Assessment of Urban Traffic Emissions in Relation to Vehicle Fleet Structure

This paper analyzes pollutant emissions generated by urban road traffic in relation to the structure of the vehicle fleet. The study uses COPERT in order to quantify the contribution of different vehicle categories based on fuel type and emission standard under representative urban driving conditions. Fleet composition was derived from vehicle registration statistics, disaggregated by fuel type and emission standard, while annual mileage was allocated per vehicle category using an age-dependent activity algorithm reflecting the relation between vehicle age and average traveled distance. The methodology combines vehicle fleet distribution data with category-specific emission factors to estimate total emissions for a baseline scenario. Based on this, alternative scenarios are developed, including accelerated electrification of the fleet and fleet renewal through the replacement of older vehicles with those complying with more stringent emission standards. The main scope of the study is the comparative assessment of these strategies, all derived from the same baseline, rather than the provision of a precise inventory of current emission levels, in order to evaluate their relative effectiveness. The results highlight the significant influence of fleet composition on urban emission levels and show that emission reductions depend strongly on both the rate of electrification and the removal of high-emitting, older vehicles. Electromobility adoption is the proper solution for tailpipe CO2 mitigation, while a significant reduction in pollution can be achieved by fleet renewal.