TRANSPORTATION RESEARCH Number E-C194 March 2015 Literature Searches and Literature Reviews for Transportation Research Projects How to Search, Where to Search, and How to Put It All Together: Current Practices TRANSPORTATION RESEARCH BOARD 2015 EXECUTIVE COMMITTEE OFFICERS Chair: Daniel Sperling, Professor of Civil Engineering and Environmental Science and Policy; Director, Institute of Transportation Studies, University of California, Davis Vice Chair: James M. Crites, Executive Vice President of Operations, Dallas–Fort Worth International Airport, Texas Division Chair for NRC Oversight: Susan Hanson, Distinguished University Professor Emerita, School of Geography, Clark University, Worcester, Massachusetts Executive Director: Neil J. Pedersen, Transportation Research Board TRANSPORTATION RESEARCH BOARD 2014–2015 TECHNICAL ACTIVITIES COUNCIL Chair: Daniel S. Turner, Emeritus Professor of Civil Engineering, University of Alabama, Tuscaloosa Technical Activities Director: Mark R. Norman, Transportation Research Board Peter M. Briglia, Jr., Consultant, Seattle, Washington, Operations and Preservation Group Chair Alison Jane Conway, Assistant Professor, Department of Civil Engineering, City College of New York, New York, Young Members Council Chair Mary Ellen Eagan, President and CEO, Harris Miller Miller and Hanson, Inc., Burlington, Massachusetts, Aviation Group Chair Barbara A. Ivanov, Director, Freight Systems, Washington State Department of Transportation, Olympia, Freight Systems Group Chair Paul P. Jovanis, Professor, Pennsylvania State University, University Park, Safety and Systems Users Group Chair Thomas J. Kazmierowski, Senior Consultant, Golder Associates, Inc., Mississauga, Ontario, Canada, Design and Construction Group Chair Mark S. Kross, Consultant, Jefferson City, Missouri, Planning and Environment Group Chair Hyun-A C. Park, President, Spy Pond Partners, LLC, Arlington, Massachusetts, Policy and Organization Group Chair Harold R. (Skip) Paul, Director, Louisiana Transportation Research Center, Louisiana Department of Transportation and Development, Baton Rouge, State DOT Representative Stephen M. Popkin, Director, Safety Management and Human Factors, Office of the Assistant Secretary of Transportation for Research and Technology, Volpe National Transportation Systems Center, Cambridge, Massachusetts, Rail Group Chair James S. Thiel, Consultant, Madison, Wisconsin, Legal Resources Group Chair Thomas H. Wakeman III, Research Professor, Stevens Institute of Technology, Hoboken, New Jersey, Marine Group Chair David C. Wilcock, Vice President and National Practice Leader for Rail and Transit, Michael Baker, Jr., Inc., Norwood, Massachusetts, Public Transportation Group Chair TRANSPORTATION RESEARCH CIRCULAR E-C194 Literature Searches and Literature Reviews for Transportation Research Projects How to Search, Where to Search, and How to Put It All Together: Current Practices Prepared by Andrea Avni, Paul Burley, Patrick Casey, John Cherney, Leighton Christiansen, Janet Saunders Daly, Rita Evans, David Jared, Greg Landgraf, Andrew Meier, Jane Minotti, Barbara Post, Birgitta Sandstedt, Roberto Sarmiento, Susan Sillick, Bob Sweet, Michael Wendt, Ken Winter, and Hong Yu For the Conduct of Research Committee Library and Information Science for Transportation Committee Transportation Research Board March 2015 Transportation Research Board 500 Fifth Street, NW Washington, DC 20001 www.TRB.org TRANSPORTATION RESEARCH CIRCULAR E-C194 The Transportation Research Board is a unit of the National Research Council, a private, nonprofit institution that is the principal operating agency of the National Academy of Sciences and the National Academy of Engineering. Under a congressional charter granted to the National Academy of Sciences, the National Research Council provides scientific and technical advice to the government, the public, and the scientific and engineering communities. The Transportation Research Board is distributing this Circular to make the information contained herein available for use by individual practitioners in state and local transportation agencies, researchers in academic institutions, and other members of the transportation research community. The information in this Circular was taken directly from the submissions of the authors. This document is not a report of the National Research Council or of the National Academy of Sciences. Standing Committee on Conduct of Research Jason Bittner, Barbara Harder, Cochairs Michael Bonini David Jared Steve Phillips Patrick Casey Matthew Klein Martin Pietrucha Dae-Yeon Cho Mark Morvant Karel Pospisil Rick Collins Shashi Nambisan Linda Preisen James Dockstader Leni Oman John Sangster Anne Ellis Melissa Paciulli Susan Sillick Monique Evans Ned Parrish Jarrett Stoltzfus Hau