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TRANSPORTATION RESEARCH BOARD WASHINGTON, D.C. 2014 www.TRB.org The Second S T R A T E G I C H I G H W A Y R E S E A R C H P R O G R A M REPORT S2-L14-RW-1 Effectiveness of Different Approaches to Disseminating Traveler Information on Travel Time Reliability Beverly Kuhn, laura higgins, alicia nelson, Melisa Finley, and gerald ullMan Texas A&M Transportation Institute College Station, Texas susan chrysler University of Iowa Iowa City, Iowa Karl Wunderlich and vaishali shah Noblis, Inc. Washington, D.C. conrad dudeK Dudek & Associates Bryan, Texas
Subject Areas Highways Operations and Traffic Management Passenger Transportation Public Transportation Safety and Human Factors
SHRP 2 Reports Available by subscription and through the TRB online bookstore: www.TRB.org/bookstore Contact the TRB Business Office: 202-334-3213 More information about SHRP 2: www.TRB.org/SHRP2 SHRP 2 Report S2-L14-RW-1 ISBN: 978-0-309-27305-3 © 2014 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 copy- right to any previously published or copyrighted material used herein. The second Strategic Highway Research Program grants permission to repro- duce 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, or FHWA endorsement of a particular prod- uct, method, or practice. It is expected that those reproducing material in this document for educational and not-for-profit purposes will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from SHRP 2. Note: SHRP 2 report numbers convey the program, focus area, project number, and publication format. Report numbers ending in âwâ are published as web documents only. Notice The project that is the subject of this report was a part of the second Strategic Highway Research Program, conducted by the Transportation Research Board with the approval of the Governing Board of the National Research Council. The members of the technical committee selected to monitor this project and review this report were chosen for their special competencies and with regard for appropriate balance. The report was reviewed by the technical committee and accepted for publication according to procedures established and overseen by the Transportation Research Board and approved by the Governing Board of the National Research Council. 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 Research Council, or the program sponsors. The Transportation Research Board of the National Academies, the National Research Council, and the sponsors of the second Strategic Highway Research Program do not endorse products or manufacturers. Trade or manufacturersâ names appear herein solely because they are considered essential to the object of the report. The Second Strategic Highway Research Program Americaâs highway system is critical to meeting the mobility and economic needs of local communities, regions, and the nation. Developments in research and technologyâsuch as advanced materials, communications technology, new data collection tech- nologies, and human factors scienceâoffer a new opportunity to improve the safety and reliability of this important national resource. Breakthrough resolution of significant transportation problems, however, requires concentrated resources over a short time frame. Reflecting this need, the second Strategic Highway Research Program (SHRP 2) has an intense, large-scale focus, integrates multiple fields of research and technology, and is fundamentally different from the broad, mission-oriented, discipline-based research programs that have been the mainstay of the highway research industry for half a century. The need for SHRP 2 was identified in TRB Special Report 260: Strategic Highway Research: Saving Lives, Reducing Congestion, Improving Quality of Life, published in 2001 and based on a study sponsored by Congress through the Transportation Equity Act for the 21st Century (TEA-21). SHRP 2, modeled after the first Strategic Highway Research Program, is a focused, time- constrained, management-driven program designed to com- plement existing highway research programs. SHRP 2 focuses on applied research in four areas: Safety, to prevent or reduce the severity of highway crashes by understanding driver behavior; Renewal, to address the aging infrastructure through rapid design and construction methods that cause minimal disruptions and produce lasting facilities; Reliability, to reduce congestion through incident reduction, management, response, and mitigation; and Capacity, to integrate mobility, economic, environmental, and community needs in the planning and designing of new trans- portation capacity. SHRP 2 was authorized in August 2005 as part of the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU). The program is managed by the Transportation Research Board (TRB) on behalf of the National Research Council (NRC). SHRP 2 is conducted under a memo- randum of understanding among the American Association of State Highway and Transportation Officials (AASHTO), the Federal Highway Administration (FHWA), and the National Academy of Sciences, parent organization of TRB and NRC. The program provides for competitive, merit-based selection of research contractors; independent research project oversight; and dissemination of research results.
