Emission models for freeway traffic systems

It is widely recognised that road transport is one of the main sources of air pollution and that the measures to reduce pollution need to accurately take into account the contribution of road traffic systems. The definition of models for estimating chemical and thermal pollutants produced by vehicular traffic has been investigated by researchers for some decades. The existing models can be classified according to different aspects, such as the geographical scale, the model accuracy and the nature of the approach for computing emissions. However, in the wide range of existing models, only few are suitable for being integrated in management and control tool scheme for freeway traffic systems. These models must be simple enough to be adopted in online control applications but, at the same time, they have to provide a rather accurate estimation of pollutant emissions.