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

A computer model has been developed to tackle the problem of transport air pollution from urban networks. It consists of queueing, emission and dispersion models and takes vehicle operating modes (cruise, deceleration, queueing and acceleration) and their variable emission rates into account. Queue lengths at signalised, priority and roundabout intersections are specifically modelled. In this way the model predicts the spatial variability of emissions on urban roads: high pollution near junctions, levelling off towards mid-link points. The dispersion model uses empirical modifications to gaussian diffusion theory in order to account for the effects of moving vehicles on the turbulence of the air masses surrounding the roads. The model takes traffic data, emission rates and meteorological data and outputs air pollutant concentrations throughout a network in numerical and graphical form. The modelled pollutants are carbon monoxide, hydrocarbons, nitrogen oxides and lead. The model does not handle photochemical pollution.