TRANSPORTATION RESEARCH BOARD 2026 EXECUTIVE COMMITTEE^*

OFFICERS

Chair: Joel M. Jundt,Secretary of Transportation, South Dakota Department of Transportation, Pierre

Vice Chair: Randell Iwasaki,President and CEO, Iwasaki Consulting Services, Walnut Creek, CA

Executive Director: Victoria Sheehan,Transportation Research Board, Washington, DC

MEMBERS

James F. Albaugh,President and CEO, The Boeing Company (retired), Scottsdale, AZ

Marsha Anderson Bomar,Strategic Transportation Advisor, GHD, Duluth, GA

Douglas C. Ceva,Vice President, Customer Lead Solutions, Prologis, Inc., Jupiter, FL

Nancy Daubenberger,Commissioner of Transportation, Minnesota Department of Transportation, St. Paul

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 and Economics, Cazenovia, NY

Edward Hassinger,Director, Missouri Department of Transportation, Jefferson City

Shante Hastings,Cabinet Secretary, Delaware Department of Transportation, Dover

Carol A. Lewis,Professor, Transportation Studies, Texas Southern University, Houston

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

Leslie S. Richards,Professor of Practice, University of Pennsylvania, Philadelphia

Tracy Larkin Thomason,Director, Nevada Department of Transportation, Carson City

Marc Williams,Executive Director, Texas Department of Transportation, Austin

EX OFFICIO MEMBERS

Derek Barrs,Administrator, Federal Motor Carrier Safety Administration, Washington, DC

Steven G. Bradbury,Deputy Secretary, U.S. Department of Transportation, Washington, DC

Stephen Carmel,Administrator, U.S. Maritime Administration, Washington, DC

Tara Cavalline,Professor, University of North Carolina, Charlotte, and Chair, TRB Technical Activities Council

David Fink,Administrator, Federal Railroad Administration, Washington, DC

Firas Ibrahim,Director, Office of Research, Development, and Technology, Office of the Assistant Secretary for Research and Technology, 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, and Chair, TRB Marine Board

Sean McMaster,Administrator, Federal Highway Administration, Washington, DC

Marcus J. Molinaro,Administrator, Federal Transit Administration, Washington, DC

Jonathan Morrison,Administrator, National Highway Traffic Safety Administration, Washington, DC

Seval Oz,Senior Advisor, Office of the Assistant Secretary for Research and Technology, Washington, DC

Niloo Parvinashtiani,Engineer, Mobility Consultant Solutions, Iteris Inc., Fairfax, VA, and Chair, TRB Young Participants Council

Paul Roberti,Administrator, Pipeline and Hazardous Materials Safety Administration, 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

________________________

^* Membership as of February 2026.

NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM

NCHRP RESEARCH REPORT 1141

Delineation of Linear Roadside Hardware Systems and Roadside Obstacles

Nathan Schulz

Adam Pike

Maryam Shirinzad

Paul Carlson

Texas A&M Transportation Institute

College Station, TX

Dominique Lord

Texas A&M University

College Station, TX

Subscriber Categories

Design • Operations and Traffic Management • Safety and Human Factors

Research sponsored by the American Association of State Highway and Transportation Officials in cooperation with the Federal Highway Administration

2026

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 TRBʼs 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; TRBʼs 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&Iʼs 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 1141

Project 22-53
ISSN 2572-3766 (Print)
ISSN 2572-3774 (Online)
ISBN 978-0-309-60301-0
Library of Congress Control Number 2026934234

© 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.

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.

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. 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 of Sciences, Engineering, and Medicine; and the sponsors of the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturersʼ names or logos appear herein solely because they are considered essential to the object of the report.

Published research reports of the

NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM

are available from

National Academies Press
500 Fifth Street, NW
Washington, DC 20001

(800) 624-6242

and can be ordered through the internet by going to

nationalacademies.org/publications

Printed in the United States of America

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. Tsu-Jae Liu 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 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 RESEARCH REPORT 1141

Monique R. Evans,Director, Cooperative Research Programs

Waseem Dekelbab,Deputy Director, Cooperative Research Programs, and Manager, National Cooperative Highway Research Program

Amir N. Hanna,Senior Program Officer

Oulimata Khoule,Senior Program Assistant

Natalie Barnes,Director of Publications

Brian Haefs,Associate Director of Publications

Dominique Williams,Editor

NCHRP PROJECT 22-53 PANEL
Field of Design—Area of Vehicle Barrier Systems

Kristin Schuster,Michigan Department of Transportation, Lansing, MI (Chair)

