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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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2020 N A T I O N A L C O O P E R A T I V E H I G H W A Y R E S E A R C H P R O G R A M NCHRP RESEARCH REPORT 948 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges Kittelson & AssociAtes, inc. Wilmington, NC i n a s s o c i at i o n w i t h institute for trAnsportAtion reseArch And educAtion Raleigh, NC toole design group Silver Spring, MD Accessible design for the blind Asheville, NC Ats AmericAs Rockville, MD Subscriber Categories Design • Pedestrians and Bicyclists • Safety and Human Factors Research sponsored by the American Association of State Highway and Transportation Officials in cooperation with the Federal Highway Administration

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 transporta- tion results in increasingly complex problems of wide interest to high- way 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 ini- tiated 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 Agree- ment No. 693JJ31950003. The Transportation Research Board (TRB) of the National Academies of Sciences, Engineering, and Medicine was requested by AASHTO to administer the research program because of TRB’s recognized objectivity and understanding of modern research practices. TRB is uniquely suited for this purpose for many reasons: TRB maintains an extensive com- mittee structure from which authorities on any highway transportation subject may be drawn; TRB possesses avenues of communications and cooperation with federal, state, and local governmental agencies, univer- sities, and industry; TRB’s relationship to the National Academies is an insurance of objectivity; and TRB maintains a full-time staff of special- ists in highway transportation matters to bring the findings of research directly to those in a position to use them. The program is developed on the basis of research needs iden- tified by chief administrators and other staff of the highway and transportation departments, by committees of AASHTO, and by the FHWA. Topics of the highest merit are selected by the AASHTO Special Committee on Research and Innovation (R&I), and each year R&I’s recommendations are proposed to the AASHTO Board of Direc- tors and the National Academies. Research projects to address these top- ics are defined by NCHRP, and qualified research agencies are selected from submitted proposals. Administration and surveillance of research contracts are the responsibilities of the National Academies and TRB. The needs for highway research are many, and NCHRP can make significant contributions to solving highway transportation problems of mutual concern to many responsible groups. The program, however, is intended to complement, rather than to substitute for or duplicate, other highway research programs. Published research reports of the NATIONAL COOPERATIVE HIGHWAY 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.nationalacademies.org and then searching for TRB Printed in the United States of America NCHRP RESEARCH REPORT 948 Project 07-25 ISSN 2572-3766 (Print) ISSN 2572-3774 (Online) ISBN 978-0-309-67353-2 Library of Congress Control Number 2020947423 © 2020 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 Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; the FHWA; or the program sponsors. The Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; 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 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. The 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. The 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. The 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. The 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. The Transportation Research Board is one of seven major programs of the National Academies of Sciences, Engineering, and Medicine. The 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. The 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. 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. Learn more about the Transportation Research Board at www.TRB.org.

