Microscopic Overtaking Model to Simulate Two-lane Highway Traffic Operation and Safety Performance by Amir Hosein Ghods A thesis presented to the University of Waterloo in fulfillment of the thesis requirement for the degree of Doctor of Philosophy in Civil Engineering Waterloo, Ontario, Canada, 2013 ©Amir Hosein Ghods 2013 AUTHOR'S DECLARATION I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. I understand that my thesis may be made electronically available to the public. ii Abstract Rural two-lane highways make up a large portion of road networks around the world. The special geometric and traffic attributes of these highways pose special challenges to safety and traffic operation. In recent years, microscopic simulation models have gained increased acceptance as a reliable tool for investigating traffic operations and evaluating safety performance. Despite this trend, the development and application of these models to two-lane highway operations has not kept pace with those of freeways and urban networks, and this is due, in large part, to difficulties in modeling the overtaking process. This process has been rendered complex by the large number of inter-related decision factors that need to be considered by the overtaking driver in a bi-directional driving regime. In this research, a new overtaking gap-acceptance model is developed to simulate traffic operation and safety performance on two-lane highways. This model considers a wide spectrum of physical and behavioral variables that could affect overtaking. It does so by introducing a new safety-based gap- acceptance decision variable based on the overtaking driver’s perception of time-to-collision (TTC) with an opposing vehicle. The decision to overtake was expressed as a function of the perceived TTC in comparison to an established driver risk threshold (critical TTC). The distribution of critical TTC among drivers are determined through a model calibration and validation procedure based on overtaking observational data obtained from a video-recording of a one-kilometer segment of a two- lane highway. Unlike previous models, the proposed gap-acceptance model makes use of only a few calibration parameters. The proposed overtaking models along with other components of a micro- simulation traffic model are implemented in a software framework that can simulate traffic and safety operation for two-lane highways. The overall simulation results demonstrate that the proposed simulation model can provide reliable measures of traffic and safety for two-lane highway operation. The overtaking model was found to yield both consistent and transferable results. The model is then applied successfully to provide more accurate estimates of traffic measures used in level-of-service analysis for two-lane highways and to compare these results to values reported in the two versions of the Highway Capacity Manual (HCM). In another application, this model is used to investigate the impact of truck mandated speed limiters on safety and traffic operation of two-lane highways and specifically their impact on overtaking. Finally, the potential implications of adaptive cruise control for overtaking and its resultant traffic and safety impacts are studied using the developed simulation model. iii Acknowledgements I express sincere gratitude to my supervisor, Professor Frank Saccomanno, for this research opportunity and his continuous support and guidance during my study. Without his guidance and useful advices this dissertation would not have been possible. I thank my committee members, Professor Liping Fu, Professor Bruce Hellinga, Professor Carl Haas, Professor Ralph Haas, and Professor Jonathan Histon for their time, support and helpful advices and comments. I am also very grateful to my external examiner, Professor Laurence Rilett, for his invaluable time for evaluating my thesis and his helpful comments. I thank my colleagues Dr. Piero Guido and Giofrè Vincenzo Pasquale at the University of Calabria, Italy for their help in data collection and development of data analysis software for this research. I sincerely thank my good friends and colleagues at the University of Waterloo Ehsan Bagheri, Shahin Karimi, Soroush Salek Moghadam, Reza Noroozi, Shahram Hashemi Vaziri, Akram Nour, Pedram Izadpanah, Usama Shahdah, David Duong, Ramona Mirtorabi, Roshanak Taghipour, and Tae J. Kwon for their help and creating memorable time during the years of my PhD study. I would like to thank my parents Mohammad Ghods and Parvaneh Shariatpanahi for their unconditional love, support, and motivation to continue my study to higher levels. I am grateful to my older brother Pouria Ghods for his continuing guidance and support and my younger brother Amir Reza Ghods for his help. Finally and most importantly, I would like to thank my wife Fatemeh for her love, support, encouragement, and patience. My PhD research would have been never possible without her. My warmest thanks and love goes to her for being beside me all the time and for helping me to overcome the study and life difficulties. iv Dedication This thesis is dedicated To my beloved wife, Fatemeh And To my adoring parents. v Table of Contents AUTHOR'S DECLARATION ............................................................................................................... ii Abstract ................................................................................................................................................. iii Acknowledgements ............................................................................................................................... iv Dedication .............................................................................................................................................. v Table of Contents .................................................................................................................................. vi List of Figures ....................................................................................................................................... ix List of Tables ........................................................................................................................................ xii Chapter 1 Introduction ............................................................................................................................ 1 1.1 Background .................................................................................................................................. 1 1.2 Problem Statement........................................................................................................................ 2 1.3 Objectives ..................................................................................................................................... 4 1.4 Thesis Outline ............................................................................................................................... 5 Chapter 2 Two-lane Traffic Simulation Framework .............................................................................. 6 2.1 Introduction .................................................................................................................................. 6 2.2 Model Structure ............................................................................................................................ 6 2.3 Traffic Flow .................................................................................................................................. 8 2.3.1 Platoon generation model ...................................................................................................... 8 2.3.2 Headway generation model ................................................................................................. 12 2.3.3 Proportion of vehicle types .................................................................................................. 13 2.4 Vehicle Characteristics and Performance ................................................................................... 13 2.5 Desired Speed ............................................................................................................................. 17 2.6 Road Data ................................................................................................................................... 18 2.7 Driving Regimes ......................................................................................................................... 19 2.7.1 Free-flow ............................................................................................................................. 20 2.7.2 Car-following ...................................................................................................................... 21 2.7.3 Overtaking ........................................................................................................................... 22 2.8 Simulation Platform.................................................................................................................... 27 2.9 Conclusion .................................................................................................................................. 30 Chapter 3 Overtaking Gap-acceptance Model...................................................................................... 32 3.1 Introduction ...............................................................................................................................