Mechanistic-Empirical Pavement Design Model: Enhancements of Climatic Inputs (2025)
Chapter: Front Matter
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| NCHRP Research Report 1151 |
National Cooperative Highway Research Program |
Mechanistic-Empirical Pavement
Design Model
ENHANCEMENTS OF CLIMATIC INPUTS
TRANSPORTATION RESEARCH BOARD 2025 EXECUTIVE COMMITTEE*
OFFICERS
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
MEMBERS
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
EX OFFICIO MEMBERS
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 RESEARCH REPORT 1151
Mechanistic–Empirical Pavement Design Model
ENHANCEMENTS OF CLIMATIC INPUTS
Wouter Brink
Zafrul Khan
Byungkyu Moon
APPLIED RESEARCH ASSOCIATES, INC.
Champaign, IL
Subscriber Categories
Data and Information Technology • Environment • Pavements
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 RESEARCH REPORT 1151
Project 20-50(21)A
ISSN 2572-3766 (Print)
ISSN 2572-3774 (Online)
ISBN 978-0-309-99256-5
Library of Congress Control Number 2025938331
Digital Object Identifier: 10.17226/29125
© 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.
COPYRIGHT INFORMATION
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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, APTA, FAA, FHWA, FTA, GHSA, or NHTSA 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 research 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. The opinions, findings, and conclusions or recommendations expressed or implied in this publication 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.
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COOPERATIVE RESEARCH PROGRAMS
CRP STAFF FOR NCHRP RESEARCH REPORT 1151
Monique R. Evans, Director, Cooperative Research Programs
Waseem Dekelbab, Deputy Director, Cooperative Research Programs, and Manager, National Cooperative Highway Research Program
Christopher T. McKenney, Senior Program Officer
Sheila A. Moore, Program Associate
Natalie Barnes, Director of Publications
Heather DiAngelis, Associate Director of Publications
Dominique Williams, Editor
NCHRP PROJECT 20-50(21)A PANEL
Field of Special Projects
Giri Venkiteela, New Jersey Department of Transportation, Trenton, NJ (Chair)
Imad A Basheer, California Department of Transportation, Sacramento, CA
Xingwei Chen, Louisiana Department of Transportation and Development, Baton Rouge, LA
Bruce Dietrich, Tallahassee, FL
Bob Frank, RAP Technologies LLC, South Pasadena, FL
Kang-Won Wayne Lee, University of Rhode Island, Kingston, RI
Tommy E. Nantung, Indiana Department of Transportation, West Lafayette, IN
Jane Jiang, FHWA Liaison
FOREWORD
By Christopher T. McKenney
Staff Officer
Transportation Research Board
NCHRP Research Report 1151: Mechanistic–Empirical Pavement Design Model: Enhancements of Climatic Inputs presents a state-of-the-art update to pavement design procedures to better enhance and simplify the climatic input parameters of predicted pavement temperatures. The development of this update was based on climate-related models and comprehensive laboratory investigations, resulting in recommendations for enhancing climatic inputs in pavement design. This update will be of immediate interest to design and pavement engineers.
NASA’s Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2) has used data from its Earth Observing System satellites to enhance precipitation and water vapor climatology since 1979. FHWA and AASHTO have adopted MERRA-2, integrating its variables into civil engineering applications, particularly pavement design. FHWA’s Long-Term Pavement Performance (LTPP) Climate Tool provides access to the MERRA-2 database and generates site-specific climate data in compatible formats for the AASHTO Pavement Mechanistic–Empirical (Pavement ME) Design.
MERRA-2 data provide opportunities for enhancements to the climatic parameters and module calculations for pavement design using Pavement ME. They also provide improved climatology; higher frequency outputs, including hourly data updates; and additional locations beyond the United States. Additionally, studies have shown the impediments to aligning parameters from the Enhanced Integrated Climatic Model with field observations and pavement performance as well as the variations in climatic attribute measurements reported by operating weather stations. Research was needed to develop climate-related models based on identified parameter enhancements that could be implemented into state agencies’ asset and pavement management systems.
Under NCHRP Project 20-50(21)A, “Enhancements of Climatic Inputs and Related Models for Pavement ME Using LTPP Climate Tool (MERRA-2),” Applied Research Associates, Inc., was asked to evaluate the impact of using NASA’s MERRA-2 to improve the climatic inputs and related models for Pavement ME that can be implemented by transportation agencies. The research included a synopsis for an implementation plan developed by the research team in collaboration with AASHTO/AASHTOWare based on the research findings.
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CONTENTS
Chapter 1 Background and Research Approach
1.3 Organization of the Report
Chapter 3 Interpretations and Applications
3.1 Improving and Simplifying the Climate Input Parameters for Pavement ME
3.3 Validating New or Enhanced Models
3.4 Identifying Enhancements to Improve EICM Functionality and Maintainability
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