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NATIONAL
NCHRP REPORT 588
COOPERATIVE
HIGHWAY
RESEARCH
PROGRAM
A Guidebook for Using American
Community Survey Data for
Transportation Planning
OCR for page R1
TRANSPORTATION RESEARCH BOARD 2007 EXECUTIVE COMMITTEE*
OFFICERS
CHAIR: Linda S. Watson, CEO, LYNXCentral Florida Regional Transportation Authority, Orlando
VICE CHAIR: Debra L. Miller, Secretary, Kansas DOT, Topeka
EXECUTIVE DIRECTOR: Robert E. Skinner, Jr., Transportation Research Board
MEMBERS
J. Barry Barker, Executive Director, Transit Authority of River City, Louisville, KY
Michael W. Behrens, Executive Director, Texas DOT, Austin
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, Vice President, Customer Service, Norfolk Southern Corporation and Subsidiaries, Atlanta, GA
Anne P. Canby, President, Surface Transportation Policy Partnership, Washington, DC
Nicholas J. Garber, Henry L. Kinnier Professor, Department of Civil Engineering, University of Virginia, Charlottesville
Angela Gittens, Vice President, Airport Business Services, HNTB Corporation, Miami, FL
Susan Hanson, Landry University Professor of Geography, Graduate School of Geography, Clark University, Worcester, MA
Adib K. Kanafani, Cahill Professor of Civil Engineering, University of California, Berkeley
Harold E. Linnenkohl, Commissioner, Georgia DOT, Atlanta
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
John R. Njord, Executive Director, Utah DOT, Salt Lake City
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., Senior Professor, Washington University, St. Louis, MO
C. Michael Walton, Ernest H. Cockrell Centennial Chair in Engineering, University of Texas, Austin
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
Thomas J. Barrett (Vice Adm., U.S. Coast Guard, ret.), Pipeline and Hazardous Materials Safety Administrator, U.S.DOT
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
J. Richard Capka, Federal Highway Administrator, U.S.DOT
Sean T. Connaughton, Maritime Administrator, U.S.DOT
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
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
Jeffrey N. Shane, Under Secretary for Policy, U.S.DOT
James S. Simpson, Federal Transit Administrator, U.S.DOT
Carl A. Strock (Lt. Gen., U.S. Army), Chief of Engineers and Commanding General, U.S. Army Corps of Engineers, Washington, DC
Robert A. Sturgell, Acting Administrator, Federal Aviation Administration, U.S.DOT
*Membership as of October 2007.
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NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM
NCHRP REPORT 588
A Guidebook for Using American
Community Survey Data for
Transportation Planning
Cambridge Systematics, Inc.
Cambridge, MA
NuStats
Austin, TX
Nancy McGuckin
Washington, DC
Earl Ruiter
Franklin, NH
Subject Areas
Planning and Administration · Operations and Safety · Aviation · Public Transit
Rail · Freight Transportation · Marine Transportation
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.
2007
www.TRB.org
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NATIONAL COOPERATIVE HIGHWAY NCHRP REPORT 588
RESEARCH PROGRAM
Systematic, well-designed research provides the most effective Project 8-48
approach to the solution of many problems facing highway ISSN 0077-5614
administrators and engineers. Often, highway problems are of local ISBN: 978-0-309-09911-0
interest and can best be studied by highway departments individually Library of Congress Control Number 2007908482
or in cooperation with their state universities and others. However, the © 2007 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 588
Christopher W. Jenks, Director, Cooperative Research Programs
Crawford F. Jencks, Deputy Director, Cooperative Research Programs
Ronald D. McCready, Senior Program Officer
Eileen P. Delaney, Director of Publications
NCHRP PROJECT 8-48 PANEL
Field of Transportation Planning--Area of Forecasting
Alan E. Pisarski, Falls Church, VA (Chair)
Cheryl R. Ball, Missouri DOT
Ed J. Christopher, Federal Highway Administration
Nathan S. Erlbaum, New York State DOT
Kara M. Kockelman, University of TexasAustin
Jonette R. Kreideweis, Minnesota DOT
Emily Parkany, Mitretek Systems, Inc., Washington, DC
Charles L. Purvis, Metropolitan Transportation CommissionOakland, CA
Robert Sicko, Mirai Associates, Kirkland, WA
Alice T. Wiggins-Tolbert, Parsons Brinckerhoff, Los Angeles, CA
Elaine R. Murakami, FHWA Liaison
David H. Clawson, AASHTO Liaison
Lynn Weidman, U.S. Census Bureau Liaison
Pheny Weidman, RITA Liaison
Kimberly Fisher, TRB Liaison
Tom Palmerlee, TRB Liaison
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FOREWORD
By Kimberly M. Fisher
Staff Officer
Transportation Research Board
Census data have long played a central role in transportation planning and analyses. In
particular, the planning community has made extensive use of the Census Long Form. Begin-
ning with this decade, the Census Bureau's American Community Survey (ACS) will replace
the Census Long Form. This practitioner's guidebook focuses on incorporating ACS data
into the transportation planning processes at national, state, metropolitan, and local levels.