Tracy Borchardt,AECOM, Spotsylvania, VA

Bucky D. Galloway,NCDOT (retired), Mills River, NC

Chris Lindsey,Texas Department of Transportation, Austin, TX

Filiberto Sotelo,Arora and Associates, P.C., Springfield, IL

Hung Tang,New Jersey Department of Transportation, Trenton, NJ

Qian Wang,Manhattan College, Riverdale, NY

Paul LaFleur,FHWA Liaison

AUTHOR ACKNOWLEDGMENTS

The research reported herein was performed under NCHRP Project 22-53, “Delineation of Linear Roadside Hardware Systems and Roadside Obstacles,” by the Texas A&M Transportation Institute (TTI), a member of The Texas A&M University system. The research team offers special thanks to the TTI Proving Ground Lab and the Visibility Research Lab for their assistance with the closed-course human factors study.

FOREWORD

By Amir N. Hanna
Staff Officer
Transportation Research Board

NCHRP Research Report 1141: Delineation of Linear Roadside Hardware Systems and Roadside Obstacles provides information on the practices for delineating linear roadside hardware systems and roadside obstacles, including their descriptions, effectiveness, and appropriate applications. This information was developed from (1) a review and evaluation of current practices relevant to the delineation of linear roadside hardware systems and roadside obstacles, (2) an analysis of crash data and the effectiveness of delineation practices in reducing crash severity or crash frequency, and (3) a human factors study evaluating the effectiveness of several roadside hardware and roadside obstacle delineation practices. The information contained in this report will help highway agencies and other organizations concerned with safety aspects on highways make informed decisions regarding the delineation of roadside hardware and obstacles to reduce crashes and improve safety.

The advancement and implementation of roadside safety hardware on roadways have led to a reduction in crash severity when errant vehicles exit roadways. The crashworthiness of such roadside safety hardware is evaluated through full-scale crash testing conducted in a controlled environment that lacks the consideration of human factors and driversʼ reactions to delineation practices present on the roadside safety hardware. Some state departments of transportation have reported that enhanced continuous delineation of roadside hardware has led to a reduction in crashes. Similarly, applying specific practices for delineating roadside obstacles has led to a reduction in crashes. However, no widely accepted guidelines exist on applying delineation practices and their effectiveness in reducing crashes. Research was needed to identify and evaluate current practices for delineating linear roadside hardware systems and roadside obstacles and to develop guidelines for facilitating the application of practices that will reduce crashes and enhance safety.

Under NCHRP Project 22-53, “Delineation of Linear Roadside Hardware Systems and Roadside Obstacles,” Texas A&M Transportation Institute was tasked with (1) developing guidelines for delineating linear roadside hardware systems and roadside obstacles to enhance safety and (2) proposing draft language to update relevant documents. To accomplish these objectives, a review and evaluation of current practices relevant to the delineation of linear roadside hardware systems and roadside obstacles to enhance safety were conducted. A crash data analysis was also performed to investigate the effectiveness of delineation practices in reducing crash severity or frequency. In addition, a human factors study was conducted to evaluate the effectiveness of several roadside hardware and obstacle delineation practices, either individually or in combination.

Lastly, this information and research findings were used to develop guidelines for delineating roadside hardware and obstacles and their effectiveness and to propose draft language

for minor updates to the Manual on Uniform Traffic Control Devices for consideration by the FHWA, as well as the Roadside Design Guide and the Policy on Geometric Design of Highways and Streets for consideration by AASHTO. The proposed draft language updates call for citing NCHRP Research Report 1141 and its findings in relevant documents. It is not published herein but provided to the responsible organizations for consideration and implementation as appropriate.

CONTENTS

Summary

PART I Research Overview

Chapter 1 Introduction

Chapter 2 Background and Current Practice

Chapter 3 Crash Data Analysis and Findings

Chapter 4 Human Factors Study and Findings

Chapter 5 Conclusions and Suggested Research

PART II Guidelines

Chapter 6 Introduction

Chapter 7 Guardrail Delineation

Chapter 8 Concrete Barrier Delineation

Chapter 9 Cable Barrier Delineation

Chapter 10 End Treatment and Crash Attenuators Delineation

Chapter 11 Roadside Obstacle Delineation

References

Appendix A State Survey Questionnaire

Appendix B State DOT Delineation Practices

Appendix C Description of Delineation Practices Evaluated in Human Factors Study