Combined High-Visibility Enforcement: Determining the Effectiveness (2024)

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2024 BE H AVIORAL TRAFF IC SA FETY COOPERAT IVE RESEARCH PROGRA M BTSCRP RESEARCH REPORT 10 Research sponsored by the Governors Highway Safety Association and National Highway Trafc Safety Administration Subscriber Categories Pedestrians and Bicyclists • Operations and Trafc Management • Safety and Human Factors Combined High-Visibility Enforcement DETERMINING THE EFFECTIVENESS Shauna Hallmark Jonathan Wood Guillermo Basulto-Elias Zachary Hans eresa Litteral Nicole Oneyear Institute for Transportation Iowa State University Ames, IA Major Randy Kunert Law Enforcement Professional Des Moines, IA

BEHAVIORAL TRAFFIC SAFETY COOPERATIVE RESEARCH PROGRAM Since the widespread introduction of motor vehicles more than a century ago, crashes involving their operation remain a significant public health concern. While there have been enormous improvements in highway design and construction, as well as motor vehicle safety, which have been instrumental in lowering the rate of crashes per mil- lion miles in the United States, more than 35,000 people die every year in motor vehicle crashes. In far too many cases, the root causes of the crashes are the unsafe behaviors of motor vehicle operators, cyclists, and pedestrians. Understanding human behaviors and developing effective countermeasures to unsafe ones is difficult and remains a major weak- ness in our traffic safety efforts. The Behavioral Traffic Safety Cooperative Research Program (BTSCRP) develops practical solutions to save lives, prevent injuries, and reduce costs of road traffic crashes associated with unsafe behav- iors. BTSCRP is a forum for coordinated and collaborative research efforts. It is managed by the Transportation Research Board (TRB) under the direction and oversight of the Governors Highway Safety Association (GHSA) with funding provided by the National Highway Traffic Safety Administration (NHTSA). Funding for the program was originally established in Moving Ahead for Progress in the 21st Century (MAP-21), Subsection 402(c), which created the National Cooperative Research and Evaluation Program (NCREP). Fixing America’s Surface Transportation (FAST) Act continued the program. In 2017, GHSA entered into an agreement with TRB to manage the research activities, with the program name changed to Behavioral Traf- fic Safety Cooperative Research Program. The GHSA Executive Board serves as the governing board for the BTSCRP. The Board consists of officers, representatives of the 10 NHTSA regions, and committee and task force chairs. The Research Committee Chair appoints committee members who recommend projects for funding and provide oversight for the activities of BTSCRP. Its ultimate goal is to oversee a quality research program that is committed to addressing research issues facing State Highway Safety Offices. The Executive Board meets annually to approve research projects. Each selected project is assigned to a panel, appointed by TRB, which provides technical guidance and counsel throughout the life of the project. The majority of panel members rep- resent the intended users of the research projects and have an important role in helping to implement the results. BTSCRP produces a series of research reports and other products such as guidebooks for practitio- ners. Primary emphasis is placed on disseminating BTSCRP results to the intended users of the research: State Highway Safety Offices and their constituents. BTSCRP RESEARCH REPORT 10 Project BTS-17 ISSN 2766-5976 (Print) ISSN 2766-5984 (Online) ISBN 978-0-309-70954-5 Library of Congress Control Number 2024932853 © 2024 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 Transporta- tion Research Board; the National Academies of Sciences, Engineering, and Medicine; 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 Behavioral Traffic Safety Cooperative 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. Published research reports of the BEHAVIORAL TRAFFIC SAFETY COOPERATIVE 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

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AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under Behavioral Traffic Safety Cooperative Research Program (BTSCRP) Project BTS-17 by the Institute for Transportation (InTrans) at Iowa State University (ISU). ISU was the contractor for this study, with Major Randy Kunert (Ret.) serving as a subcontractor. The authors would like to acknowledge the many individuals and organizations that made this research project possible. The team would like to thank the Iowa Governor’s Traffic Safety Bureau (GTSB) for its assistance in obtaining data and providing recommendations and insights. 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 BTSCRP RESEARCH REPORT 10 Waseem Dekelbab, Deputy Director, Cooperative Research Programs Richard A. Retting, Senior Program Officer Dajaih Bias-Johnson, Senior Program Assistant Natalie Barnes, Director of Publications Heather DiAngelis, Associate Director of Publications Alison Shapiro, Editor BTSCRP PROJECT BTS-17 PANEL Grady T. Carrick, Enforcement Engineering, Inc., Ponte Vedra, FL Anthony DʹAgostino, New York State Sheriffs’ Association, Cohoes, NY Eric J. Fitzsimmons, Kansas State University, Manhattan, KS Winstina Hughes, Maryland State Highway Administration, Baltimore, MD Timothy Kerns, Maryland Department of Transportation, Glen Burnie, MD Jordan Blenner, NHTSA Liaison Bernardo B. Kleiner, TRB Liaison