The guidebook evaluates ACS data and products and demonstrates their uses within a wide
range of transportation planning applications. Transportation planners, travel demand fore-
casters, and others that conduct population and demographic analyses will find this report
of significant use. As these transportation professionals struggle to use the limited local data
and changing national data as the basis for transportation plans, the report will provide meth-
ods and tools to improve the connection between planning and programming.
Transportation planners have relied heavily on the decennial Census "long form" data
because these data provided detailed demographic characteristics along with journey-to-
work data for small units of geography such as census tracts or traffic analysis zones (TAZs).
It is the long form that provided data for the Census Transportation Planning Package
(CTPP), the mostly widely used database for transportation planning. The U.S. Census
Bureau is replacing the long form with a continuous data collection program called the
American Community Survey (ACS). The transportation planning community needs to
know how to use this new source of data in applications such as long-range planning and
forecasting, environmental and project analysis, and descriptive statistics. The ACS differs
from the decennial Census in many ways, especially as it represents a change from data col-
lected at a single point-in-time (April 1, 2000) to data collected continuously throughout
the year and summarized annually for large geographic units. Data for TAZs or tracts will
be available based on a moving average of data accumulated over a 5-year period.
The ACS provides new opportunities and challenges for assessing transportation trends.
Guidance is needed on the application, interpretation, and presentation of these new data
for transportation planning practitioners and policymakers. This guidebook identifies the
key issues that will face transportation planners as they use ACS data to complete analyses
that have historically been performed with the decennial Census Long Form data and out-
lines potential new transportation planning analyses that transportation planners may
conduct with the ACS.
This research effort was conducted by Cambridge Systematics, Inc. along with NuStats,
Nancy McGuckin, and Earl Ruiter under NCHRP Project 8-48.
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CONTENTS
1 Chapter 1 Introduction
1 1.1 Overview of the American Community Survey
2 1.2 Some Important Implications of ACS for Data Users
3 1.3 Purpose and Organization of this Guidebook
4 1.4 Additional Information Sources for an Introduction to ACS
6 Chapter 2 American Community Survey
6 2.1 ACS Implementation
18 2.2 Additional Information Sources on ACS Implementation
22 Chapter 3 Obtaining ACS Data
22 3.1 ACS Data Products
30 3.2 Additional Information Sources for Obtaining ACS Data
31 Chapter 4 Using ACS Data
31 4.1 Accuracy of ACS Data
37 4.2 Data Accumulation over Time and Geography
44 4.3 Data Disclosure Limitations
48 4.4 Understanding, Working with, and Reporting Sample Data
53 4.5 Comparison of ACS Estimates to Census
65 4.6 Implications of ACS Data Release Frequency
73 Chapter 5 Policy Planning and Other Descriptive Analyses
Using ACS Data
73 5.1 Descriptive Analyses
76 5.2 Benefits and Limitations of ACS for Descriptive Analyses
76 5.3 Descriptive Analysis Case Studies
101 5.4 Other Specific Uses of Census Data for Descriptive Analyses
102 Chapter 6 Trend Analyses Using ACS Data
102 6.1 Trend Analysis
104 6.2 Benefits and Limitations of ACS for Trend Analysis
104 6.3 Trend Analysis Case Study
111 6.4 Conclusions from the Case Study
114 6.5 Specific Uses of Census Data for Trend Analyses
117 Chapter 7 Transportation Market Analyses Using ACS Data
117 7.1 Transportation Market Analysis
119 7.2 Benefits and Limitations of ACS for Transportation Market Analysis
119 7.3 Transportation Market Analysis: Environmental Justice Case Study
126 7.4 Conclusions from the Case Study
127 7.5 Specific Uses of Census Data for Market Analyses
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131 Chapter 8 Survey Development and Analysis Using ACS Data
131 8.1 Survey Development and Analysis
132 8.2 Benefits and Limitations of ACS for Survey Development and Analysis
133 8.3 Case Study
141 Chapter 9 Travel Demand Modeling Analyses Using ACS Data
141 9.1 Travel Demand Modeling
144 9.2 Benefits and Limitations of ACS for Travel Demand Modeling
144 9.3 Travel Demand Modeling Case Studies
149 9.4 Specific Uses of Census Data for Travel Demand Modeling
151 Appendix A Housing and Population Questions
from ACS and Census Long Form
162 Appendix B ACS Base Tables
185 Appendix C ACS Data Profiles
207 Appendix D ACS Multiyear Profiles
227 Appendix E ACS Ranking Tables
234 Appendix F ACS Thematic Maps
236 Appendix G ACS Subject Tables
246 Appendix H ACS Selected Population Profiles
253 Appendix I Comparison of ACS and Decennial Census
Transportation Planning Estimates
263 Appendix J Seasonality Analyses Using ACS