Impact assessment of road fleet transitions on emissions: The case study of a medium European size country

This paper aims to examine the impacts of fleet composition changes on emission due to the introduction of different road transportation policies in a medium size European country (Portugal) applying an ex-post analysis (e.g. policies based on fuel pricing, car scraping, car taxation). A baseline scenario was compared with a counterfactual scenario in order to understand what would occur in the absence of the introduction of those policies. For each scenario, four approaches were assessed using economic effects and/or human health costs. HC, CO, NOx, PM and CO2 emissions from passenger cars and light duty vehicles were evaluated. The results show high statistical significance (p≤0.05) between CO emissions and different vehicle features as vehicle age, fuel type and engine classes. The same pattern was observed between the average vehicle age and HC, NOx and PM. After the implementation of road traffic policies, the average emission factors of the fleet decreased 28-62% for HC, CO, NOx, PM and 20-39% for CO2. However, if a counterfactual scenario would be implemented, the reduction would be 20-80% and 26-55% higher, respectively. The results demonstrates that although were recorded some benefits, the fleet characteristics distribution were more environmental friendly in 2001 than in 2011.