| NCHRP Synthesis 651 A SYNTHESIS OF HIGHWAY PRACTICE |
National Cooperative Highway Research Program |
Practices to Enhance Resiliency of Existing Roadway and Embankment Culverts

CHAIR: Leslie S. Richards, Professor of Practice, University of Pennsylvania, Philadelphia
VICE CHAIR: Joel M. Jundt, Secretary of Transportation, South Dakota Department of Transportation, Pierre
EXECUTIVE DIRECTOR: Victoria Sheehan, Transportation Research Board, Washington, DC
James F. Albaugh, President and CEO, The Boeing Company (retired), Scottsdale, AZ
Carlos M. Braceras, Executive Director, Utah Department of Transportation, Salt Lake City
Douglas C. Ceva, Vice President, Customer Lead Solutions, Prologis, Inc., Jupiter, FL
Nancy Daubenberger, Commissioner of Transportation, Minnesota Department of Transportation, St. Paul
Marie Therese Dominguez, Commissioner, New York State Department of Transportation, Albany
Garrett Eucalitto, Commissioner, Connecticut Department of Transportation, Newington
Andrew Fremier, Executive Director, Metropolitan Transportation Commission, San Francisco, CA
Martha Grabowski, Professor Emerita, Information Systems, Le Moyne College, Madden College of Business & Economics, Cazenovia, NY
Randell Iwasaki, President and CEO, Iwasaki Consulting Services, Walnut Creek, CA
Carol A. Lewis, Professor, Transportation Studies, Texas Southern University, Houston
Hani S. Mahmassani, W.A. Patterson Distinguished Chair in Transportation; Director, Transportation Center, Northwestern University, Evanston, IL
Scott C. Marler, Director, Iowa Department of Transportation, Ames
Ricardo Martinez, Adjunct Professor of Emergency Medicine, Emory University School of Medicine, Decatur, GA
Russell McMurry, Commissioner, Georgia Department of Transportation, Atlanta
Craig E. Philip, Research Professor and Director, VECTOR, Department of Civil and Environmental Engineering, Vanderbilt University, Nashville, TN
Steward T.A. Pickett, Distinguished Senior Scientist, Cary Institute of Ecosystem Studies, Millbrook, NY
Susan A. Shaheen, Professor and Co-Director, Transportation Sustainability Research Center, University of California, Berkeley
Marc Williams, Executive Director, Texas Department of Transportation, Austin
Michael R. Berube, Deputy Assistant Secretary for Sustainable Transportation, U.S. Department of Energy, Washington, DC
Steven G. Bradbury, Deputy Secretary, U.S. Department of Transportation, Washington, DC
Steven Cliff, Executive Officer, California Air Resources Board, Sacramento
LeRoy Gishi, Chief, Division of Transportation, Bureau of Indian Affairs, U.S. Department of the Interior, Germantown, MD
Firas Ibrahim, Director, Office of Research, Development, and Technology, Office of the Assistant Secretary for Research and Technology (OST-R), Washington, DC
Jason Kelly, Deputy Commanding General for Civil Works and Emergency Operations, U.S. Army Corps of Engineers, Washington, DC
Sandra Knight, President, WaterWonks, LLC, Washington, DC
Ben Kochman, Acting Administrator, Pipeline and Hazardous Materials Safety Administration, Washington, DC
Zahra “Niloo” Parvinashtiani, Engineer, Mobility Consultant Solutions, Iteris Inc., Fairfax, VA, and Chair, TRB Young Members Coordinating Council
Chris Rocheleau, Acting Administrator, Federal Aviation Administration, Washington, DC
Gloria Shepherd, Acting Deputy Administrator, Federal Highway Administration, Washington, DC
Karl Simon, Director, Transportation and Climate Division, U.S. Environmental Protection Agency, Washington, DC
Paul P. Skoutelas, President and CEO, American Public Transportation Association, Washington, DC
Jim Tymon, Executive Director, American Association of State Highway and Transportation Officials, Washington, DC
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* Membership as of May 2025.
NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM
NCHRP SYNTHESIS 651
A Synthesis of Highway Practice
Michael Pluimer
Sara Stone
CROSSROADS ENGINEERING SERVICES, LLC
Duluth, MN
Subscriber Categories
Bridges and Other Structures • Construction • Maintenance and Preservation
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, 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.
The Transportation Research Board (TRB) of the National Academies of Sciences, Engineering, and Medicine was requested by AASHTO to administer the research program because of TRB’s recognized objectivity and understanding of modern research practices. TRB is uniquely suited for this purpose for many reasons: TRB maintains an extensive committee structure from which authorities on any highway transportation subject may be drawn; TRB possesses avenues of communications and cooperation with federal, state, and local governmental agencies, universities, and industry; TRB’s relationship to the National Academies is an insurance of objectivity; and TRB maintains a full-time staff of specialists in highway transportation matters to bring the findings of research directly to those in a position to use them.
The program is developed on the basis of research needs identified by chief administrators and other staff of the highway and transportation departments, by committees of AASHTO, and by the FHWA. Topics of the highest merit are selected by the AASHTO Special Committee on Research and Innovation (R&I), and each year R&I’s recommendations are proposed to the AASHTO Board of Directors, the FHWA, and the National Academies. Research projects to address these topics are defined by NCHRP, and qualified research agencies are selected from submitted proposals. Administration and oversight of research contracts are the responsibilities of NCHRP.
The needs for highway research are many, and NCHRP can make significant contributions to solving 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.
NCHRP SYNTHESIS 651
Project 20-05, Topic 55-17
ISSN 0547-5570
ISBN 978-0-309-99294-7
Library of Congress Control Number 2025940082
Digital Object Identifier: 10.17226/29134
© 2025 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.
