The effect of weather on speed reduction on a freeway and air pollutant dispersion pattern near the freeway

摘要

This paper examines the variations in traffic speed and the dispersion pattern of NOx produced from traffic in clear, rainy and snowy weather conditions. The data used for the analysis include weekday hourly traffic count of 193 days in 1998 on Gardiner Expressway, Toronto, Ontario, and the coincide 193 meteorology days. The ordered logistic regression model was used to identify the relationships between speed reduction and various factors. The EPA emission factor model and AERMOD were used to predict NOx concentrations using traffic volumes and meteorology data. Analysis of speed reduction shows precipitation, hour of day, snowy condition and seasons reduce speed. The predicted dispersion show NOx concentration was high in clear weather condition compared to adverse weather condition due to higher traffic volumes and higher emissions. However, in snowy weather condition, wind speed had more influence on NOx concentration than emission rate