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TRANSPORTATION RESEARCH BOARD WASHINGTON, D.C. 2013 www.TRB.org RepoRt S2-S01C-RW-1 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 A Multivariate Analysis of Crash and Naturalistic Driving Data in Relation to Highway Factors T. J. Gordon, L. P. KosTyniuK, P. E. GrEEn, M. A. BArnEs, d. F. BLowEr, s. E. BoGArd, A. d. BLAnKEsPoor, And d. J. LEBLAnc University of Michigan Transportation Research Institute B. r. cAnnon And s. B. McLAuGhLin Virginia Tech Transportation Institute
Subscriber Categories Highways Safety and Human Factors
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 SHRP 2 Report S2-S01C-RW-1 ISBN: 978-0-309-12890-2 © 2013 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. Permission 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 âwâ 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 manufacturersâ names appear herein solely because they are considered essential to the object of the report. The Second Strategic Highway Research Program Americaâs highway system is critical to meeting the mobility and economic needs of local communities, regions, and the nation. Developments in research and technologyâsuch as advanced materials, communications technology, new data collection tech- nologies, and human factors scienceâoffer 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 com- plement 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 disruptions and produce lasting facilities; Reliability, to reduce congestion through incident reduction, management, response, and mitigation; and Capacity, to integrate mobility, economic, environmental, and community needs in the planning and designing of new trans- portation 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 memo- randum of understanding among the American Association 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.
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. C. D. (Dan) Mote, Jr., 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 Academyâs 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. C. D. (Dan) Mote, Jr., 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 Boardâs 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 J. Andrle, Deputy Director Neil J. Pedersen, Deputy Director, Implementation and Communications James Bryant, Senior Program Officer, Renewal Kenneth Campbell, Chief Program Officer, Safety JoAnn Coleman, Senior Program Assistant, Capacity and Reliability Eduardo Cusicanqui, Financial Officer Walter Diewald, Senior Program Officer, Safety Jerry DiMaggio, Implementation Coordinator Shantia Douglas, Senior Financial Assistant Charles Fay, Senior Program Officer, Safety Carol Ford, Senior Program Assistant, Renewal and Safety Elizabeth Forney, Assistant Editor Jo Allen Gause, Senior Program Officer, Capacity Rosalind Gomes, Accounting/Financial Assistant Abdelmename Hedhli, Visiting Professional James Hedlund, Special Consultant, Safety Coordination Alyssa Hernandez, Reports Coordinator Ralph Hessian, Special Consultant, Capacity and Reliability Andy Horosko, Special Consultant, Safety Field Data Collection William Hyman, Senior Program Officer, Reliability Michael Marazzi, Senior Editorial Assistant Linda Mason, Communications Officer Reena Mathews, Senior Program Officer, Capacity and Reliability Matthew Miller, Program Officer, Capacity and Reliability Michael Miller, Senior Program Assistant, Capacity and Reliability David Plazak, Senior Program Officer, Capacity Onno Tool, Visiting Professional Dean Trackman, Managing Editor Connie Woldu, Administrative Coordinator Patrick Zelinski, Communications/Media Associate 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 Safety. The research reported herein was performed by the University of Michigan Transportation Research Institute (UMTRI) in collaboration with the Virginia Tech Transportation Institute (VTTI). Timothy Gordon was the project director and principal investigator. The authors acknowledge the important role of Michael Hagan and other members of the UMTRI Engineering Research Division, who collected and managed the naturalistic driving data used in this project. Additional thanks are due to the Michigan Department of Transportation for providing the Highway Performance Management System data for the public road system and to the Michigan Center for Geographic Information for providing the digital public road framework map.