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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.
NOTICE
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 National Academies of Sciences, Engineering, and Medicine.
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.
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Learn more about the National Academies of Sciences, Engineering, and Medicine at www.nationalacademies.org.
The Transportation Research Board is one of seven major program divisions 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 about 8,500 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 the 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.
Monique R. Evans, Director, Cooperative Research Programs
Waseem Dekelbab, Deputy Director, Cooperative Research Programs, and Manager, National Cooperative Highway Research Program
Sandra Larson, Senior Program Officer
Anthony P. Avery, Senior Program Assistant
Natalie Barnes, Director of Publications
Heather DiAngelis, Associate Director of Publications
Doug English, Senior Editor
Joyce N. Taylor, Maine Department of Transportation, Augusta, ME (Chair)
Anita K. Bush, CDM Smith, Carson City, NV
Joseph D. Crabtree, Kentucky Transportation Center, Lexington, KY
Mostafa Jamshidi, Nebraska Department of Transportation, Lincoln, NE
Jessie X. Jones, Arkansas Department of Transportation, Little Rock, AR
Raymond J. Khoury, Virginia Department of Transportation, Richmond, VA
Brenda Moore, North Carolina Department of Transportation (retired), Cary, NC
Jesus Alberto Sandoval-Gil, Arizona Department of Transportation, Phoenix, AZ
Cynthia J. Smith, Mississippi Department of Transportation, Jackson, MS
Jean M. Wallace, Minnesota Department of Transportation, St. Paul, MN
Mary Huie, FHWA Liaison
Luke Assink, Washington State Department of Transportation, Olympia, WA
Shunyi Christopher Chen, North Carolina Department of Transportation, Apex, NC
Jeffrey A. DeGraff, Vermont Agency of Transportation, Barre, VT
Jimmy Duong, California Department of Transportation, Elk Grove, CA
Lindsey Merrifield, Maine Department of Transportation, Augusta, ME
Michelle O’Neill, Michigan Department of Transportation, Kalamazoo, MI
Mary Lou Ralls Newman, Ralls Newman, LLC, Georgetown, TX
David Richard Claman, FHWA Liaison
Highway administrators, engineers, and researchers often face problems for which information already exists, either in documented form or as undocumented experience and practice. This information may be fragmented, scattered, and unevaluated. As a consequence, full knowledge of what has been learned about a problem may not be brought to bear on its solution. Costly research findings may go unused, valuable experience may be overlooked, and due consideration may not be given to recommended practices for solving or alleviating the problem.
There is information on nearly every subject of concern to highway administrators and engineers. Much of it derives from research or from the work of practitioners faced with problems in their day-to-day work. To provide a systematic means for assembling and evaluating such useful information and to make it available to the entire highway community, the American Association of State Highway and Transportation Officials—through the mechanism of the National Cooperative Highway Research Program—authorized the Transportation Research Board to undertake a continuing study. This study, NCHRP Project 20-05, “Synthesis of Information Related to Highway Practices,” searches out and synthesizes useful knowledge from all available sources and prepares concise, documented reports on specific topics. Reports from this endeavor constitute an NCHRP report series, Synthesis of Highway Practice.
This synthesis series reports on current knowledge and practice, in a compact format, without the detailed directions usually found in handbooks or design manuals. Each report in the series provides a compendium of the best knowledge available on those measures found to be the most successful in resolving specific problems.
By Sandra Larson
Staff Officer
Transportation Research Board
Culverts are buried drainage structures underneath roadways or embankments that are open at both ends and used to convey and transport water. Culverts were frequently identified as vulnerable components to extreme weather events and climate change during a 2013–2015 pilot study (FHWA-HEP-16-079), and many culverts under the jurisdiction of state departments of transportation (DOTs) were designed and installed well before the effects of climate change were understood or realized. Existing culverts must be able to handle the increasing frequency and severity of extreme weather events [National Oceanic and Atmospheric Administration (NOAA) 2023; Pluimer 2023], which can accelerate failure mechanisms and shorten culvert expected design lifetimes. Accelerated deterioration of culverts can lead to a suite of unplanned repairs, rehabilitation projects, or full replacements, all of which are financially burdensome and present issues of staffing or sourcing of work to state DOTs. The needs of state DOTs to improve resilience are common, but practices may be diverse due to variability in climate, weather events, seismic susceptibility, slope and embankment stability, watershed characteristics, and challenges due to urban development and land usage.
The objective of this synthesis is to document management and maintenance practices used by state DOTs to enhance resiliency of existing roadway and embankment culverts.
Information for this study was gathered through a literature review, a survey of state DOTs, and follow-up interviews with selected DOTs. Case examples of five state DOTs provide additional information related to their maintenance practices for wide cracks and joints in flexible and composite pavements.
Michael Pluimer, Ph.D. and Sara Stone, M.S., Crossroads Engineering Services, LLC, collected and synthesized the information and wrote the report. The members of the topic panel are acknowledged. This synthesis is an immediately useful document that records practices that were acceptable within the limitations of the knowledge available at the time of its preparation.
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1.3 Synthesis Scope and Approach
2.1 Federal Legislation and Regulation
2.2 Trade Association Information on Resilience
2.4 Select State DOT Approaches to Resilience
Chapter 3 State of the Practice (Survey Results)
3.1 Culvert Types and Materials Employed by DOTs
3.2 Life-Cycle Cost Analysis and Risk Assessment Methodologies
3.3 Current Maintenance and Management Practices
3.4 Failure Mechanisms, Durability, and Practices to Enhance Resiliency
3.5 Types of Extreme Weather Events of Concern for Culvert Resilience
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