Estimation of air pollutant emissions in Flower roundabouts and in conventional roundabouts

The road pollutant emissions, above all in urban context, are correlated to many infrastructural parameters and to traffic intensity and typology. The research work on road junction geometry, carried out in European research centres, has recently allowed to design new road intersection types which are of undoubted interest, especially in terms of traffic functionality and safety, like the flower roundabouts (in which right-turn manoeuvres do not conflict with the circulating flow). The main objective of this paper is to propose a model for the estimation the capacity, delay, levels of service and the pollutant emissions into flower roundabouts. A comparative analysis between conventional roundabout and flower roundabout has been carried out in terms of CO, CO2, CH4, NO, PM2,5 and PM10 vehicular emissions, evaluated by mean of COPERT Software which is developed as a European tool for the calculation of emissions from the road transport sector.