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 RESEARCH REPORT 948 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs William C. Rogers, Senior Program Officer Jarrel McAffee, Senior Program Assistant Eileen P. Delaney, Director of Publications Natalie Barnes, Associate Director of Publications NCHRP PROJECT 07-25 PANEL Field of Traffic—Area of Traffic Planning Brian J. Walsh, Washington State Department of Transportation, Olympia, WA (Chair) Stephen K. Bryan, Tennessee Department of Transportation, Nashville, TN Rachel A. Carpenter, California Department of Transportation, Sacramento, CA Joseph E. Hummer, North Carolina Department of Transportation, Raleigh, NC Mandar Khanal, Boise State University, Boise, ID Carissa Dale McQuiston, Michigan Department of Transportation, Lansing, MI Kenneth Mora, Texas Department of Transportation, Austin, TX Elise Ross, Connecticut Department of Transportation, Newington, CT Hua Xiang, Maryland Department of Transportation, Hanover, MD Brooke Struve, FHWA Liaison Bernardo B. Kleiner, TRB Liaison AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under NCHRP Project 07-25 by Kittelson & Associates, Inc.; Institute for Transportation Research and Education; Toole Design Group; Accessible Design for the Blind; and ATS Americas. Kittelson & Associates, Inc., was the contractor for this study. The work undertaken by other project team members occurred under subcontracts with Kittelson & Associates, Inc. Dr. Bastian Schroeder, P.E., Principal Engineer, Kittelson & Associates, Inc., was the principal investigator. Lee Rodegerdts, P.E., Principal Engineer, Kittelson & Associates, Inc., was project principal. The other authors of this report are Dr. Zachary Bugg, P.E., Senior Engineer, Kittelson & Associates, Inc.; Pete Jenior, P.E., P.T.O.E., Senior Engineer, Kittelson & Associates, Inc.; Shannon Warchol, P.E., Senior Engineer, Kittelson & Associates, Inc.; Mike Alston, Engineering Associate, Kittelson & Associates, Inc.; Dr. Ashley Haire, P.E., Project Engineer, Toole Design Group; Janet Barlow, C.O.M.S., Principal, Accessible Design for the Blind; and Gilbert Chlewicki, P.E., Director, ATS Americas. The project team acknowledges others who played significant roles in the project, including Jeremy Chrzan, P.E., P.T.O.E., Toole Design Group; Bill Schultheiss, P.E., Toole Design Group; Chris Cunningham, P.E., Institute for Transportation Research and Education; and Kyle Wurtz, Institute for Transportation Research and Education. The project team acknowledges the contributions of an invited panel of experts, including Brad Steckler, Indiana DOT; Steve King, Kansas DOT; Jody Colvin, Louisiana DOT; Cedric Ward, Maryland DOT; Andy Paul, Massachusetts DOT; Jim Rosenow, Minnesota DOT; Joshua Scott, Missouri DOT; Dirk Gross, Ohio DOT; Lori Lange, Tennessee DOT; Darren McDaniel, Texas DOT; and Joe Koscinski, Virginia DOT. Finally, the research team acknowledges the guidance, support, and inspiration provided by the NCHRP Project 07-25 Panel Chair and Panel Members throughout the course of the project and research efforts.

NCHRP Research Report 948: Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges provides specific guidance for four common Alternative Intersections and Interchanges (A.I.I.s): Diverging Diamond Interchange (DDI), Restricted Crossing U-Turn (RCUT), Median U-Turn (MUT), and Displaced Left-Turn (DLT). In addi- tion, the guide provides a principles-based approach that is applicable to any A.I.I. or conventional intersection form, including new A.I.I. forms not yet developed. A.I.I.s are designs that improve operations and safety for motorized traffic by strategically adjusting the geometric features at a given location, working on the general principle of redis- tributing motor vehicle demand at an intersection in an attempt to limit the need to add capacity with new lanes to improve traffic flow. These designs may involve reversing traffic lanes from their traditional directions, which may introduce confusion and create safety issues for pedestrians and bicyclists. In addition, pedestrian paths and bicycle facilities may cross through islands or take different routes than expected. These new designs are likely to require additional information for drivers, bicyclists, and pedestrians as well as better accommoda- tions for pedestrians and bicyclists, including pedestrians with disabilities. A central concern with A.I.I.s is how to provide information to pedestrians, bicyclists, and drivers about the direction of car traffic, pedestrian crossing, and bicycle facilities, par- ticularly when those new intersection designs feature unfamiliar traffic flows and patterns. The concern is acute for visually impaired pedestrians, who require information about the alignment of crosswalks, signal controls, crossing times, direction of traffic, and direction through islands. Under NCHRP Project 07-25, Guide for Pedestrian and Bicycle Safety at Alternative Inter- sections and Interchanges (A.I.I.), Kittelson & Associates was tasked with developing a guide to help transportation practitioners improve and integrate pedestrian and bicycle safety considerations at A.I.I.s through planning, design, and operational treatments. The guide (1) identifies and evaluates current practices, and emerging technologies and trends, in the United States and internationally; (2) describes current best practices for measuring the effectiveness of such A.I.I. treatments; (3) evaluates the safety and operational outcomes of specific A.I.I. treatments; and (4) identifies and ranks treatments for typical types of projects. F O R E W O R D By William C. Rogers Staff Officer Transportation Research Board

