Development of Analysis Methods Using Recent Data (2012)

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The Second S T R A T E G I C H I G H W A Y R E S E A R C H P R O G R A M TRANSPORTATION RESEARCH BOARD WASHINGTON, D.C. 2012 www.TRB.org REPORT S2-S01A-RW-1 Development of Analysis Methods Using Recent Data Gary Davis anD John hourDos University of Minnesota

Subscriber Categories Highways Safety and Human Factors

The Second Strategic Highway Research Program America’s highway system is critical to meeting the mobility and economic needs of local communities, regions, and the nation. Developments in research and technology—such as advanced materials, communications technology, new data collection tech- nologies, and human factors science—offer a new opportunity to improve the safety and reliability of this important national resource. Breakthrough resolution of significant transportation problems, however, requires concentrated resources over a short time frame. Reflecting this need, the second Strategic Highway Research Program (SHRP 2) has an intense, large-scale focus, integrates multiple fields of research and technology, and is fundamentally different from the broad, mission-oriented, discipline-based research programs that have been the mainstay of the highway research industry for half a century. The need for SHRP 2 was identified in TRB Special Report 260: Strategic Highway Research: Saving Lives, Reducing Congestion, Improving Quality of Life, published in 2001 and based on a study sponsored by Congress through the Transportation Equity Act for the 21st Century (TEA-21). SHRP 2, modeled after the first Strategic Highway Research Program, is a focused, time- constrained, management-driven program designed to comple- ment existing highway research programs. SHRP 2 focuses on applied research in four areas: Safety, to prevent or reduce the severity of highway crashes by understanding driver behavior; Renewal, to address the aging infrastructure through rapid design and construction methods that cause minimal disrup- tions and produce lasting facilities; Reliability, to reduce con- gestion through incident reduction, management, response, and mitigation; and Capacity, to integrate mobility, economic, envi- ronmental, and community needs in the planning and designing of new transportation capacity. SHRP 2 was authorized in August 2005 as part of the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU). The program is managed by the Transportation Research Board (TRB) on behalf of the National Research Council (NRC). SHRP 2 is conducted under a memorandum of understanding among the American Associa- tion of State Highway and Transportation Officials (AASHTO), the Federal Highway Administration (FHWA), and the National Academy of Sciences, parent organization of TRB and NRC. The program provides for competitive, merit-based selection of research contractors; independent research project oversight; and dissemination of research results. SHRP 2 Report S2-S01A-RW-1 ISBN: 978-0-309-12889-6 © 2012 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 copy- right to any previously published or copyrighted material used herein. The second Strategic Highway Research Program grants permission to repro- duce material in this publication for classroom and not-for-profit purposes. Per- mission is given with the understanding that none of the material will be used to imply TRB, AASHTO, or FHWA endorsement of a particular product, method, or practice. It is expected that those reproducing material in this document for educational and not-for-profit purposes will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from SHRP 2. Note: SHRP 2 report numbers convey the program, focus area, project number, and publication format. Report numbers ending in “w” are published as web documents only. Notice The project that is the subject of this report was a part of the second Strategic Highway Research Program, conducted by the Transportation Research Board with the approval of the Governing Board of the National Research Council. The members of the technical committee selected to monitor this project and to review this report were chosen for their special competencies and with regard for appropriate balance. The report was reviewed by the technical committee and accepted for publication according to procedures established and overseen by the Transportation Research Board and approved by the Governing Board of the National Research Council. 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 Research Council, or the program sponsors. The Transportation Research Board of the National Academies, the National Research Council, and the sponsors of the second Strategic 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. SHRP 2 Reports Available by subscription and through the TRB online bookstore: www.TRB.org/bookstore Contact the TRB Business Office: 202-334-3213 More information about SHRP 2: www.TRB.org/SHRP2

The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. On the authority of the charter granted to it by Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Ralph J. Cicerone is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achieve- ments of engineers. Dr. Charles M. Vest is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, on its own initiative, to identify issues of medical care, research, and education. Dr. Harvey V. Fineberg is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy’s purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Ralph J. Cicerone and Dr. Charles M. Vest are chair and vice chair, respectively, of the National Research Council. The Transportation Research Board is one of six major divisions of the National Research Council. The mission of the Transportation Research Board is to provide leadership in transportation innovation and progress through research and information exchange, conducted within a setting that is objective, interdisci- plinary, and multimodal. The Board’s varied activities annually engage about 7,000 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 Transporta- tion, and other organizations and individuals interested in the development of transportation. www.TRB.org www.national-academies.org

