Instantaneous emission evaluation: Study into disaggregated models


Type de document
Résumé / Abstract
In order to determine traffic-related emissions and to propose really efficient measures for controlling pollution (traffic ban, country planning, strategy of transport development), a good comprehension of the pollutant emission mechanism is necessary. The pollutants released by the vehicles must be described under real-word driving conditions, thus enabling to determine traffic-related emissions. Emission predictive models, such as the Copert or Modem models, are therefore used. These models are coupled with dispersion models to characterise air quality according to traffic and climatic conditions. Available models provided valuable pollution predictions at a macroscopic scale (at least at town level). They are based on a description of driving behaviours from vehicle average speed, which is a major parameter to describe pollutant emissions. Nevertheless, it should be noted that, in a number of cases, emission levels significantly vary with the driving behaviour, even for close average speed levels. In such cases, the accuracy of the models based on average speed is not sufficient to characterise emission levels at smaller scales (district, street) or to study the impact of a number of parameters, in particular in terms of urban planning (speed reducing devices, green wave, etc.). This memorandum reviews the instantaneous approaches proposed, limited to passenger car cases. The general context of this study is first described. Then, an aggregated model, based on the description of emission matrices is presented. Some model improvements are proposed and the results obtained using this method are then analysed and discussed. These results led to a number of conclusions raising some questions to be further answered.

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