The Impact of Exhaust Emission from Combustion Engines on the Environment: Modelling of Vehicle Movement at Roundabouts

Abstract

Due to the increased emission of harmful exhaust components, in particular CO2 (carbon dioxide), CO (carbon monoxide), THC (total hydrocarbons), by motor vehicles, especially in the centres of urban agglomerations, it is necessary to create traffic simulation models that allow to estimate the emissions from road transport. One of the places where the largest accumulation of vehicles in cities occurs are intersections. This contributes to increasing the number of stops and repetitions of the acceleration and braking cycle, which has a direct impact on vehicle emissions. At the same time, roundabouts are intersections with specific traffic movement characteristics, therefore it is necessary to calibrate the simulation model beforehand. The aim of the study was to develop a methodology for modeling vehicle traffic at the roundabout and compare the combustion engines emissions resulting from vehicle movement on the example of the selected roundabout case studies. Vehicle traffic modeling was performed in the Vissim traffic microsimulation program based on real data. The comparison concerned the emissions for a two-lane and a turbo roundabout for the assumed traffic volume scenarios for properly calibrated simulation models. The results show that the performance of the simulation allows for the analysis of emissions and determination of its size for each of the roundabout inlets. It is also possible to determine the general dependencies e.g. the length of the queue of vehicles in relation to the emission of the analysed exhaust components. The analysis can be used as an introduction to changes in the guides for designing road intersections concerning vehicle emissions.