In 2000, TRL was commissioned by the Department for Transport to investigate the effects of various types of traffic management scheme on exhaust emissions from trucks and buses. To achieve this, 50 heavy duty vehicles covering a range of vehicles types, weights and emission legislation were driven over various traffic management and regulated driving cycles on a chassis dynamometer whilst their emissions were measured. The data collected was used to develop a predictive emission model for the evaluation of planned and existing traffic management schemes. The test programme also allowed an in depth investigation of the emissions performance of heavy vehicles, including unregulated pollutant emissions. The model used a subjective approach where a proposed scheme could be defined using a series of photographs of similar road layouts which are selected from a database within the model. The photographs are linked to emission factors for different vehicle categories, and emissions from traffic through the scheme to calculate emission factors. These are weighted by traffic flow and composition information provided by the user to calculate overall emissions. This approach enabled those with limited information on cycle characteristics to use this type of model. (A)

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