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S2-L14-RW-2 Lexicon for Conveying Travel Time Reliability Information 028343 SHRP2 L14 Lexicon.indd 1 8/8/14 12:19 PM
TRANSPORTATION RESEARCH BOARD 2014 EXECUTIVE COMMITTEE* OFFICERS Chair: Kirk T. Steudle, Director, Michigan Department of Transportation, Lansing Vice Chair: Daniel Sperling, Professor of Civil Engineering and Environmental Science and Policy; Director, Institute of Transportation Studies, University of California, Davis Executive Director: Robert E. Skinner, Jr., Transportation Research Board MEMBERS Victoria A. Arroyo, Executive Director, Georgetown Climate Center, and Visiting Professor, Georgetown University Law Center, Washington, D.C. Scott E. Bennett, Director, Arkansas State Highway and Transportation Department, Little Rock Deborah H. Butler, Executive Vice President, Planning, and CIO, Norfolk Southern Corporation, Norfolk, Virginia (Past Chair, 2013) James M. Crites, Executive Vice President of Operations, DallasâFort Worth International Airport, Texas Malcolm Dougherty, Director, California Department of Transportation, Sacramento A. Stewart Fotheringham, Professor and Director, Centre for Geoinformatics, School of Geography and Geosciences, University of St. Andrews, Fife, United Kingdom John S. Halikowski, Director, Arizona Department of Transportation, Phoenix Michael W. Hancock, Secretary, Kentucky Transportation Cabinet, Frankfort Susan Hanson, Distinguished University Professor Emerita, School of Geography, Clark University, Worcester, Massachusetts Steve Heminger, Executive Director, Metropolitan Transportation Commission, Oakland, California Chris T. Hendrickson, Duquesne Light Professor of Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania Jeffrey D. Holt, Managing Director, Bank of Montreal Capital Markets, and Chairman, Utah Transportation Commission, Huntsville, Utah Gary P. LaGrange, President and CEO, Port of New Orleans, Louisiana Michael P. Lewis, Director, Rhode Island Department of Transportation, Providence Joan McDonald, Commissioner, New York State Department of Transportation, Albany Abbas Mohaddes, President and CEO, Iteris, Inc., Santa Ana, California Donald A. Osterberg, Senior Vice President, Safety and Security, Schneider National, Inc., Green Bay, Wisconsin Steven W. Palmer, Vice President of Transportation, Loweâs Companies, Inc., Mooresville, North Carolina Sandra Rosenbloom, Professor, University of Texas, Austin (Past Chair, 2012) Henry G. (Gerry) Schwartz, Jr., Chairman (retired), Jacobs/Sverdrup Civil, Inc., St. Louis, Missouri Kumares C. Sinha, Olson Distinguished Professor of Civil Engineering, Purdue University, West Lafayette, Indiana Gary C. Thomas, President and Executive Director, Dallas Area Rapid Transit, Dallas, Texas Paul Trombino III, Director, Iowa Department of Transportation, Ames Phillip A. Washington, General Manager, Regional Transportation District, Denver, Colorado EX OFFICIO MEMBERS Thomas P. Bostick, (Lt. General, U.S. Army), Chief of Engineers and Commanding General, U.S. Army Corps of Engineers, Washington, D.C. Alison J. Conway, Assistant Professor, Department of Civil Engineering, City College of New York, New York, and Chair, TRB Young Members Council Anne S. Ferro, Administrator, Federal Motor Carrier Safety Administration, U.S. Department of Transportation David J. Friedman, Acting Administrator, National Highway Traffic Safety Administration, U.S. Department of Transportation LeRoy Gishi, Chief, Division of Transportation, Bureau of Indian Affairs, U.S. Department of the Interior, Washington, D.C. John T. Gray II, Senior Vice President, Policy and Economics, Association of American Railroads, Washington, D.C. Michael P. Huerta, Administrator, Federal Aviation Administration, U.S. Department of Transportation Paul N. Jaenichen, Sr., Acting Administrator, Maritime Administration, U.S. Department of Transportation Therese W. McMillan, Acting Administrator, Federal Transit Administration Michael P. Melaniphy, President and CEO, American Public Transportation Association, Washington, D.C. Gregory Nadeau, Acting Administrator, Federal Highway Administration, U.S. Department of Transportation Cynthia L. Quarterman, Administrator, Pipeline and Hazardous Materials Safety Administration, U.S. Department of Transportation Peter M. Rogoff, Under Secretary for Policy, U.S. Department of Transportation Craig A. Rutland, U.S. Air Force Pavement Engineer, Air Force Civil Engineer Center, Tyndall Air Force Base, Florida Joseph C. Szabo, Administrator, Federal Railroad Administration, U.S. Department of Transportation Barry R. Wallerstein, Executive Officer, South Coast Air Quality Management District, Diamond Bar, California Gregory D. Winfree, Assistant Secretary for Research and Technology, Office of the Secretary, U.S. Department of Transportation Frederick G. (Bud) Wright, Executive Director, American Association of State Highway and Transportation Officials, Washington, D.C. Paul F. Zukunft, (Adm., U.S. Coast Guard), Commandant, U.S. Coast Guard, U.S. Department of Homeland Security * Membership as of August 2014. 028343 SHRP2 L14 Lexicon.indd 2 8/8/14 12:19 PM