The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. On the authority of the charter granted to it by Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Ralph J. Cicerone is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achieve- ments of engineers. Dr. C. D. (Dan) Mote, Jr., is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, on its own initiative, to identify issues of medical care, research, and education. Dr. Victor J. Dzau is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academyâs purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Ralph J. Cicerone and Dr. C. D. (Dan) Mote, Jr., are chair and vice chair, respectively, of the National Research Council. The Transportation Research Board is one of six major divisions of the National Research Council. The mission of the Transportation Research Board is to provide leadership in transportation innovation and progress through research and information exchange, conducted within a setting that is objective, interdisci- plinary, and multimodal. The Boardâs varied activities annually engage about 7,000 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. The program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transporta- tion, and other organizations and individuals interested in the development of transportation. www.TRB.org www.national-academies.org
Acknowledgments This work was sponsored by the Federal Highway Administration in cooperation with the American Asso- ciation of State Highway and Transportation Officials. It was conducted in the second Strategic Highway Research Program (SHRP 2), which is administered by the Transportation Research Board of the National Academies. The project was managed by Abdelmename Hedhli, Visiting Professional for SHRP 2 Reliability. The research reported was performed by Texas A&M Transportation Institute, supported by Noblis, Inc., and Dudek & Associates. Beverly Kuhn, Texas A&M Transportation Institute, was the principal investigator along with Susan Chrysler, University of Iowa, when she was with Texas A&M Transportation Institute. The other authors of the report are Laura Higgins, Alicia Nelson, Melisa Finley, and Gerald Ullman of Texas A&M Transportation Institute; Karl Wunderlich and Vaishali Shah of Noblis, Inc.,; and Conrad Dudek of Dudek & Associates. The authors acknowledge the contributions to this research from Katie Connell, Sarah Hammond, Brenda Manak, Kristine Miller, Lisa Minjares, Lisa Patke, Roma Stevens, Sandra Stone, Luann Theiss, Nada Trout, Brooke Ullman, and Christine Yager of Texas A&M Transportation Institute and Jim Larkin of Noblis, Inc. sHRP 2 stAFF Ann M. Brach, Director Stephen J. Andrle, Deputy Director Neil J. Pedersen, Deputy Director, Implementation and Communications Cynthia Allen, Editor Kenneth Campbell, Chief Program Officer, Safety JoAnn Coleman, Senior Program Assistant, Capacity and Reliability Eduardo Cusicanqui, Financial Officer Richard Deering, Special Consultant, Safety Data Phase 1 Planning Shantia Douglas, Senior Financial Assistant Charles Fay, Senior Program Officer, Safety Carol Ford, Senior Program Assistant, Renewal and Safety Jo Allen Gause, Senior Program Officer, Capacity James Hedlund, Special Consultant, Safety Coordination Alyssa Hernandez, Reports Coordinator Ralph Hessian, Special Consultant, Capacity and Reliability Andy Horosko, Special Consultant, Safety Field Data Collection William Hyman, Senior Program Officer, Reliability Linda Mason, Communications Officer Reena Mathews, Senior Program Officer, Capacity and Reliability Matthew Miller, Program Officer, Capacity and Reliability Michael Miller, Senior Program Assistant, Capacity and Reliability David Plazak, Senior Program Officer, Capacity and Reliability Rachel Taylor, Senior Editorial Assistant Dean Trackman, Managing Editor Connie Woldu, Administrative Coordinator
F o r e w o r d Abdelmename Hedhli, SHRP 2 Visiting Professional, Reliability Travel time reliability can be defined as consistency of travel time over time. The primary goal of SHRP 2 Reliability research is to improve the reliability of highway travel times by mitigating the effects of events that cause travel times to fluctuate unpredictably. Seven sources of unreliable travel times are now generally accepted: traffic incidents, work zones, demand fluctuations, special events, traffic control devices, weather, and inadequate base capacity. A key component to addressing the reliability issue related to urban mobility is conveying this reliability-related information to system users so that they can make informed decisions about their travel. The goal of the SHRP 2 L14 project, Effectiveness of Different Approaches to Disseminating Traveler Information on Travel Time Reliability, is to examine what com- bination of words, numbers, and other features of user information messages, along with communications methods and technology platforms, best communicate information about travel time and reliability to travelers so they can make optimal travel choices from their point of view, such as whether to take a trip, departure time, mode choice, and route choice. This final report documents the research conducted as part the SHRP 2 L14 project. One of the main work products from the L14 project is the Lexicon for Conveying Travel Time Reliability Information, which offers recommendations to system operators on appropri- ate ways to provide travel time reliability information to travelers so that the information is most likely to be understood and used by travelers to influence their travel choices. The research team identified several key elements of a lexicon entry that were deemed necessary to completely present each term and how it might be used within the transportation com- munity. One purpose of this final report is to describe the process that led to the develop- ment of the lexicon. The research began with a literature review to document existing practices and lessons learned regarding the communication of both travel and non-travel-related reliability information. The team then focused on conducting expert interviews and a technology and innovation scan to further examine the state of the practice in communicating information to travelers. The team also conducted a series of human factors experiments, including focus groups and surveys, to assess travelersâ comprehension and preferences for various reliability-related words and phrases. Finally, two laboratory experiments developed a utility function for travel time reliability information by observing participantsâ use of reliability information during simulated com- mute trips and soliciting their opinions about the monetary value of that information. The lexicon was developed as the final task of this project.
