Behavioral Traffic Safety Messaging on Variable Message Signs (2022)

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2022 B E H A V I O R A L T R A F F I C S A F E T Y C O O P E R A T I V E R E S E A R C H P R O G R A M BTSCRP RESEARCH REPORT 3 Research sponsored by the Governors Highway Safety Association and National Highway Trafc Safety Administration Subscriber Categories Highways • Operations and Trafc Management • Safety and Human Factors Behavioral Trafc Safety Messaging on Variable Message Signs Gerald L. Ullman Laura L. Higgins Susan T. Chrysler Tina S. Geiselbrecht Chris L. Simek Gretchen Stoeltje Texas A&M Transportation Institute College Station, TX David Wolfe Gabrielle Benson Drive Engineering Corp. Blue Bell, PA

BEHAVIORAL TRAFFIC SAFETY COOPERATIVE RESEARCH PROGRAM Since the widespread introduction of motor vehicles more than a century ago, crashes involving their operation remain a significant public health concern. While there have been enormous improvements in highway design and construction, as well as motor vehicle safety, which have been instrumental in lowering the rate of crashes per mil- lion miles in the United States, more than 35,000 people die every year in motor vehicle crashes. In far too many cases, the root causes of the crashes are the unsafe behaviors of motor vehicle operators, cyclists, and pedestrians. Understanding human behaviors and developing effective countermeasures to unsafe ones is difficult and remains a major weakness in our traffic safety efforts. The Behavioral Traffic Safety Cooperative Research Program (BTSCRP) develops practical solutions to save lives, prevent injuries, and reduce costs of road traffic crashes associated with unsafe behav- iors. BTSCRP is a forum for coordinated and collaborative research efforts. It is managed by the Transportation Research Board (TRB) under the direction and oversight of the Governors Highway Safety Association (GHSA) with funding provided by the National Highway Traffic Safety Administration (NHTSA). Funding for the program was originally established in Moving Ahead for Progress in the 21st Century (MAP-21), Subsection 402(c), which created the National Cooperative Research and Evaluation Program (NCREP). Fixing America’s Surface Transportation (FAST) Act continued the program. In 2017, GHSA entered into an agreement with TRB to manage the research activities, with the program name changed to Behavioral Traf- fic Safety Cooperative Research Program. The GHSA Executive Board serves as the governing board for the BTSCRP. The Board consists of officers, representatives of the 10 NHTSA regions, and committee and task force chairs. The Research Committee Chair appoints committee members who recommend projects for funding and provide oversight for the activities of BTSCRP. Its ultimate goal is to oversee a quality research program that is committed to addressing research issues fac- ing State Highway Safety Offices. The Executive Board meets annu- ally to approve research projects. Each selected project is assigned to a panel, appointed by TRB, which provides technical guidance and counsel throughout the life of the project. The majority of panel mem- bers represent the intended users of the research projects and have an important role in helping to implement the results. BTSCRP produces a series of research reports and other products such as guidebooks for practitioners. Primary emphasis is placed on disseminating BTSCRP results to the intended users of the research: State Highway Safety Offices and their constituents. BTSCRP RESEARCH REPORT 3 Project BTS-02 ISSN 2766-5976 (Print) ISSN 2766-5984 (Online) ISBN 978-0-309-68713-3 Library of Congress Control Number 2022939742 © 2022 by the National Academy of Sciences. National Academies of Sciences, Engineering, and Medicine and the graphical logo are trade- marks 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, FAA, FHWA, FTA, GHSA, NHTSA, or TDC 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. 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 Transporta- tion Research Board; the National Academies of Sciences, Engineering, and Medicine; or the program sponsors. The Transportation Research Board does not develop, issue, or publish standards or speci- fications. 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 Behavioral Traffic Safety Cooperative 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 research reports of the BEHAVIORAL TRAFFIC SAFETY COOPERATIVE RESEARCH PROGRAM are available from Transportation Research Board Business Office 500 Fifth Street, NW Washington, DC 20001 and can be ordered through the Internet by going to https://www.mytrb.org/MyTRB/Store/default.aspx Printed in the United States of America

e National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, non- governmental 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. e 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. e 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. e 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. e 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. e Transportation Research Board is one of seven major programs of the National Academies of Sciences, Engineering, and Medicine. e mission of the Transportation Research Board is to provide leadership in transportation improvements and innovation through trusted, timely, impartial, and evidence-based information exchange, research, and advice regarding all modes of transportation. e Board’s varied activities annually engage about 8,000 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. e program is supported by state transportation departments, 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.

