Effect of Vehicular Traffic Volume and Composition on Carbon Emission

Abstract

Road intersection is one of the causes of air pollution or toxic gases emission because at such location vehicular traffic are either required to slow down or completely stop for them to secure a safe and acceptable gap to perform a particular type of manoeuvre. The level of gaseous emissions usually increases with corresponding increase in traffic. The level of the environmental pollution depends on the type of intersection. This study evaluated the amount of carbon monoxide (CO) emissions from vehicular traffic for both morning and afternoon peak periods at roundabout and priority intersections. Carbon monoxide emissions at the intersections were first measured using GrayWolf Sensing Solution (GWSS) upon which the results obtained were used in calibrating SIDRA software for estimation of CO emission. SIDRA emission estimates were derived from traffic flow parameters; traffic volume, compositions, speeds and turning movements, as well as road geometry. Calibration factors were then derived in order to make SIDRA a reliable means for measurement of vehicle emission. Further, CO emissions traffic models were developed for the two types of intersections evaluated in this work for both morning and afternoon peak periods for two different observations periods (5 minutes and 1 hour traffic volumes) using multiple regression analysis. The models developed described how vehicular traffic volume and compositions affect CO emissions at road intersections. Further analysis revealed that roundabout is a better form of intersection as it reduces the amount of CO emission when compared to simple priority intersection.