BTSCRP Research Report 10 provides state highway safety offices (SHSOs) and other safety organizations with an improved understanding of safety outcomes associated with conducting combined high-visibility enforcement (HVE). The research team conducted a literature review along with a survey of current agency practices, developed an evaluation framework, and analyzed empirical data. This publication will be of interest to SHSOs, law enforcement agencies, and other stakeholders concerned with or considering the use of HVE to help reduce the prevalence of fatal and severe motor vehicle crashes. The National Highway Traffic Safety Administration (NHTSA) defines HVE as a universal traffic safety approach designed to create deterrence and change unlawful traffic behaviors. HVE combines highly visible and proactive law enforcement targeting a specific traffic safety issue. Law enforcement efforts are combined with visibility elements and a publicity strategy to educate the public and promote voluntary compliance with the law. SHSOs, in conjunction with state highway patrols and local law enforcement agencies, con- duct multiple HVE campaigns throughout the year as countermeasures to road user crashes caused by impaired driving, lack of seat belt use, distracted driving, and speeding. These annual campaigns are labor intensive for law enforcement agencies, and there are concerns about their effectiveness. NHTSA has funded several evaluations of combined enforcement programs with mixed results. In BTSCRP Project BTS-17, “Determining the Effectiveness of Combined High-Visibility Enforcement,” Iowa State University was asked to develop a scalable evaluation framework and methodologies to determine the effectiveness of HVE campaigns to reduce crash fre- quency and severity involving road user behaviors such as impaired driving, lack of seat belt use, distracted driving, and speeding. The research team (1) conducted a literature review; (2) conducted a survey of current agency practices; (3) developed and validated an evaluation framework and methodologies; (4) collected and analyzed empirical data; and (5) prepared final deliverables. Appendices A and B, an implementation plan, and recommendations for additional research are supplemental to this report and can be found on the National Academies Press website (nap.nationalacademies.org) by searching for BTSCRP Research Report 10: Combined High-Visibility Enforcement: Determining the Effectiveness. F O R E W O R D By Richard A. Retting Staff Officer Transportation Research Board

1 Summary 3 Chapter 1 Introduction 3 1.1 Background 3 1.2 Project Objectives 4 1.3 Operational Definitions 6 1.4 Overview of Report 8 Chapter 2 Description of HVE Campaigns and Effectiveness 8 2.1 Selection of Behaviors to Target in HVE Campaigns 9 2.2 Effectiveness of HVE Campaigns 19 2.3 Summary of Effectiveness of HVE 20 2.4 Common Methods to Evaluate HVE 22 Chapter 3 Survey of Agencies 28 Chapter 4 Description of Data Used for Evaluation of HVE 29 4.1 Description of Data Utilized in Analyses 31 4.2 Basic HVE Campaign Metrics 36 4.3 Crash Data 39 4.4 Statewide Citation/Violation Data 42 4.5 Speed Data 43 4.6 Seat Belt Use Data 44 4.7 Survey Data Utilized for Evaluation of Combined HVE 45 4.8 Exposure Data 46 4.9 Other Data Utilized 47 4.10 Resources 48 Chapter 5 Evaluation Frameworks 48 5.1 Description of Evaluation Frameworks 48 5.2 Outline of Analysis Framework Chapters 51 Chapter 6 Data Visualization Framework for Evaluation of HVE 51 6.1 Data Visualization Definition 51 6.2 Data Visualization Performance Metrics 51 6.3 Data Visualization Considerations 52 6.4 Steps to Create Data Visualizations 53 6.5 Data Visualization Strengths 53 6.6 Data Visualization Limitations 53 6.7 Technical and Computational Requirements for Data Visualization 54 6.8 Use of Dashboards to Interactively Visualize Data 55 6.9 Evaluation of the Data Visualization Framework to Assess the Impact of HVE and Combined HVE 66 6.10 Feasibility of Data Visualization for Evaluation of Combined HVE 70 6.11 Resources C O N T E N T S

71 Chapter 7 Simple Before-and-After Analysis 71 7.1 Simple Before-and-After Definition 72 7.2 Simple Before-and-After Analysis Performance Metrics 72 7.3 Common Types of Simple Before-and-After Analysis 76 7.4 Reporting Results 76 7.5 Simple Before-and-After Technical, Data, and Computational Requirements 76 7.6 Simple Before-and-After Strengths 77 7.7 Simple Before-and-After Limitations 77 7.8 Evaluation of Simple Before-and-After Statistical Framework to Assess the Impact of HVE and Combined HVE 89 7.9 Feasibility for Evaluation of Combined HVE Using Simple Before-and-After Statistics 90 Chapter 8 Classical Statistical Evaluations 90 8.1 Definition of Classical Statistics 92 8.2 Data Needs and Performance Metrics for Classical Statistics 93 8.3 Description of Analyses of Classical Statistics 93 8.4 Reporting Results for Classical Statistics 94 8.5 Strengths of Classical Statistics 95 8.6 Limitations of Classical Statistics 95 8.7 Evaluation of Classical Statistics Statistical Framework to Assess the Impact of HVE and Combined HVE 100 8.8 Feasibility for Evaluation of Combined HVE Using Classical Statistics 102 Chapter 9 Statistical Analysis with Spatial and/or Temporal Effects to Evaluate Impact of Combined HVE 102 9.1 Definition of Spatial and Temporal Statistical Analyses 102 9.2 Data Needs of Spatial and Temporal Statistical Analyses 104 9.3 Reporting Results for Spatial and Temporal Statistical Analyses 104 9.4 Strengths of Spatial and Temporal Statistical Analyses 105 9.5 Limitations of Spatial and Temporal Statistical Analyses 106 9.6 Evaluation of Spatial and Temporal Statistical Analyses Framework to Assess the Impact of HVE and Combined HVE 112 9.7 Feasibility for Evaluation of Combined HVE Using Temporal, Spatial, and Spatiotemporal Statistics 114 Chapter 10 Summary and Discussion 114 10.1 Project Summary 118 10.2 Proposals 122 References and Bibliography 126 Abbreviations, Acronyms, and Initialisms 127 Appendices A and B Note: Photographs, figures, and tables in this report may have been converted from color to grayscale for printing. The electronic version of the report (posted on the web at nap.nationalacademies.org) retains the color versions.