Modelling the effects of transport policies on air pollution

Transport policies can have significant impacts on the environment. This work analyses the extent to which some policies and future trends would influence local levels of air pollution concentration in an urban area. The analysis is based on the application of a road traffic assignment model, in conjunction with an air pollution dispersion model, to the urban road network of Chester, England. The former model simulates the traffic flow conditions, whereas the latter estimates the concentration of five main traffic pollutants at receptor points around road junctions. Actual vehicle exhaust emission rates are input into the dispersion model, as a function of fuel type, fitting of catalytic converters and typical driving operating patterns. Changes in pollutant concentrations are estimated from the implementation of a pedestrianisation scheme in the central area. Furthermore, the effects of traffic growth and the increasing participation of diesels and catalysts in the vehicle market are analysed.