Tracking Safety Leading Indicators to Improve DOT Employee Safety Performance (2025)
Chapter: Front Matter
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| NCHRP Synthesis 637 A SYNTHESIS OF HIGHWAY PRACTICE |
National Cooperative Highway Research Program |
Tracking Safety Leading Indicators
to Improve DOT Employee
Safety Performance
TRANSPORTATION RESEARCH BOARD 2024 EXECUTIVE COMMITTEE*
OFFICERS
CHAIR: Carol A. Lewis, Professor, Transportation Studies, Texas Southern University, Houston
VICE CHAIR: Leslie S. Richards, General Manager, Southeastern Pennsylvania Transportation Authority (SEPTA), Philadelphia
EXECUTIVE DIRECTOR: Victoria Sheehan, Transportation Research Board, Washington, DC
MEMBERS
Michael F. Ableson, CEO, Arrival Automotive–North America, Detroit, MI
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
Chris T. Hendrickson, Hamerschlag University Professor of Engineering Emeritus, Carnegie Mellon University, Pittsburgh, PA
Randell Iwasaki, President and CEO, Iwasaki Consulting Services, Walnut Creek, CA
Ashby Johnson, Executive Director, Capital Area Metropolitan Planning Organization (CAMPO), Austin, TX
Joel M. Jundt, Secretary of Transportation, South Dakota Department of Transportation, Pierre
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
Michael R. McClellan, Vice President, Strategic Planning, Norfolk Southern Corporation, Atlanta, 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
Amit Bose, Administrator, Federal Railroad Administration, Washington, DC
Tristan Brown, Deputy Administrator, Pipeline and Hazardous Materials Safety Administration, U.S. Department of Transportation, Washington, DC
Steven Cliff, Executive Officer, California Air Resources Board, Sacramento
Rand Ghayad, Senior Vice President, Association of American Railroads, Washington, DC
LeRoy Gishi, Chief, Division of Transportation, Bureau of Indian Affairs, U.S. Department of the Interior, Germantown, MD
Robert C. Hampshire, Deputy Assistant Secretary for Research and Technology, U.S. Department of Transportation, Washington, DC
Jason Kelly, Deputy Commanding General for Civil Works and Emergency Operations, U.S. Army Corps of Engineers, Washington, DC
Zahra “Niloo” Parvinashtiani, Engineer, Mobility Consultant Solutions, Iteris Inc., Fairfax, VA, and Chair, TRB Young Members Coordinating Council
Ann Phillips (Rear Admiral, U.S. Navy, retired), Maritime Administrator, Maritime Administration, U.S. Department of Transportation, Washington, DC
Sophie Shulman, Deputy Administrator, National Highway Traffic Safety 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
Polly Trottenberg, Deputy Secretary of Transportation, U.S. Department of Transportation, Washington, DC
Jim Tymon, Executive Director, American Association of State Highway and Transportation Officials, Washington, DC
Veronica Vanterpool, Acting Administrator, Federal Transit Administration, Washington, DC
Michael Whitaker, Administrator, Federal Aviation Administration, U.S. Department of Transportation, Washington, DC
Kristin White, Acting Administrator, Federal Highway Administration, U.S. Department of Transportation, Washington, DC
Vinn White, Deputy Administrator, Federal Motor Carrier Safety Administration, Washington, DC
___________________
* Membership as of November 2024.
NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM
NCHRP SYNTHESIS 637
Tracking Safety Leading Indicators
to Improve DOT Employee
Safety Performance
A Synthesis of Highway Practice
Gabriel B. Dadi
Roy E. Sturgill, Jr.
BLUE HARDHAT CONSULTING LLC
Lexington, KY
Subscriber Categories
Construction • Education and Training • Safety and Human Factors
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 departments of transportation (DOTs) 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, under Agreement No. 693JJ31950003.
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 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 surveillance of research contracts are the responsibilities of the National Academies and TRB.
