Developing a Guide for Incorporating Uncertainty into Long-Range Transportation Planning (2026)
Chapter: Front Matter
Developing a Guide for
Incorporating Uncertainty
into Long-Range
Transportation Planning
Naomi Stein
Allison Van Twisk
Hajra Shahab
Kyle Schroeckenthaler
Adam Schmidt
Daniel Mascoop
EBP US, Inc
Boston, MA
Peter Hylton
Bryce Miller
Alice Beattie
High Street Consulting Group
Pittsburgh, PA
Adiele Nwankwo
Cincar Consulting (C2G)
Atlanta, GA
Colleen Turner
Michael Baker International
Baltimore, MD
Larry Redd
Redd Engineering
Fort Collins, CO
Conduct of Research Report for NCHRP Project 08-154
Submitted December 2025
NCHRP Web-Only Document 440
Developing a Guide for Incorporating Uncertainty into Long-Range Transportation Planning
© 2026 by the National Academy of Sciences. National Academies of Sciences, Engineering, and Medicine and the graphical logo are trademarks of the National Academy of Sciences. All rights reserved.
NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM
Systematic, well-designed, and implementable research is the most effective way to solve many problems facing state department of transportation (DOT) administrators and engineers. Often, highway problems are of local or regional interest and can best be studied by state DOTs individually or in cooperation with their state universities and others. However, the accelerating growth of highway transportation results in increasingly complex problems of wide interest to highway authorities. These problems are best studied through a coordinated program of cooperative research.
Recognizing this need, the leadership of the American Association of State Highway and Transportation Officials (AASHTO) in 1962 initiated an objective national highway research program using modern scientific techniques—the National Cooperative Highway Research Program (NCHRP). NCHRP is supported on a continuing basis by funds from participating member states of AASHTO and receives the full cooperation and support of the Federal Highway Administration (FHWA), United States Department of Transportation.
COPYRIGHT INFORMATION
Authors herein are responsible for the originality and accuracy 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.
The National Academy of Sciences (NAS) grants permission to reproduce written material in this publication for classroom and non-commercial purposes subject to the rights of any third parties and appropriate attribution. Permission is given with the understanding that none of the material will be used to imply NAS, TRB, AASHTO, APTA, FAA, FHWA, FTA, GHSA, or NHTSA endorsement of a particular product, method, or practice. For other uses of the written material, users must request permission from the National Academies Press.
DISCLAIMER
This material is based upon work supported by the FHWA under Agreement No. 693JJ32350025. Any opinions, findings, and conclusions or recommendations expressed or implied in this document are those of the researchers who performed the research and are not necessarily those of the Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; the FHWA; or the program sponsors.
The Transportation Research Board does not develop, issue, or publish standards or specifications. The Transportation Research Board manages applied research projects which provide the scientific foundation that may be used by Transportation Research Board sponsors, industry associations, or other organizations as the basis for revised practices, procedures, or specifications.
The Transportation Research Board, the National Academies, 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 information contained in this document was taken directly from the submission of the author(s). This material has not been edited by TRB.
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The Transportation Research Board is one of four centers of the National Academies of Sciences, Engineering, and Medicine. The mission of the Transportation Research Board is to mobilize expertise, experience, and knowledge to anticipate and solve complex transportation-related challenges. The Board’s varied activities annually engage more than 5,500 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 departments of transportation, federal agencies including component administrations of the U.S. Department of Transportation, and other organizations and individuals interested in the development of transportation.
Learn more about the Transportation Research Board at www.TRB.org.
COOPERATIVE RESEARCH PROGRAMS
CRP STAFF FOR NCHRP WEB-ONLY DOCUMENT 440
Monique R. Evans, Director, Cooperative Research Programs
Waseem Dekelbab, Deputy Director, Cooperative Research Programs, and Manager, National Cooperative Highway Research Program
Trey Joseph Wadsworth, Senior Program Officer
Tijhuana Stapleton, Senior Program Assistant
Natalie Barnes, Director of Publications
Brian Haefs, Associate Director of Publications
Alison Shapiro, Editor
Jennifer J. Weeks, Publishing Projects Manager
NCHRP PROJECT 08-154 PANEL
Field of Transportation Planning – Area of Planning Methods & Processes
Jennifer Z. Carver, Florida Department of Transportation, Tallahassee, FL (Chair)
Elizabeth G. D. Alden, Tampa, FL
Baloka Belezamo, Arizona Department of Transportation, Phoenix, AZ
Ryan Granger, HNTB, Austin, TX
Benjamin Neal Williams Muller, Massachusetts Department of Transportation, Boston, MA
Bradley M. Sharlow, Michigan Department of Transportation, Lansing, MI
John Spruijt Sr., XTNT, Rijswijk, the Netherlands
Flavia Tsang, Metropolitan Transportation Commission, San Francisco, CA
Carole Turley Voulgaris, Harvard University, Cambridge, MA
Chandra Inglis-Smith, FHWA Liaison
John Dean, AASHTO Liaison
Contents
Summary of Phase I: Foundational Research, Outreach, and Case Studies
Phase II: Summary of NCHRP Research Report 1168 Guide, Toolkit, Testing, and Peer Exchange
Task 5. Development of Guidance and Toolkit
Testing of Guidance and Toolkit
Appendix A: Foundational Research: Uncertainty Drivers, Data, and Methods
Appendix B: Outreach Summary: Questionnaire and Focus Groups
Appendix D: Agency Testing Workshops
Appendix E: Testing Peer Exchange Summary
NCHRP Web-Only Document 440 contains the conduct of research report for NCHRP Project 08-154 and accompanies NCHRP Research Report 1168: Incorporating Uncertainty into Long-Range Transportation Planning: A Guide. Readers can read or purchase NCHRP Research Report 1168 on the National Academies Press website (nationalacademies.org/publications).
