Improving the efficiency of traffic operations along arterials is currently a priority for many agencies as their roadway infrastructure is built out to the largest possible capacity within the urban environment. Many advanced systems are being implemented to optimize traffic signal timing. Air quality is typically not a consideration when these decisions are made. The relationship between exposure to air pollution and traffic signal timing has not been fully explored by other researchers. This

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... study is the first research effort to combine detailed traffic signal timing data (at 5 second intervals) and air pollutant exposure data. Results show that longer green time along the busy arterial reduces pollutant levels, while increased volume per cycle increases pollutant levels. This research quantifies the factors that contribute to pedestrian, bicyclist, and transit user exposure at a busy intersection along an urban arterial. The factors include traffic signal timing, weather related variables, traffic volumes, and heavy vehicle and bus presence. Additionally, the impact of an adaptive traffic signal system on air quality is assessed to understand the implications of signal timing on air pollutant exposure. ii Dedication This thesis is dedicated to my family, my boyfriend, and his family for always supporting and believing in me, even when I didn't think that I could do it. Having such a wonderful support system helped me stay focused and finish my thesis. To my mom, dad, and sister, for constantly being my biggest supporters throughout my life, I thank you immensely. To my boyfriend Adam, for being the one person in this world that knows exactly how to get me through the hard times and put everything in perspective, I don't know how to thank you enough. To the Furman's, for wanting the best for me and helping me to achieve it. iii