 Driving Forces in the Scenarios 56 7.3 Monitoring Key Indicators or Early Warning Signs 57 7.4 Identifying Indicators Using Impacts 2050 57 7.5 Monitoring the Future with Impacts 2050 59 Chapter 8 Relevance and Value of Impacts 2050 to Transportation Agencies 60 8.1 Demands of the Long-Range Planning Process 62 8.2 Value and Potential Use of Impacts 2050 65 8.3 Value of Prepackaged Scenarios 67 8.4 Strategic Responses 69 8.5 Challenges Facing State DOTs and MPOs 70 8.6 Response Mechanisms for Meeting an Uncertain Future C O N T E N T S
72 Chapter 9 Opportunities for Improved Decision Making 72 9.1 Addressing the Dynamic Complexity of the 21st Century 73 9.2 Changing Oneâs Mindset to Handle Complex and Dynamic Problems 74 9.3 Reinventing the Model to Meet the Requirements of an Uncertain Environment 75 9.4 Doing Better 75 9.5 Getting the Research into Practice 77 References 81 Appendix A Scenario Narratives 91 Appendix B Impacts 2050 Model Structure Documentation 113 Appendix C Statistical Output 115 Appendix D Method and Findings from Demonstrating and Testing Impacts 2050 120 Appendix E Tool for Identifying Driving Forces in the Scenarios 122 Appendix F Final Research Brief for NCHRP Report 750, Volume 6 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.