Hagedorn Neil Paulley Daniel Yeh Standing Committee on Library and Information Science for Transportation Roberto Sarmiento, Chair Matthew Barrett David Jared Birgitta Sandstedt Paul Burley Kendra Levine Susan Sillick John Cherney Arlene Mathison Bob Sweet Robert Cullen Lynn Matis Dennis van den Braak Rita Evans Andrew Meier Kenneth Winter Sheila Hatchell Mary Moulton Hong Yu Kenita Honesty Stephen Pepin Lisa Zilinski Christopher Pringle Minnesota Department of Transportation Linda Taylor, Research Director TRB Staff James W. Bryant, Jr., Senior Program Officer, Maintenance and Preservation Engineer Joanice L. Johnson, Associate Program Officer Transportation Research Board 500 Fifth Street, NW Washington, DC 20001 www.TRB.org Lea Camarda, Production Editor; Jennifer Correro, Proofreading; Jennifer J. Weeks, Layout Preface esearch projects sponsored by state departments of transportation (DOTs) routinely require a Rliterature review as part of the research effort. The literature review is a critical portion of the research process in any field of inquiry and an important component of the final research report. For the researcher, a literature review helps to clarify the scope of the research project by creating a narrative of what is and is not known in the field and where there are areas of dispute. For the customer of the research and other readers, the review also provides valuable context, establishes the researcher’s expertise, and relates the findings of the project to what is already known. However, investigators tasked with developing literature reviews for transportation research projects may not always be aware of the importance of the literature review or have an adequate understanding of the necessary steps for producing a high-quality review. This may lead to the submission of literature reviews that are incomplete, unfocused, poorly explained, or otherwise inadequate. Minnesota DOT Research Engineer Alan Rindels raised this issue during the 92nd Annual Meeting of the Transportation Research Board, recounting his own experience receiving inadequate literature reviews. He presented his concerns to both the Standing Committee on Conduct of Research (CoR) and the Standing Committee on Library and Information Science for Transportation (LIST) and requested the committees’ assistance in addressing the problem. A working group, comprised of members from both committees, identified four components to address this issue: 1. How to conduct literature searches; 2. Where to search for transportation information; 3. How to put it all together as a quality literature review; and 4. Definitions for related terms. LIST Chair Roberto Sarmiento led work on the first two components of the project with teams from LIST and the Transportation Division of the Special Libraries Association (SLA). Susan Sillick, CoR member and LIST co–research coordinator, led work on the third and fourth components. Together the two coordinated the entire project. For the third component, Minnesota DOT Research Director Linda Taylor supported the preparation of a synthesis of accepted practices on writing a literature review, carried out by consultant CTC & Associates, LLC. This e-circular is the result of a 2-year collaborative effort by more than 50 individuals. The publication is aimed at all transportation researchers, including university investigators, graduate students, consultants, and practitioners at state and federal transportation agencies. The e-circular also will be useful to sponsors of research when conducting initial literature searches and evaluating literature reviews to determine the quality of the products received. iii Contents PART I: LITERATURE SEARCHES—HOW TO SEARCH ..................................................1 Janet Saunders Daly, Andrew Meier, Kenneth Winter, and Hong Yu What Is a Literature Search? ......................................................................................................1 Why Conduct a Literature Search? ............................................................................................2 Six Steps of a Literature Search .................................................................................................2 Step 1: Define the Search Topic and Scope .........................................................................2 Step 2: Choose the Resources to Search ..............................................................................4 Step 3: Choose Search Terms ..............................................................................................7 Step 4: Compile the Search Strategy and Run the Search ...................................................8 Step 5: Review the Search Results.....................................................................................14