AUTHOR ACKNOWLEDGMENTS This Guide was developed under Behavioral Traffic Safety Cooperative Research Program (BTSCRP) Project BTS-02 by the Texas A&M Transportation Institute (TTI) of the Texas A&M University System, under the fiscal administration of the Texas A&M Sponsored Research Services. Drive Engineering Cor- poration served as a subcontractor on this research. Dr. Gerald Ullman was the principal investigator. The other authors of this report were Laura Higgins, Susan Chrysler, Tina Geiselbrecht, Chris Simek, Gretchen Stoeltje, David Wolfe, and Gabrielle Benson. The work was performed under the general supervision of Dr. Ullman. The researchers wish to express their gratitude to the members of the project panel for their guidance during the performance of this research. In addition to the project panel members, the authors gratefully acknowledge the assistance of numerous state and municipal departments of transportation personnel who participated in a survey of state and local practices and who provided behavioral traffic safety (BTS) messages they have used on their variable message signs. Those BTS messages that conform to the prin- ciples described in this Guide have been incorporated into Appendix A as examples of good practices. C O O P E R A T I V E R E S E A R C H P R O G R A M S CRP STAFF FOR BTSCRP RESEARCH REPORT 3 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs William C. Rogers, Senior Program Officer (retired) Richard A. Retting, Senior Program Officer Dajaih Bias-Johnson, Senior Program Assistant Natalie Barnes, Director of Publications Heather DiAngelis, Associate Director of Publications BTSCRP PROJECT BTS-02 PANEL Angela J. Kargel, Oregon Department of Transportation, Salem, OR (Chair) Chris Bortz, Kansas Department of Transportation, Topeka, KS Leanna Depue, Governors Highway Safety Association (GHSA), Belton, TX Trilce Marie Encarnacion, University of Missouri–St. Louis, St. Louis, MO Joseph M. Jeffrey, Road-Tech Safety Services, Inc., Shingle Springs, CA Janet L. Kenny, Montana Department of Transportation, Helena, MT Elisabeta Mitran, Louisiana Department of Transportation and Development, Baton Rouge, LA Hellon G. Ogallo, Maryland State Highway Administration, Hanover, MD Asfand Yar Siddiqui, California Department of Transportation (CALTRANS), Sacramento, CA Ronald J. Vessey, Washington State DOT (retired), Normandy Park, WA Kathryn Wochinger, NHTSA Liaison

BTSCRP Research Report 3: Behavioral Traffic Safety Messaging on Variable Message Signs provides an evidence-based approach to help guide behavioral traffic safety (BTS) message design and display on variable message signs (VMS). The research team conducted a systematic review of current practices regarding BTS design and display on VMS; per- formed human factors testing of BTS message displays on VMS; developed recommen- dations for the design and display of BTS messages on VMS; and developed a guide for the use of VMS to deliver BTS messages to motorists. This guide will be of interest to state high- way safety offices, state departments of transportation, and other stakeholders concerned with improving the design and display of BTS messages on VMS. VMS (also sometimes referred to as changeable, electronic, or dynamic message signs) are used to provide real-time traffic information to drivers while en route to their destina- tion. Many agencies also use these signs to display BTS messages when the signs are not being used to display other traffic information. These types of messages encourage safe driving behaviors (e.g., wearing seat belts, not drinking and driving, etc.). Currently, the ways in which agencies develop and display BTS messages on VMS vary widely across the country. More importantly, little guidance is currently available as to how BTS messages should be designed and presented on VMS. Poorly designed or con- fusing BTS messages could attract too much visual and cognitive attention by the driver and potentially reduce safety. It would be useful to determine what constitutes effective practices regarding the design and display of BTS messages and to develop implementation guidelines on BTS message design and display that is useful to VMS operating agencies. In BTSCRP Project BTS-02, Texas A&M Transportation Institute was asked to (1) review current practices regarding BTS message design and display on VMS; (2) conduct human factors testing of BTS message displays on VMS; (3) develop recommendations for design and display of BTS messages on VMS; and (4) develop a guide for the use of VMS to deliver BTS messages to motorists. F O R E W O R D By Richard A. Retting Staff Officer Transportation Research Board

S-1 Summary P A R T 1 Guide 1-3 Chapter 1 Introduction 1-3 Need for the Guide 1-4 Organization of the Guide 1-5 Chapter 2 Fundamentals of BTS Messaging 1-5 Basic Concepts of BTS Messaging 1-5 Defining the Execution Strategy of a BTS Message 1-8 Chapter 3 VMS Message Design and Operating Principles for BTS Messages 1-8 Understanding Drivers’ Capabilities for Reading VMS 1-8 FHWA Ruling Regarding BTS Messages on VMS 1-10 Design Criteria for BTS Messages on VMS 1-13 Chapter 4 BTS Message Display Guidelines for VMS 1-15 Part 1 References A-1 Appendix A Example VMS-Formatted BTS Message Phases by Traffic Safety Topic P A R T 2 Conduct of Research 2-3 Chapter 5 Background 2-3 Problem Statement 2-4 Previous Research 2-7 Project Objectives 2-9 Chapter 6 Current Practices Regarding BTS Message Design and Display on VMS 2-9 BTS Message Creation and Approval 2-10 BTS Message Design Policies 2-10 BTS Message Display Criteria 2-12 Characteristics of BTS Messages Displayed on VMS 2-14 Compliance with VMS Message Design Principles C O N T E N T S

2-16 Chapter 7 Human Factors Testing of BTS Message Displays on VMS 2-16 Introduction 2-16 Study Objectives 2-16 Study Methodology 2-20 Results 2-27 Summary 2-29 Chapter 8 Conclusions and Recommendations 2-29 Conclusions 2-30 Recommendations 2-32 Part 2 References B-1 Appendix B Agency Survey Questions C-1 Appendix C Raw Human Factors Study Results Note: Photographs, figures, and tables in this report may have been converted from color to grayscale for printing. The electronic version of the report (posted on the web at www.nap.edu) retains the color versions.