SHRP 2 Staff Ann M. Brach, Director Stephen Andrle, Deputy Director Kizzy Anderson, Senior Program Assistant, Implementation James Bryant, Senior Program Officer, Renewal Mark Bush, Senior Program Officer, Renewal Kenneth Campbell, Chief Program Officer, Safety JoAnn Coleman, Senior Program Assistant, Capacity Eduardo Cusicanqui, Finance Officer Walter Diewald, Senior Program Officer, Safety Jerry DiMaggio, Implementation Coordinator Charles Fay, Senior Program Officer, Safety Carol Ford, Senior Program Assistant, Safety Elizabeth Forney, Assistant Editor Jo Allen Gause, Senior Program Officer, Capacity Abdelmename Hedhli, Visiting Professional James Hedlund, Special Consultant, Safety Coordination Ralph Hessian, Visiting Professional Andy Horosko, Special Consultant, Safety Field Data Collection William Hyman, Senior Program Officer, Reliability Linda Mason, Communications Officer Michael Miller, Senior Program Assistant, Reliability Gummada Murthy, Senior Program Officer, Reliability David Plazak, Senior Program Officer, Capacity Monica Starnes, Senior Program Officer, Renewal Noreen Stevenson-Fenwick, Senior Program Assistant, Renewal Charles Taylor, Special Consultant, Renewal Onno Tool, Visiting Professional Dean Trackman, Managing Editor Pat Williams, Administrative Assistant Connie Woldu, Administrative Coordinator Patrick Zelinski, Communications Specialist acknowledgmentS This work was sponsored by the Federal Highway Administration in cooperation with the American Asso- ciation of State Highway and Transportation Officials. It was conducted in the second Strategic Highway Research Program (SHRP 2), which is administered by the Transportation Research Board of the National Academies. The project was managed by Walter Diewald, Senior Program Officer for SHRP 2 Safety. The research described in this report was performed under SHRP 2 Safety Project S01A by the Center for Transportation Studies, the Minnesota Traffic Observatory, and the Department of Civil Engineering of the University of Minnesota. Gary A. Davis, Professor of Civil Engineering, was the principal investigator. Other authors of this report are John Hourdos, Director of the Minnesota Traffic Observatory and co-principal investigator; Ted Morris, Manager of the Minnesota Traffic Observatory; and Hui Xiong and Indrajit Chatterjee, Graduate Assistants in the Department of Civil Engineering.

F o r e w o r d Walter Diewald, PhD, SHRP 2 Senior Program Officer, Safety A large component of the safety research undertaken in the second Strategic Highway Research Program (SHRP 2) is aimed at reducing injuries and fatalities that result from high- way crashes. Through a naturalistic driving study (NDS) involving more than 3,000 volunteer drivers, SHRP 2 expects to learn more about how individual driver behavior interacts with vehicle and roadway characteristics. In anticipation of the large volume of data to be col- lected during the SHRP 2 NDS, several projects were undertaken to demonstrate that it is possible to use existing NDS data and data from other sources to further the understanding of the risk factors associated with road crashes. More specifically, the four projects conducted under the title Development of Analysis Methods Using Recent Data examined the statistical relationship between surrogate measures of collisions (conflicts, critical incidents, near col- lisions, or roadside encroachment) and actual collisions. This report presents the results of one of these projects, undertaken by the Center for Transportation Studies at the University of Minnesota. This report documents the second phase of a two-phase project under SHRP 2 Safety Project S01A. The primary objective of this work was to establish an analytic foundation for using conflicts and near crashes as surrogate measures. The project introduced a counterfactual analytic approach suggesting that a traffic event qualifies as a crash cause under two con- ditions: (a) both the event and the crash occurred and (b) had the event in question not occurred, then the crash also would not have occurred. Data from site-based field studies and vehicle studies were used to extend these ideas from a trajectory model to more complicated scenarios. The report introduces an approach to microscopic (i.e., individual event) modeling of crash- related events, where driver actions, initial speeds, and vehicle locations are treated as inputs to a physical model describing vehicle motion. This choice of modeling strategy reflects a need for such models if realistic crash processes are to be included in microscopic traffic simulation models. The simple trajectory model can be used to estimate features of crash and near-crash events—such as driver reaction times, following headways, and deceleration rates—from trajectory data produced from a site-based field study. Given sufficiently large samples of crash and near-crash events, this method can be used to compile distributions for these inputs for use in traffic simulation models. Finally, the report illustrates how a trajectory model, together with estimates of input variables, can quantify the degree to which a non-crash event could have been a crash event. The report describes how these ideas were extended to more complicated scenarios by using data from both vehicle- and site-based field studies, including data obtained from the 100-car vehicle-based field study, data from site-based video on Interstate 94 from the Minnesota Traffic Observatory, and site-based radar data from the Cooperative Intersection Collision Avoidance Systems (CICAS) intersection in North Carolina.

C o n t e n t s 1 Executive Summary 4 cHaPteR 1 Background and Project Objectives 4 Background 4 Highway Safety Manual 5 SHRP 2 Safety Program 5 Structural Modeling of Crash-Related Events 6 Crash Surrogates 8 Summary 9 References 10 cHaPteR 2 Overview of Analytic Method 10 State-Space Model 11 Illustrative Example 15 References 16 cHaPteR 3 Analyses Using Vehicle-Based Data 16 Data Acquisition and Preparation 16 Case 99540 21 Case 104119 22 Case 73082 25 Case 104851 26 Case 104283 28 Case 60289 28 Case 92660 40 cHaPteR 4 Analyses Using Site-Based Video Data 40 Data Acquisition and Preparation 40 I-94 Case 1 40 I-94 Case 2 44 I-94 Case 3 46 I-94 Case 4 53 cHaPteR 5 Analyses Using CICAS Site-Based System 53 General Methodology 55 CICAS North Carolina US-74E Near-Crash Case: 12:11 p.m., April 25, 2007 64 cHaPteR 6 Conclusions and Recommendations 64 Summary 64 Conclusions 66 Recommendations for Future Work 66 Reference 67 Appendix A. Analysis Tools Developed in This Project 71 Appendix B. The CICAS Site-Based System 78 Appendix C. Outline of a Causal Theory of Traffic Conflicts and Collisions