A large component of the safety research undertaken in the second Strategic Highway Research Program (SHRP 2) is aimed at reducing the injuries and fatalities that result from highway crashes. Through a naturalistic driving study (NDS) involving more than 3,000 vol- unteer 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 collected during the NDS, several projects were conducted to demonstrate that it is possible to use existing data from previous naturalistic driving studies and data from other sources to further the understanding of the risk factors associated with road crashes. More spe- cifically, the four S01 projects, titled Development of Analysis Methods Using Recent Data, examined the statistical relationship between surrogate measures of collisions (conflicts, critical incidents, near collisions, and roadside encroachment) and actual collisions. This report presents the results of one of these projects, undertaken by the University of Michigan Transportation Research Institute. This report documents the second phase of a two-phase project under SHRP 2 Safety Project S01C. A primary part of this work involved conducting a multivariate analysis of crash and naturalistic driving data in relation to highway factors. A geographic information system (GIS) framework was used as the basis for fusing multiple information sources to analyze road departure crash risk. A major goal was to use this method to support formulation and validation of crash surrogates. Two analytical models developed in the study focus on the statistical relationship between surrogate measures of crashes and actual crashes and on the formulation of exposure-based risk measures using surrogate measures. The first approach is an extension of the traditional univariate response model for crashes to a model that treats crashes and crash surrogates as a bivariate response variable, incorporates a correlation structure between them, and can be extended to a Bayesian model. The second approach is based on extreme value theory and estimates the probability of events that are more extreme than any that have been observed. The surrogate measures examined ranged from relatively simple measures based on lane position and time to the crossing of a lane boundary to more complex measures, such as a driverâs adjustment of the vehicle yaw angle to match that of the road. The report also describes three exploratory studies that illustrate the value of the geo- spatial approach taken. The first study examined the application of spatial statistics to the problem of determining if concentrations of crashes were really âhot spotsâ or if they could be considered simply random groupings. The second study compared surrogate event rates in episodes of driving while on and off using a cell phone. The comparison was made for the same driver for the same conditions. The third study compared the yaw rate error of drivers through areas of lane widening and locations with uniform lane widths. The results of each exploratory study suggest that the combination of naturalistic, crash, and highway data provides a rich data resource for many types of research. F O R EWO R D Walter Diewald, PhD, SHRP 2 Senior Program Officer, Safety
This report provides valuable background information to highway safety analysts seek- ing to use the data that will be made available from the SHRP 2 NDS. The beneficiaries of such research will be the nationâs highway users as vehicle design and road design, as well as highway traffic control, are improved through the analytical use of the data.
C O n t E n t s 1 Executive Summary 3 CHAPTER 1 Introduction 5 CHAPTER 2 Research Questions 5 Research Hypotheses 6 Broad Research Questions 6 Specific Safety Research Questions 7 Data Quality and Validation 8 CHAPTER 3 Data Sources 8 UMTRI Naturalistic Driving Data 8 Highway Data 9 Crash Data 10 Analysis Data 12 CHAPTER 4 Surrogates for Road Departure Crashes 12 Overview of Available Surrogates 14 Specific Surrogates Used for Analysis 16 CHAPTER 5 Statistical Analysis: A Unified Approach to the Analysis of Rates for Crashes and Crash Surrogates 16 Traditional Analysis of Crash Data 16 Seemingly Unrelated Regression Model 18 Poisson Log-Linear Models Estimated by Weighted Least Squares 18 Bayesian SUR for Log-Linear Models 19 SUR Model Application and Results 24 CHAPTER 6 Statistical Analysis: An Approach Using Extreme Value Theory 24 Extreme Value Analysis 27 CHAPTER 7 Yaw Rate Error 35 CHAPTER 8 Orthogonal Studies 35 Road Departure Crash Spatial Analysis 36 Cell Phone Use 37 Road Boundary Change and Yaw Rate Error 40 CHAPTER 9 Transferability to Other Data Sources 40 Data Used for Testing 41 Method 42 NDD through VDOT Hot Spots 46 Summary
48 CHAPTER 10 Conclusions 51 References 54 Appendix A. Literature Review: Crash Rates and Highway, Environmental, and Driver Factors 59 Appendix B. Road Departure Crashes by Environmental and Driver Conditions 61 Appendix C. Data Tables 63 Appendix D. Determination of Yaw Rate Error from Vehicle-Based Measurements
