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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. 2015 www.TRB.org REPORT S2-S08D-RW-1 Analysis of Naturalistic Driving Study Data: Roadway Departures on Rural Two-Lane Curves Shauna L. haLLmark, nicoLe oneyear, Samantha tyner, and Bo Wang Center for Transportation Research and Education Institute for Transportation Iowa State University cher carney and dan mcgehee University of Iowa
Subject Areas Data and Information Technology Highways Operations and Traffic Management Safety and Human Factors Vehicles and Equipment
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. SHRP 2 Reports Available by subscription and through the TRB online bookstore: www.mytrb.org/store Contact the TRB Business Office: 202-334-3213 More information about SHRP 2: www.TRB.org/SHRP2 SHRP 2 Report S2-S08D-RW-1 ISBN: 978-0-309-27418-0 Â© 2015 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 prod- uct, 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 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 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. Victor J. Dzau 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
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 Kenneth L. Campbell, Chief Program Officer for SHRP 2 Safety, and James Hedlund, SHRP 2 Special Consultant for Safety Coordination. The authors thank the Virginia Tech Transportation Institute (VTTI) for providing the Naturalistic Driv- ing Study data and access to the secure data enclave, as well as for providing expertise and assistance in work- ing with the data. The authors also thank the Center for Transportation Research and Education (CTRE) at Iowa State University for providing the Roadway Information Database data. SHRP 2 STAFF Ann M. Brach, Director Stephen J. Andrle, Deputy Director Cynthia Allen, Editor Kenneth Campbell, Chief Program Officer, Safety Jared Cazel, Editorial Assistant JoAnn Coleman, Senior Program Assistant, Capacity and Reliability Eduardo Cusicanqui, Financial Officer Richard Deering, Special Consultant, Safety Data Phase 1 Planning Shantia Douglas, Senior Financial Assistant Charles Fay, Senior Program Officer, Safety Carol Ford, Senior Program Assistant, Renewal and Safety 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 Linda Mason, Communications Officer David Plazak, Senior Program Officer, Capacity and Reliability Rachel Taylor, Senior Editorial Assistant Dean Trackman, Managing Editor Connie Woldu, Administrative Coordinator
The SHRP 2 Naturalistic Driving Study (NDS) was the largest and most comprehensive study of its kind ever undertaken. Its central goal was to produce unparalleled data from which to study the role of driver performance and behavior in traffic safety and how driver behavior affects the risk of crashes. Such research involves understanding how a driver inter- acts with and adapts to the vehicle, the traffic environment, roadway characteristics, traffic control devices, and other environmental features. After-the-fact crash investigations can only provide this information indirectly. The NDS data recorded how drivers really drove and what they were doing just before they crashed or almost crashed. The Roadway Information Database (RID), created in parallel with the NDS, contains detailed roadway data collected on more than 12,500 centerline miles of highways in and around the six study sites, about 200,000 highway miles of data from the highway invento- ries of the six study states, and additional data on crash histories, traffic and weather condi- tions, work zones, and ongoing safety campaigns in the study sites. The NDS and RID data can be linked to associate driving behavior with the roadway environment. The data will be used for years to come for developing and evaluating safety countermeasures designed to prevent or reduce the severity of traffic crashes and injuries. The NDS collected data from more than 3,000 male and female volunteer passenger-vehicle drivers, aged 16 to 98, during a 3-year period. Most drivers participated from 1 to 2 years. It was conducted at one site in each of six states: Florida, Indiana, New York, North Carolina, Pennsylvania, and Washington. Data collected included vehicle speed, acceleration, and braking; vehicle controls, when available; lane position; forward radar; and video views forward, to the rear, and on the driverâs face and hands. The NDS data file contains about 50 million vehicle miles, 5 million trips, more than 3,900 vehicle years, and more than 1 million hours of videoâa total of about 2 petabytes of data. Four contracts were awarded in 2012 under SHRP 2 Safety Project S08, Analysis of the SHRP 2 Naturalistic Driving Study Data, to study specific research questions using the early NDS and RID data. An open competition solicited proposals to address topics of the con- tractorâs own choosing that would have direct safety applications and that would â¢ Lead to real-world applications and safety benefits (theoretical knowledge without poten- tial applications was not a priority); â¢ Be broadly applicable to a substantial number of drivers, roadways, or vehicles in the United States; and â¢ Demonstrate the use of the unique NDS data (i.e., similar results could not be obtained from existing nonnaturalistic data sets). In addition to these goals, SHRP 2 expected the projects to serve as both pilot testers and advisers. As they conducted these first substantial NDS and RID analyses, these studiesâ experienced researchers would discover valuable insights on a host of both pitfalls and opportunities that others should know about when they use the data. F O R EWO R D James Hedlund, SHRP 2 Special Consultant, Safety Coordination