1-1 Chapter 1 Introduction 1-1 1.1 Objective and Scope of Guide 1-2 1.2 Overview of Alternative Intersections and Interchanges 1-6 1.3 Design and Evaluation Process 1-9 1.4 Organization of Guide 1-10 1.5 References 2-1 Chapter 2 Pedestrians 2-1 2.1 Characteristics of Pedestrians 2-7 2.2 Traversing 2-7 2.3 Wayfinding 2-10 2.4 Crossing 2-11 2.5 Design Principles for Pedestrian Facilities 2-14 2.6 References 3-1 Chapter 3 Bicycles 3-1 3.1 Characteristics of Bicyclists 3-3 3.2 Types of Bicycle Facilities 3-6 3.3 Selecting a Bikeway Type and Width 3-10 3.4 Design Principles for Bicycle Facilities 3-15 3.5 References 4-1 Chapter 4 Assessment 4-1 4.1 Facility Design Selection – ICE Stage 1 4-3 4.2 Quantitative Performance Measures – ICE Stages 1 and 2 4-7 4.3 Operational Analysis – ICE Stage 2 4-8 4.4 Design Flag Assessment 4-46 4.5 Design Flag Assessment Scoring Sheets 4-49 4.6 References 5-1 Chapter 5 Generalized Design Treatments 5-1 5.1 General Segment Treatments 5-4 5.2 General Intersection Treatments 5-12 5.3 General Crossing Treatments 5-19 5.4 Design Flag Treatments and Techniques 5-23 5.5 References 6-1 Chapter 6 Median U-Turn (MUT) Intersections 6-1 6.1 Introduction 6-2 6.2 Multimodal Operations 6-7 6.3 Safety and Comfort Characteristics 6-12 6.4 MUT Intersection-Level Concepts 6-18 6.5 Detailed Design Techniques 6-19 6.6 References C O N T E N T S

7-1 Chapter 7 Restricted Crossing U-Turn (RCUT) Intersections 7-1 7.1 Introduction 7-2 7.2 Multimodal Operations 7-6 7.3 Safety and Comfort 7-9 7.4 RCUT Intersection-Level Concepts 7-17 7.5 Detailed Design Techniques 7-23 7.6 References 8-1 Chapter 8 Displaced Left-Turn (DLT) Intersections 8-1 8.1 Introduction 8-1 8.2 Multimodal Operations 8-7 8.3 Safety and Comfort 8-13 8.4 DLT Intersection-Level Concepts 8-20 8.5 Detailed Design Techniques 8-25 8.6 References 9-1 Chapter 9 Diverging Diamond Interchanges (DDIs) 9-1 9.1 Introduction 9-1 9.2 Multimodal Operations 9-7 9.3 Safety and Comfort 9-13 9.4 DDI Level Concepts 9-20 9.5 Detailed Design Techniques 9-24 9.6 References

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Alternative Intersections and Interchanges (A.I.I.s) are designs that improve operations and safety for motorized traffic by strategically adjusting the geometric features at a given location, working on the general principle of redistributing motor vehicle demand at an intersection in an attempt to limit the need to add capacity with new lanes to improve traffic flow.

The TRB National Cooperative Highway Research Program's NCHRP Research Report 948: Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges provides specific guidance for four common A.I.I.s: Diverging Diamond Interchange (DDI), Restricted Crossing U-Turn (RCUT), Median U-Turn (MUT), and Displaced Left-Turn (DLT).

These designs may involve reversing traffic lanes from their traditional directions, which may introduce confusion and create safety issues for pedestrians and bicyclists. In addition, pedestrian paths and bicycle facilities may cross through islands or take different routes than expected. These new designs are likely to require additional information for drivers, bicyclists, and pedestrians as well as better accommodations for pedestrians and bicyclists, including pedestrians with disabilities.

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