Study on pollutant emissions of mixed traffic flow in cellular automaton

Abstract

Based on mixed NaSch traffic flow model and the empirical formula of automobile exhaust emissions, emissions of particulate matter (PM), CO2, NOx and volatile organic compounds (VOC) are investigated with consideration of the different movement conditions, mixing ratios, the maximum velocity and lengths of vehicle. Pollutant emissions are determined by traffic characteristics from free-flow to congestion. Emissions of mixed traffic increase with the mixing ratio increasing. The impact of traffic state on emissions is discussed in detail by introducing the distribution functions for three types of motion states. Results show that decelerating vehicles discharge the most pollutants even if accelerating and decelerating vehicles in the congested state have a great impact on pollutant emissions in the mixed traffic flow. The effect of the maximum velocity and the length of vehicles on emission are investigated, respectively. It is found that the maximum velocity of the short vehicles has a significant impact on emissions when the mixing ratio and length of vehicles are fixed. The larger the maximum velocity of the short vehicles, the more the emissions is, but the maximum velocity of long vehicles does not display obvious effect. When the mixing ratio is given, the longer the vehicle, the less the emissions are due to restrictions on the loop road.