Background and Summary of a Guide for Roundabouts (2023)

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NCHRP Web-Only Document 347 Background and Summary of a Guide for Roundabouts Kittelson & Associates, Inc. Portland, OR Sunrise Transportation Strategies, LLC Portland, OR Texas A&M Transportation Institute College Station, TX Kimley-Horn and Associates, Inc. Peachtree Corners, GA Accessible Design for the Blind, LLC Fairbanks, AK Quality Counts, LLC Tigard, OR Conduct of Research Report for NCHRP Project 03-130 Submitted September 2022 © 2023 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. NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed, and implementable research is the most effective way to solve many problems facing state departments of transportation (DOTs) 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, under Agreement No. 693JJ31950003. 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. DISCLAIMER The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research. They 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, and the sponsors of the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturers’ names appear herein solely because they are considered essential to the object of the report. The information contained in this document was taken directly from the submission of the author(s). This material has not been edited by TRB.

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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 NCHRP WEB-ONLY DOCUMENT 347 Christopher J. Hedges, Director, Cooperative Research Programs Waseem Dekelbab, Deputy Director, Cooperative Research Programs, and Manager, National Cooperative Highway Research Program Amir Hanna, Senior Program Officer Emily Griswold, Program Coordinator Natalie Barnes, Director of Publications Heather DiAngelis, Associate Director of Publications Jennifer Correro, Assistant Editor NCHRP PROJECT 03-130 PANEL Field of Traffic—Area of Operations and Control Michael J. Dugas, New Hampshire Department of Transportation (formerly), Concord, NH (Chair) Asma Ali, T3 Design Corporation, Fairfax, VA Christina D. Barry, Georgia Department of Transportation, Atlanta, GA Stephen A. Bass, Kansas Department of Transportation, Topeka, KS Richard B. Crossler-Laird, Oregon Department of Transportation, Salem, OR Rachel S. Price, Roundabotix, San Diego, CA Eugene Robert Russell, Sr., Kansas State University, Manhattan, KS Brian J. Walsh, Washington State Department of Transportation, Olympia, WA Hillary Nicole Isebrands, FHWA Liaison Bernardo B. Kleiner, TRB Liaison ACKNOWLEDGMENTS This document was prepared under the National Cooperative Highway Research Program (NCHRP) Project 03-130, “Guide for Roundabouts,” and is associated with NCHRP Research Report 1043: Guide for Roundabouts (Guide). This document provides background on the development of the Guide, which provides guidance for planning, designing, and implementing roundabouts based on integrating user needs within the widest array of project contexts. The Guide expands upon a performance-based approach that is centered on developing project solutions to best meet and balance each user’s needs. Kittelson & Associates, Inc. (Kittelson) served as the prime contractor. Brian Ray, Sunrise Transportation Strategies, LLC (formerly with Kittelson & Associates, Inc.), served as the Principal Investigator. Lee Rodegerdts, Kittelson, initiated the project as the Principal Investigator and continued to serve as a key author for Guide content. Julia Knudsen provided invaluable project coordination contributing to the Guide’s development. In addition, the Kittelson team consisted of Michael Alston, Alek Pochowski, Krista Purser, Justin Bansen, Ed Myers, and Gene Hawkins. Subcontractors provided valuable contributions to research tasks and Guide content and include Mark Lenters and Jay VonAhsen, Kimley-Horn Associates; Janet Barlow and Beezy Bentzen, Accessible Design for the Blind, LLC; and Marcus Brewer, Texas A&M University, Texas Transportation Institute. Quality Counts, LLC supported data collection for research tasks that informed Guide content. Guide development was supported by Ralph Bentley, Mindy Weber, Dimitryan Shadrin, Caleb Cox, and Anthea Fernandes of Kittelson. Andrew Ooms, Andy Duerr, Liz Byrom, Aditya Inamdar, Radu Nan, Margaret Kent, and Liz Flanagan, (Kittelson) contributed to Guide content, assisted with graphical information, and conducted early project tasks.

iv Table of Contents Summary ..................................................................................................................................................... 1 Research Report Organization ............................................................................................................. 1 Purpose .................................................................................................................................................... 1 Findings and Application ..................................................................................................................... 1 Conclusions ............................................................................................................................................. 2 Background .............................................................................................................................. 3 Research Approach ................................................................................................................. 4 Findings and Applications .................................................................................................... 5 3.1. Literature Assembly ....................................................................................................................... 5 3.2. Survey of User Feedback ................................................................................................................ 5 3.3. Designing for Trucks ...................................................................................................................... 7 3.4. Designing for Bicycles .................................................................................................................. 10 3.5. Synthesis Summaries .................................................................................................................... 12 3.6. Guide Development ...................................................................................................................... 20 Conclusions and Suggested Research ................................................................................ 21 4.1. Conclusions .................................................................................................................................... 21 4.2. Suggested Research ...................................................................................................................... 21 References .............................................................................................................................. 25 Appendix A: Guide Bibliography .......................................................................................................... 27 Appendix B: Truck and Bicycle Research ............................................................................................. 39 Appendix C: Synthesis Summaries ....................................................................................................... 73 NCHRP Web-Only Document 347: Background and Summary of a Guide for Roundabouts is associated with NCHRP Research Report 1043: Guide for Roundabouts. Readers can read or purchase NCHRP Research Report 1043 on the National Academies Press website (nap.nationalacademies.org).