THE SECOND STRATEGIC HIGHWAY RESEARCH PROGRAM 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 TRANSPORTATION RESEARCH BOARD Washington, D.C. 2014 www.TRB.org Lexicon for Conveying Travel Time Reliability Information SHRP 2 Report S2-L14-RW-2 028343 SHRP2 L14 Lexicon.indd 1 8/8/14 12:19 PM
SUBJECT AREAS Highways Operations and Traffic Management Passenger Transportation Public Transportation Safety and Human Factors 028343 SHRP2 L14 Lexicon.indd 2 8/8/14 12:19 PM
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 technologies, 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 mul- tiple 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 high- way 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, pub- lished in 2001 and based on a study sponsored by Congress through the Transportation Equity Act for the 21st Cen- tury (TEA-21). SHRP 2, modeled after the first Strategic Highway Research Program, is a focused, time-constrained, management-driven program designed to complement 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 infrastruc- ture through rapid design and construction methods that cause minimal disruptions and produce lasting facilities; Reliability, to reduce congestion through incident reduc- tion, management, response, and mitigation; and Capacity, to integrate mobility, economic, environmental, and com- munity 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 pro- gram is managed by the Transportation Research Board (TRB) on behalf of the National Research Council (NRC). SHRP 2 is conducted under a memorandum of understand- ing among the American Association of State Highway and Transportation Officials (AASHTO), the Federal Highway Administration (FHWA), and the National Academy of Sci- ences, 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. SHRP 2 Report S2-L14-RW-2 ISBN: 978-0-309-27307-7 © 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 pub- lishers or persons who own the copyright to any previously published or copyrighted material used herein. The second Strategic Highway Research Program 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, or FHWA endorsement of a particular product, method, or practice. It is expected that those reproducing material in this document for educa- tional and not-for-profit purposes will give appropriate ac- knowledgment 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 num- bers 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 moni- tor this project and to review this report were chosen for their special competencies and with regard for appropriate balance. The report was reviewed by the technical commit- tee 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 re- search and are not necessarily those of the Transportation Research Board, the National Research Council, or the pro- gram sponsors. The Transportation Research Board of the National Acad- emies, the National Research Council, and the sponsors of the second Strategic Highway Research Program do not en- dorse products or manufacturers. Trade or manufac turersâ names appear herein solely because they are considered essen tial to the object of the report. 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 028343 SHRP2 L14 Lexicon.indd 3 8/8/14 12:19 PM
The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished schol- ars 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 the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and techni- cal 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 advis- ing 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. 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 ser- vices 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, upon 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 Sci- ences 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. 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, inter- disciplinary, and multimodal. The Boardâs varied activities annually engage about 7,000 engineers, sci- entists, 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 Transportation, and other organizations and individuals interested in the development of transportation. www.TRB.org www.national-academies.org 028343 SHRP2 L14 Lexicon.indd 4 8/8/14 12:19 PM
