Individual and Environmental Determinants of Traffic Emissions and Near-Road Air Quality

Individual and Environmental Determinants of Traffic Emissions and Near-Road Air Quality by Junshi Xu A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Department of Civil Engineering University of Toronto © Copyright by Junshi Xu 2020 Individual and environmental determinants of traffic emissions and near-road air quality Junshi Xu Doctor of Philosophy Department of Civil Engineering University of Toronto 2020 Abstract On-road motor vehicles are responsible for a considerable proportion of near-road air pollution. While background levels of air pollutants are continuously tracked by regional monitoring networks, assessing near-road air quality remains a challenge in urban areas with complex built environments, traffic composition, and meteorological variation, leading to significant spatiotemporal variability in air pollution. This research addresses current gaps in the literature on local traffic emissions and near-road air quality. This thesis first investigates the effect of traffic volume and speed data on the simulation of vehicle emissions and hotspot analysis. Traffic emissions are estimated using radar data as well as simulated traffic based on various speed aggregation methods. It provides recommendations for project-level analysis and particulate matter (PM) hotspot analysis. We further compare fleet averaged emission factors (EFs) derived from a traffic emission model, the Motor Vehicle Emissions Simulator (MOVES), with EFs using plume-based measurements. This second module stresses the need to collect local traffic information for a better understanding of on-road traffic emissions. Besides, we validate default drive cycles in MOVES against representative drive cycles derived based on real-world GPS data. The validation results ii are helpful for transportation planners to quantify uncertainties in emission estimation and employ appropriate methods to improve the estimation of on-road emission inventories. The third module develops eco-score models and evaluates the effect of various factors such as driver and trip characteristics on emission intensities. The results shed light on the impact of driving style on emissions and identify the most important factors affecting the amount of emissions generated by every individual driver. The fourth module focuses on the impact of traffic emissions on near-road air quality and presents the results of two different experiments. First, it explores the effect of various factors on near-road ultrafine particle (UFP) concentrations based on short-term fixed monitoring, which stresses the significance of using local traffic characteristics to improve near-road air quality prediction. In addition, it captures the distribution of truck movements in urban environments and investigates the impacts of land-use variables and detailed traffic information on near-road Black Carbon (BC) concentrations. iii Acknowledgments First of all, I would like to express my deepest and sincere gratitude to my supervisor, Professor Marianne Hatzopoulou, for her tremendous support, inspiring guidance, and motivational mentorship which has encouraged me to grow as a researcher throughout my studies at the University of Toronto. I have been so lucky to have you as a mentor since my Master’s degree. Your mentorship has been an invaluable gift over the past years. One day, I hope to inspire someone else as you've inspired me. Thank you for being such a great role model. I would like to further express my appreciation to my Ph.D. supervisory committee members, Professor Matthew Roorda, Professor Amer Shalaby, and Professor Heather MacLean, for providing me with their great support and invaluable advice. I would also like to thank my external examiner Professor Guohua Song, for his thoughtful comments and suggestions. My experience would not have been the same without the friends I met throughout my studies. I would like to thank Soheil Alizadeh, Sina Bahrami, Md Sami Hasnine, Ahmadreza Faghih Imani, Ehab Diab, Albert Lo, Dengbo He, and Ariel Hu for their support and friendship. I have been extremely fortunate to work with incredibly talented friends and colleagues in the Transportation and Air Quality Research Group (TRAQ) for making my Ph.D. adventure at UofT such an incredible and unforgettable experience: An Wang, Ran Tu, Laura Minet, Christos Stogios, Marc Saleh, Jessie Gai, Arman Ganji, Maryam Sherkarrizfard, Ahsan Alam, and Sabreena Anowar. Thank you for all your support and help over the years. Thank you for providing invaluable feedback and helping with data collection. I am truly indebted to the Mitacs organization for its confidence in my ability and awarding me the Globalink Graduate Fellowship throughout my graduate studies. I am forever grateful to my parents, Lilan Tao and Fangqing Xu, for their unwavering support in all my endeavours. I thank them both for their unconditional support and for all the sacrifices they have made for me throughout all those years. Lastly, special thanks to Mingqian Zhang for her endless love and support, who is more than a girlfriend, she is a lifelong partner. Thank you for being by my side through this whole adventure every step of the way. You are a constant source of joy and happiness and never stop believing in me. I cannot imagine this journey without you in my life. iv Table of Contents Acknowledgments ........................................................................................................................ iv Table of Contents .......................................................................................................................... v List of Tables ................................................................................................................................. x List of Figures ............................................................................................................................... xi List of Abbreviations .................................................................................................................. xv Author Contributions ............................................................................................................... xvii Publication Details ..................................................................................................................... xix Chapter 1 Introduction and Objectives ...................................................................................... 1 Chapter overview .................................................................................................................. 1 1.1 Background and motivation ......................................................................................................1 1.2 Problem statement .....................................................................................................................3 1.3 Research questions .....................................................................................................................5 1.4 Research significance .................................................................................................................6 1.5 Dissertation structure and overview of chapters .....................................................................7 1.6 Note on the use of units in this document ................................................................................9 Chapter 2 Context around Traffic Emissions and Near-Road Air Quality Modelling ........ 10 Chapter overview ................................................................................................................ 10 2.1 Existing efforts in validating traffic emission models ...........................................................10 2.1.1 Traffic emission model validation based on emission factors ............................................................. 11 2.1.2 Traffic emission model validation based on vehicle dynamics ........................................................... 15 2.2 Refining near-road air quality models ...................................................................................17 2.2.1 Evolutions in data sources and collection methods ............................................................................. 17 2.2.2 Improvements in air quality modelling ................................................................................................ 22 2.3 Identified gaps in the current literature .................................................................................26 Chapter 3 Contrasting the Direct Use of Data from Traffic Radars and Video-Cameras with Traffic Simulation in the Estimation of Road Emissions and PM Hotspot Analysis ... 28 v Chapter overview ................................................................................................................ 28 3.1 Introduction ..............................................................................................................................28 3.2 Materials and methods ............................................................................................................31 3.2.1 Study area and data collection sites ..................................................................................................... 31 3.2.2 Data collection and processing ............................................................................................................ 32 3.2.3 Traffic simulation ...............................................................................................................................

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