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 637
Project 20-05, Topic 55-15
ISSN 0547-5570
ISBN 978-0-309-73194-2
Library of Congress Control Number 2024950221
Digital Object Identifier: 10.17226/28599
© 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
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, 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.
Cover image description: Highway construction employee with the Kentucky Transportation Cabinet in high visibility vest and other safety personal protective equipment.
Credit: Photograph taken and released by Paul Ross, Kentucky Transportation Center Marketing, Media, and Technical Review Group.
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.
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 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 of Sciences, Engineering, and Medicine; and the sponsors of the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturers’ names or logos appear herein solely because they are considered essential to the object of the report.
Published reports of the
NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM
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The National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, nongovernmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Marcia McNutt is president.
The National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. John L. Anderson is president.
The National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president.
The three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. The National Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine.
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.
COOPERATIVE RESEARCH PROGRAMS
CRP STAFF FOR NCHRP SYNTHESIS 637
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
Mazen Alsharif, Senior Program Assistant
Natalie Barnes, Director of Publications
Heather DiAngelis, Associate Director of Publications
NCHRP PROJECT 20-05 PANEL
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
Jim McDonnell, AASHTO Liaison
TOPIC 55-15 PANEL
Tracy Fletcher, Alabama Department of Transportation, Montgomery, AL
Mario Gomez, Nevada Department of Transportation, Las Vegas, NV
Susan B. Herbel, SBH Consult, Fort Myers, FL
Larry David Schwartz, California Department of Transportation, McClellan, CA
Troy Whitworth, Kansas Department of Transportation, Topeka, KS
Zhenyu Zhang, Texas A&M University, College Station, TX
Connie Kelly Tang, FHWA Liaison
Ilona Ottilia Kastenhofer, TRB Liaison
ABOUT THE NCHRP SYNTHESIS PROGRAM
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.
FOREWORD
By Trey Joseph Wadsworth
Staff Officer
Transportation Research Board
The objective of this synthesis is to document practices used by state departments of transportation (DOTs) regarding the use of safety leading indicators to track and prevent occupational injuries and other incidents. For the safety and health of state DOT employees, the primary, historic metric used has been the Occupational Safety and Health Administration recordable incident rate. This incident rate measures how often a state DOT employee sustains an injury that demands more than basic first aid. This metric is important for understanding injury frequency but does not assist with programmatic management of the safety, health, and overall well-being of state DOT personnel. Public and private sector organizations with high-hazard tasks have turned to safety leading indicators as metrics to manage occupational safety and health. These safety leading indicators provide relevant data before an incident occurs and thus can lead to predictive insights that allow state DOTs to take action to avoid incidents altogether.
This synthesis gathered information through a literature review, a survey of DOTs, and follow-up interviews with selected DOTs. Five case examples provide greater insight into current gender equity practices, barriers to implementation, data collection and accountability processes, and assessment findings. Appendix D is a supplemental document that provides DOT safety leading indicator policies and may be found on the National Academies Press website (nap.nationalacademies.org) by searching for NCHRP Synthesis 637: Tracking Safety Leading Indicators to Improve DOT Employee Safety Performance and then looking under RESOURCES.
Gabriel B. Dadi and Roy Sturgill, Jr., of Blue Hardhat Consulting LLC, led a team that collected and synthesized the information and wrote the report. The members of the topic panel are acknowledged on page iv. 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. As progress in research and practice continues, new knowledge will be added to that now at hand.
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CONTENTS
2.1 Traditional Safety Performance Indicators
2.2 Definition of Leading Indicators
2.3 Development of Leading Safety Indicators in the Construction Industry
2.4 Leading Indicators Safety Categorization
2.5 Effectiveness of Leading Indicators
3.2 Use of Safety Leading Indicators
3.3 Implementation and Results
3.4 Written Policies and Procedures
3.5 State DOTs not Currently Documenting Safety Leading Indicators
4.1 Colorado Department of Transportation
4.2 Delaware Department of Transportation
4.3 Illinois Department of Transportation
4.4 Virginia Department of Transportation
4.5 Washington State Department of Transportation
Appendix A Survey Questionnaire
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