SHRP 2 STAFF Ann M. Brach, Director Stephen J. Andrle, Deputy Director Neil J. Pedersen, Deputy Director, Implementation and Communications James Bryant, Senior Program Officer, Renewal Kenneth Campbell, Chief Program Officer, Safety JoAnn Coleman, Senior Program Assistant, Capacity and Reliability Eduardo Cusicanqui, Financial Officer Walter Diewald, Senior Program Officer, Safety Jerry DiMaggio, Implementation Coordinator Shantia Douglas, Senior Financial Assistant Charles Fay, Senior Program Officer, Safety Carol Ford, Senior Program Assistant, Renewal and Safety Elizabeth Forney, Assistant Editor Jo Allen Gause, Senior Program Officer, Capacity Rosalind Gomes, Accounting/Financial Assistant Abdelmename Hedhli, Visiting Professional 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 Michael Marazzi, Senior Editorial Assistant 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 Monica Starnes, Senior Program Officer, Renewal Charles Taylor, Special Consultant, Renewal Onno Tool, Visiting Professional Dean Trackman, Managing Editor Connie Woldu, Administrative Coordinator 028343 SHRP2 L14 Lexicon.indd 5 8/8/14 12:19 PM
This work was sponsored by the Federal Highway Administration in cooperation with the American Association of State Highway and Transportation Officials. It was con- ducted in the second Strategic Highway Research Program, which is administered by the Transportation Research Board of the National Academies. The project was man- aged by Abdelmename Hedhli, Visiting Professional for SHRP 2 Reliability. The research reported on was performed by Texas A&M Transportation Institute, supported by Noblis, Inc., and Dudek & Associates. Beverly Kuhn, Texas A&M Trans- portation Institute, was the principal investigator 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 contribu- tions 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 from Jim Larkin of Noblis, Inc. ACKNOWLEDGMENTS 028343 SHRP2 L14 Lexicon.indd 6 8/8/14 12:19 PM
FOREWORD Travel time reliability can be defined as consistency of travel time over time. The pri- mary 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 un- predictably. 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 reliability-related information to system users so that they can make informed decisions about their travel. The goal of the SHRP 2 L14 project, Effective- ness of Different Approaches to Disseminating Traveler Information on Travel Time Reliability, is to examine what combination of words, numbers, and other features of user information messages, along with communications methods and technology plat- forms, best communicate information about travel time and reliability to travelers so that 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. The lexicon is one of the main L14 project work products. It offers recommenda- tions to system operators on appropriate ways to provide travel time reliability infor- mation to travelers so that the information is most likely to be understood and used by travelers to influence their travel choices. On the basis of the results of human factors studies and current traffic engineer- ing practices regarding communicating to drivers, recommendations were made in the lexicon for using the following terms related to travel time reliability: 95th percentile, arrival time, average travel time, buffer time, delay time, departure time, free-flow travel time, peak travel time, planning time, planning time index, recommended depar- ture time, recommended route, and reliability. There is also input from a literature Abdelmename Hedhli SHRP 2 Visiting Professional, Reliability 028343 SHRP2 L14 Lexicon.indd 7 8/8/14 12:19 PM
review, expert interviews, and a technology and innovation scan done as part of the research project. For each of the travel time reliability terms listed, the lexicon includes a technical travel time reliability term, the definition of the term or concept within the reliability framework, a description of when or for what purpose an agency might use the term, and recommendations for terminology, phrases, or graphics to be used, in order of preference. Finally, the lexicon identifies appropriate media and technology interfaces for each listed term, phrase, or graphic. 028343 SHRP2 L14 Lexicon.indd 8 8/8/14 12:19 PM
