Modeling vehicle emissions

Abstract

The estimation and control of vehicle emissions play an important role in the sustainable development of an urban area. Many studies have shown that without a balance between vehicle usage and vehicle emissions, urban areas will never be able to reach a sustainable development. However, for planning purposes professionals have struggled with the proper modeling and estimation of vehicle emissions in an urban area. The focus of this paper is to present a new modeling procedure for estimating vehicle emissions based on individual vehicle interactions in a traffic stream. The model microsimulates these interactions and then translates them into consequent energy consumption and pollutant emissions. The main feature of this model is that it calculates the effects of transient changes in power on vehicle emissions. It divides power into 34 bins and speed into 20 bins covering the three vehicular events of acceleration, deceleration, and cruise. It does the emission calculation at every second and in 7.5 meters cells and accumulates the results into 30-meter segments and 15 minutes interval. The model takes into consideration grades, malfunctioning vehicles, coldlwarm starts, enrichment cycles, and types of vehicles. It has a running evaporative emissions module and a resting, hot soak, and diurnal evaporative emissions by location. Among its inputs are the EPA's three-cities distribution of speeds and accelerations, The CARB stratified arterial and freeway trajectories, the CMEM model used to construct emission arrays by vehicle type, speed , grade and power bin, West Virginia University truck power distributions and West Virginia University truck and bus emissions. The output shows the emissions in terms of HC, CO, and NOx for each road segment of a link for each time interval.