Development of Crash Prediction Models for Short-Term Durations (2023)

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2023 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 1073 Development of Crash Prediction Models for Short-Term Durations Mohamed Abdel-Aty Naveen Eluru Nada Mahmoud Jingwan Fu Heesub Rim Tarek Hasan Abdulrahman Faden University of Central Florida Orlando, FL John N. Ivan Shanshan Zhao Kai Wang Manmohan Joshi University of Connecticut Storrs Mansfield, CT Subscriber Categories Operations and Trafc Management • Safety and Human Factors • Transportation, General Research sponsored by the American Association of State Highway and Transportation Ofcials 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 topics 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.mytrb.org/MyTRB/Store/default.aspx Printed in the United States of America NCHRP RESEARCH REPORT 1073 Project 22-48 ISSN 2572-3766 (Print) ISSN 2572-3774 (Online) ISBN 978-0-309-70917-0 Library of Congress Control Number 2023947125 © 2023 by the National Academy of Sciences. National Academies of Sciences, Engineering, and Medicine and the graphical logo are trade- marks of the 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, APTA, FAA, FHWA, FTA, GHSA, or NHTSA 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 does not develop, issue, or publish standards or spec- ifications. 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 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 or logos appear herein solely because they are considered essential to the object of the report.

e 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. e 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. e 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. e 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. e 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. e Transportation Research Board is one of seven major programs of the National Academies of Sciences, Engineering, and Medicine. e 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. e 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. e 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 1073 Waseem Dekelbab, Deputy Director, Cooperative Research Programs, and Manager, National Cooperative Highway Research Program Camille Crichton-Sumners, Senior Program Officer Mazen Alsharif, Senior Program Assistant Natalie Barnes, Director of Publications Heather DiAngelis, Associate Director of Publications Dominique Williams, Editor NCHRP PROJECT 22-48 PANEL Field of Design—Area of Vehicle Barrier Systems Kelly K. Campbell, Idaho Transportation Department, Boise, ID (Chair) Kevin T. Fitzgerald, Massachusetts Department of Transportation, Boston, MA Saleh R. Mousa, Booz Allen Hamilton, Austin, TX Anurag Pande, California Polytechnic State University, San Luis Obispo, CA Kendra Schenk, Burgess and Niple, Inc., Columbus, OH Shyuan-Ren (Clayton) Chen, FHWA Liaison Jerry Roche, FHWA Liaison Kelly K. Hardy, AASHTO Liaison

NCHRP Research Report 1073: Development of Crash Prediction Models for Short-Term Durations provides roadway safety practitioners within state departments of transportation with short-term crash prediction models to be used for estimating safety performance. The crash prediction tool, practitioners’ guide, training materials, and research report will be of immediate use toward improved crash prediction and the development of countermeasures. Crash prediction methods, which are used to identify crash hotspots or crash severity, consist of safety performance functions (SPFs), crash modification factors, and severity distribution functions. These tools use annual average daily traffic data along with geo- metric and operational characteristics to predict the annual average crash frequency. Crash prediction models have statistical value; however, they do little to predict crashes for variable, short-term periods, which is consistent with temporary work zones, special events, or time-of-day capacity changes. Road safety practitioners require the means to better assess daily and hourly changes or changes attributed to special conditions, such as the imple- mentation of active traffic management (ATM) strategies that could affect crash outcomes; help perform crash risk assessments; and provide effective countermeasures. Under NCHRP Project 22-48, “Development of Crash Prediction Models for Short- Term Durations,” the University of Central Florida used high-resolution traffic data to obtain detailed microscopic flow information to help fulfill the research objectives aimed to (1) develop short-term crash prediction models to estimate the safety performance of roadways; (2) identify explanatory variables measured over short durations; and (3) develop an implementation tool suitable for practitioner use. SPFs were developed for all main- line freeway segment types (i.e., basic, weaving, merge, diverge, and ramps) and different ATM scenarios, including high-occupancy vehicle lanes, variable speed limit/variable advisory speed limit, hard shoulder running, high-occupancy toll lanes, ramp metering, and work zones. NCHRP Research Report 1073: Development of Crash Prediction Models for Short-Term Durations and associated training materials will be of immediate use by roadway safety practitioners. A crash prediction tool and guide will be made available at https://www. highwaysafetymanual.org/Pages/Tools.aspx. The source code and data are posted on https:// github.com/NationalAcademies/NCHRP-22-48-Development-of-Crash-Prediction-Models -for-Short-Term-Durations. Training materials and a PowerPoint presentation are available on the National Academies Press website (nap.nationalacademies.org) by searching for NCHRP Research Report 1073: Development of Crash Prediction Models for Short-Term Durations. F O R E W O R D By Camille Crichton-Sumners Staff Officer Transportation Research Board

1 Summary 3 Chapter 1 Introduction 3 1.1 Project Background 4 1.2 Project Objectives 7 Chapter 2 Literature Review 7 2.1 Overview 9 2.2 Methodologies 19 2.3 Data Input and Variables 23 2.4 Summary 24 Chapter 3 Use Case Scenarios 24 3.1 Overview 24 3.2 Freeway Basic, Weaving, Merge, Diverge, and Ramp Segments 28 3.3 HSR 29 3.4 HOV Lanes 30 3.5 HOT Lanes 31 3.6 Reversible Lanes 32 3.7 Work Zones 33 3.8 Ramp Metering 34 3.9 VSL/VAS 36 Chapter 4 Collection, Integration, and Verification of the Usability of the Data 36 4.1 Data Collection 42 4.2 Data Processing, Integration, and Aggregation 46 4.3 Verifying the Usability of the Data 52 Chapter 5 Preliminary Model Comparison 53 5.1 Statistical Models 55 5.2 Machine-Learning Approaches 56 Chapter 6 Development of the Validated Crash Prediction Models for Short-Term Durations and Prioritized Use Case Scenarios 56 6.1 Overview 58 6.2 Development of Short-Term Crash Prediction Models 141 6.3 Evaluation of the Developed Models C O N T E N T S

147 Chapter 7 Calibration, Validation, and Transferability of the Developed Models 147 7.1 Short-Term Crash Prediction and Calibration Factor Calculations 160 7.2 Validation and Transferability of the Developed Freeway Basic Segment Models 164 7.3 Validation and Transferability of Use Case Scenarios 165 7.4 Case Study 175 Chapter 8 Web-Based Tool, User-Friendly Practitioners’ Guide, and Training Materials 178 Chapter 9 Summary and Conclusions 182 References 189 Appendix Summary of Previous Studies