Estimating Effectiveness of Safety Treatments in the Absence of Crash Data (2023)

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NCHRP Web-Only Document 369 Estimating Effectiveness of Safety Treatments in the Absence of Crash Data R. J. Porter Juan Medina Michael Dunn University of Utah Kristin Kersavage Salt Lake City, UT Vikash Gayah Kim Eccles Bhagwant Persaud VHB Toronto, ON Raleigh, NC Conduct of Research Report for NCHRP Project 17-86 Submitted March 2023 © 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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COOPERATI VE RESEAR CH PROGRAMS CRP STAFF FOR NCHRP WEB-ONLY DOCUMENT 369 Waseem Dekelbab, Deputy Director, Cooperative Research Programs, and Manager, National Cooperative Highway Research Program David Jared, Senior Program Officer Mazen Alsharif, Senior Program Assistant Natalie Barnes, Director of Publications Heather DiAngelis, Associate Director of Publications Brendan Foht, Senior Editor Kathleen Mion, Assistant Editor NCHRP PROJECT 17-86 PANEL Field of Traffic—Area of Safety Bonnie S. Polin, Massachusetts Department of Transportation, Boston, MA (Chair) Paramvir S. Bhalia, Washington State Department of Transportation, Lacey, WA Kimberli R. Craft, Hoboken, NJ Matthew T. Enders, Washington State Department of Transportation, Olympia, WA Peter P. Hsu, Florida Department of Transportation, Tampa, FL Mohammad Jalayer, Rowan University, Glassboro, NJ Scott Neidert, Delaware Department of Transportation, Smyrna, DE Xiao Qin, University of Wisconsin, Milwaukee, Milwaukee, WI Shyam L. Sharma, Oregon Department of Transportation, Camas, WA Carol H. Tan, FHWA Liaison Kelly K. Hardy, AASHTO Liaison Bernardo B. Kleiner, TRB Liaison AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under NCHRP Project 17-86, “Estimating Effectiveness of Safety Treatments in the Absence of Crash Data.” This report was prepared by Dr. R. J. Porter, Mr. Michael Dunn, Dr. Kristin Kersavage, Dr. Vikash Gayah, and Ms. Kim Eccles of VHB; Dr. Juan Medina of the University of Utah; and Dr. Bhagwant Persaud, Consultant. Ms. Catherine Chestnutt, Ms. Annette Gross, and Ms. Angel Malaran of VHB played valuable roles in preparing the deliverables, including developing graphics and providing formatting and editorial reviews. Dr. Frank Gross of VHB served as an internal reviewer for the guide. Mr. Craig Lyon, formerly of Persaud & Lyon, contributed to initial drafts of the literature review and identification of safety treatments during Phase 1 of this research project. The authors wish to thank the City of Bellevue, Washington, the Utah Department of Transportation, and AMAG Technology for their assistance in providing data for the case studies. 

CONTENTS Chapter 1 Introduction ...................................................................................................................1 Overall Study Objectives ................................................................................................................. 3 Scope of Final Report ...................................................................................................................... 3 Chapter 2 Review of Literature ....................................................................................................4 Surrogate Measures Obtained from User-Level Trajectory Data .................................................... 4 Surrogates That Identify Potential Conflicts Between Users .......................................................... 5 Surrogates Obtained from User-Level Behavioral Measures ........................................................ 13 Surrogates Obtained from Macroscopic Traffic-Level Measures ................................................. 15 Other Methods ............................................................................................................................... 18 Surrogate Measures for Geometric Assessments........................................................................... 19 Crash Simulation ........................................................................................................................... 25 Collection of Surrogates from Field Data ...................................................................................... 26 Collection of Surrogates from Simulation ..................................................................................... 29 Linkages Between Surrogates and Crashes ................................................................................... 30 Conclusions.................................................................................................................................... 34 Chapter 3 Types of Data Collection Technologies for Surrogate Measurement ...................36 Video.............................................................................................................................................. 37 Vehicle Detectors........................................................................................................................... 42 Naturalistic Driving Studies ......................................................................................................... 46 Overview........................................................................................................................................ 46 Probe Vehicles ............................................................................................................................... 50 Overview........................................................................................................................................ 50 Microscopic Traffic Simulation ..................................................................................................... 54 Overview........................................................................................................................................ 54 Driving and Bicycling Simulators ................................................................................................. 59 Overview........................................................................................................................................ 59 Summary of Data Collection Methods .......................................................................................... 63 Chapter 4 Identify Safety Treatments with No or Low-Rated Crash Modification Factors..64 Identifying Safety Treatments with No or Low-Rated CMFs ....................................................... 64 Prioritization of Safety Treatments ................................................................................................ 70 Overall Ranking of Identified Treatments ..................................................................................... 73 Conclusion ..................................................................................................................................... 77 v 

Chapter 5 Case Studies ................................................................................................................82 Case Study 1: Evaluation of Leading Pedestrian Interval ............................................................ 82 Case Study 2: Evaluation of Traffic Signal Coordination ............................................................. 94 Chapter 6 Guide Development..................................................................................................111 Chapter 1: Introduction ................................................................................................................ 111 Chapter 2: Vision for Surrogate Use in Practice.......................................................................... 111 Chapter 3: Surrogate Measure Definitions .................................................................................. 112 Chapter 4: Types of Data Collection Technologies for Surrogate Measurement ........................ 113 Chapter 5: Study Design and Statistical Analysis Considerations .............................................. 113 Chapter 6: Types of Treatments for Evaluation with Surrogate Measures.................................. 113 Chapter 7: Case Studies ............................................................................................................... 114 Chapter 8: Summary and Recommendations for Future Work ................................................... 114 Chapter 9: References .................................................................................................................. 114 Chapter 7 Summary ...................................................................................................................115 Abbreviations .............................................................................................................................118 References ...................................................................................................................................120