The four projects began in February 2012 and were conducted in two phases. In Phase 1, which concluded in December 2012, contractors obtained an initial set of data, tested and refined their research plans, and developed detailed plans for their full analyses. Three projects successfully completed this proof of concept and were selected for Phase 2. These three projects obtained and analyzed a much richer, though still preliminary, data set and reported their results in July 2014. This report, Analysis of Naturalistic Driving Study Data: Roadway Departures on Rural Two-Lane Curves, documents one of the three projects. These projects were conducted while the NDS and RID data files were being built. This circumstance imposed constraints that substantially affected the researchersâ work. The constraints included the following: â¢ Sample size. In summer 2013, when the projects requested full data sets, the NDS data file was only 20% to 30% complete. As a result, each project could only obtain a fraction of the trips of interest now available in the full NDS data. â¢ RID not complete and not linked to the NDS. Projects based on roads of specific types or locations could not identify these roads from the RID but instead had to use Google Earth or a similar database to identify them. They then obtained trips of interest by using searches through the NDS that were less efficient than will be possible when the NDS and RID are linked. â¢ Data processing. Some data, such as radar, had not been processed from their raw state to a form where they were fully ready for analysis. â¢ Data quality. NDS data are field data, and field data are inherently somewhat messy. At the time these projects obtained their data, some data had not been quality controlled, and some characteristics of the data were not yet well understood. â¢ Tools for data users. Not all crashes and near crashes had been identified, and a separate small data set containing only crashes, near crashes, and baseline exposure segments had not been built. In addition, a small trip summary file containing key features of each trip had not been built. Users can conduct initial analyses on many subjects quickly and easily using a trip summary file. â¢ Other demands on data file managers. The first priority for the NDS manager, Virginia Tech Transportation Institute (VTTI), and the RID manager, Iowa State Universityâs Center for Transportation Research and Education (CTRE), was to complete data pro- cessing and quality control. Field data were being ingested continually. Data delivery for users was sometimes delayed because of these demands on their resources. These issues are being resolved in 2014. The NDS and RID data are complete and are being linked. Data processing and quality control are being completed. Crash and near- crash files and trip summary files are being built. If this project and the other two were to begin in 2015, each would have more data and would obtain the data far more easily and quickly. Readers should keep these constraints in mind as they read this report. Despite working under these constraints, the three NDS projects have produced valuable new insights into important traffic safety issues that will help reduce traffic crashes and injuries. For an overview of the study, see the following article: K. L. Campbell, The SHRP 2 Naturalistic Driving Study: Addressing Driver Performance and Behavior in Traffic Safety, TR News, No. 282, SeptemberâOctober 2012, pp. 30â35. Additional details may be found at the studyâs InSight website: https://insight.shrp2nds.us/.
C O N T E N T S 1 Executive Summary 1 Project Objectives 1 Research Questions Addressed 1 Data Collection and Reduction 2 Crash Surrogates 2 Results and Discussion 6 CHAPTER 1 SHRP 2 Naturalistic Driving Study Background 6 The First SHRP 2 NDS Analysis Projects 7 Constraints of the First SHRP 2 NDS Studies 8 CHAPTER 2 Introduction 8 Background 8 Rationale for Research 9 Objectives 9 Research Questions Addressed 10 CHAPTER 3 Data Collection 10 Identification of Data Needs 10 Data Requests 15 Summary of Data Received and Limitations 17 CHAPTER 4 Data Reduction 17 Reduction of Roadway Variables 17 Reduction of Vehicle, Traffic, and Environmental Variables 20 Reduction of Kinematic Driver Characteristics 22 Summary of Data Limitations 26 CHAPTER 5 Selection of Crash Surrogates 26 Identification of Possible Roadway Departure Crash Surrogates 27 Description of Selected Crash Surrogates 29 CHAPTER 6 Analysis for Research Question 1 29 Data Sampling and Variables Used for Research Question 1 30 Methodology for Defining Curve Area of Influence 31 Results for Research Question 1 35 Summary and Discussion 37 CHAPTER 7 Analysis for Research Question 2 37 Data Sampling and Segmentation Approach for Research Question 2 38 Variables Used for Research Question 2 38 Description of Analytical Approach for Research Question 2 40 Results for Research Question 2 42 Summary and Implications
44 CHAPTER 8 Analysis for Research Question 3 44 Data Sampling and Modeling Approach for Research Question 3 45 Variables Used for Research Question 3 46 Description of Analytical Approach and Results for Research Question 3 49 Summary of Crash/Near-Crash Events 49 Summary and Discussion 51 CHAPTER 9 Analysis for Research Question 4 51 Description of Analytical Approach for Research Question 4 51 Data Sampling and Segmentation Approach for Research Question 4 52 Variables Used for Research Question 4 52 Results for Research Question 4 54 Summary and Implications 56 CHAPTER 10 Summary and Recommendations 56 Summary 56 Discussion and Recommendations for Countermeasures 59 References 61 Appendix A. Methodology for Reducing Roadway Data 69 Appendix B. Data Reduction Method for Coding Driver Glance Location and Distraction 72 Appendix C. Curve Area of Influence Model Results