Estimation of future emission scenarios for analysing the impact of traffic mobility on a large Mediterranean conurbation in the Barcelona Metropolitan Area (Spain)

Emission modelling permits us to quantitatively assess the effects of emission abatement strategies. In urban areas, such strategies are designed mainly to reduce the emissions from the on–road traffic sector. This work analyses the impact of several mobility strategies on urban emissions in the coastal city of Barcelona, Spain, when the High Elective Resolution Modelling Emission System (HERMES) is applied at a very high resolution (1 km × 1 km and 1 h). The analysis was conducted by projecting the emissions data obtained from a base case scenario in 2004 onto three future scenarios set in 2015, where each future scenario represented a set of traffic mobility management measures. Specific developments were considered per emission sector, including power generation, industrial activities, domestic– commercial, solvents, on–road traffic, biogenic emissions, ports and airports, to best compare the present base case scenario with the future mobility scenarios generated for 2015. These emission scenarios for 2015 take into account the population projections and the variations in port and airport activities among other factors, while the main focus is on the on–road traffic sector, the types of vehicles used, such as technologically improved buses and hybrid vehicles, as well as the types of fuels used, including natural gas and biofuels. The results of the emission model indicate that the mobility management strategies, the technological improvements and the use of alternative fuels reduce the emissions from on–road traffic by approximately 75% (in terms of nitrogen oxides emission reductions in the city centre of Barcelona). This decrease leads to a 35% reduction in overall nitrogen oxides emissions, even if some sectors individually experience increases based on their specific projections.