Evaluating the Impact of Traffic Congestion on Mid-block Fine Particulate Matter Concentrations on an Urban Arterial

摘要

The primary objective of this paper is to evaluate the impact of traffic congestion on mid-block fine particulate matter (PM_(2.5)) concentrations on an urban arterial. Data of mid-block and background PM_(2.5) concentrations were collected second by second during peak and non-peak hours on an urban arterial. Then micro traffic conditions were extracted from videos at ten seconds intervals, including traffic volume, traffic flow speed and high-duty vehicle fraction. Results showed that traffic volume had significant influence on mid-block PM_(2.5) concentrations. Mid-block PM_(2.5) concentrations were not correlated with traffic level of service. Furthermore, a modified passenger car equivalent was calculated from the aspect of contribution on PM_(2.5) concentrations using multiple linear regressions model. Then a comprehensive model was established to model the impact of micro traffic conditions on PM_(2.5) concentrations. Results of the comprehensive model showed that PM_(2.5) concentrations increased with the increase of total volume or heavy-duty vehicle fraction. Besides, low traffic flow speed resulted in high PM_(2.5) emission factor, leading to the increase of PM_(2.5) concentrations. The findings of this study can help better understand traffic congestion and micro traffic conditions on PM_(2.5) concentrations.