A model of air pollution from road traffic, based on the characteristics of interrupted flow and junction control: Part II -- model results

In Part I of this paper (Matzoros and Van Vliet, 1992) the theoretical basis of a model which predicts air pollution emissions and concentrations from urban road networks was presented. In this part that model's results and sensitivity analysis are laid out. The model was tested under a wide range of conditions to pinpoint the variables that most affect its results in single links and real networks. Both pollutant concentrations at a range of receptor points and total link/network emissions were calculated and used in the comparisons. Link flow and capacity were identified as the two variables with the greatest effect. The location of the receptors with respect to both their distance from the roadway centerline as well as from the junction stop line was also found to be critical. Other important variables were wind speed and direction, while input emission rates had a linear effect on computed concentrations. The cycle time of signalised junctions had a variable effect on concentrations. Comparisons of modelled and observed values were made and are briefly reported here. The peakiness of the emission and concentration distributions of the pollutants was demonstrated using appropriate figures for both signalised and priority intersections. The model is intended to be used by traffic managers and transport analysts for scheme design and evaluation and for pollution prediction from road networks.