C o N T e N T S 1 Executive Summary 1 Travel Time Reliability 3 Reliability Terminology: Human Factors Experiments 4 Lexicon Development 5 Utility Functions and User Behavior 7 Study Limitations 7 Potential Next Steps 9 cHAPteR 1 Introduction 9 Background 9 Travel Time Reliability Information 11 Informational Delivery Challenges 11 Scope and Purpose of Technical Report 11 Project Evolution 15 cHAPteR 2 Literature Review 15 Travel Time Reliability Metrics 17 Importance of Travel Time Reliability 18 Travel Time Information: State of the Practice 21 cHAPteR 3 Expert Interviews 21 Design of Telephone Interview 21 Telephone Interview Participants 21 Telephone Interview Results 25 cHAPteR 4 Technology and Innovation Scan 25 Introduction and Context 26 Underlying Technology Trends: Better Data to Come 30 Innovative Media for Traveler Information Users 34 Traveler Information Market Participants 37 Outlook for Traveler Reliability Information 40 cHAPteR 5 Developed Avenues of Investigation 40 Key Research Issues 43 cHAPteR 6 Focus Groups 43 Script Development 46 Participants 46 Results Summary 47 Lexicon Information
49 cHAPteR 7 Usability Surveys 49 Study Locations 49 Study Participants 50 Computer Survey 71 cHAPteR 8 Open-Ended Survey 71 Research Method 73 Results 83 Conclusions 84 Recommendations 85 cHAPteR 9 Travel Behavior Laboratory Experiment 86 Background 86 Literature Review 87 Experiment Plan 90 Pre- and Post-Experiment Survey Findings 97 Experimental Results 102 Application of Results in Travel Utility Functions 103 Conclusions and Next Steps 105 cHAPteR 10 Enhanced Laboratory Experiment 105 Experiment Scope and Hypotheses 106 Experimental Plan 111 Pre-Experiment Survey Findings 114 Experiment 1 Findings: Effectiveness and Valuation of Reliability Terms for Unfamiliar Trips 125 Experiment 2 Findings: Reliability Data Expedites Learning Curve for Trip Familiarity 127 Post-Experiment Survey Findings 130 Conclusions and Looking Forward 132 cHAPteR 11 Lexicon Development 132 Frequently Used Terms 133 Terminology Assessment 137 Lexicon Format 138 Limitations of Lexicon Information 138 Travel Time Reliability Lexicon 146 cHAPteR 12 Final Remarks 146 Study Limitations 147 Key Findings on Travel Time Reliability Terminology 147 Key Study Observations on User Behavior 148 Potential Next Steps 151 References 155 Glossary 156 Appendix A. General Literature Review 167 Appendix B. Telephone Interview Guide for Expert Interviews 172 Appendix C. Detailed Focus Group Summary 182 Appendix D. Computer Survey Questions and Results Tables
211 Appendix E. Open-Ended Survey Materials 218 Appendix F. Travel Behavior Laboratory Experiment Documentation 228 Appendix G. Supplemental Figures from Travel Behavior Laboratory Experiment Pre-Survey 232 Appendix H. Enhanced Laboratory Experiment Documentation 255 Appendix I. Supplemental Figures from Enhanced Laboratory Experiment Results
