Improving the efficiency of urban traffic operations along arterials is a priority for many agencies because congestion has an impact on the people and goods movement in many cities. Advanced traffic management systems are being implemented to optimize traffic signal timing in congested corridors. Pedestrians and transit users are greatly exposed to vehicle emissions, even more than drivers themselves. However, pedestrian exposure to traffic emissions is typically not a consideration when traffic signal timing decisions are made. The relationship between exposure to air pollution and traffic signal timing has not yet been fully explored or modeled. This research quantifies the factors that contribute to sidewalk level particulate matter (PM2.5) concentration levels at a busy intersection along an urban arterial in Portland, Oregon. This study is the first research effort to combine real-world detailed traffic signal timing data (at 5 second intervals) and air pollutant concentration data. Several types of variables are included in the statistical analysis: traffic signal timing variables, weather related variables, traffic volumes and composition variables, and variables associated to bus presence and characteristics. Statistical results show the importance of signal timing variables, traffic volumes, and queuing.
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