2.1.1. Barcelona Traffic Model

Within the city of Barcelona, the Departament d'Estratègia de la Mobilitat has developed/provided a pre-existing meso-scale traffic model using the commercial software package TransCAD® [19]. For this meso-scale traffic model, the road network was divided up into road sections referred to links and each link had a wealth of properties relating both the physical characteristics and imposed rules parameters of the road including, but not limited to speed restrictions, number of parking maneuvers per hour, and lane capacity. Upon addition of all the required parameters within TransCAD®, the model can evaluate how the road network performs. Figure 2 shows the extent of the Barcelona traffic model and the relative speed reductions that are calculated by the model under normal operating (dry weather) conditions. In this figure the %Speed Difference (Equation (1)) refers to the calculated/modelled speed of the vehicles derived from the TransCAD® software, relative to the "Free Flow Speed" (the speed at which a vehicle could move along the section unimpeded by other vehicles). The figure highlights the high levels of congestion within the heart of the city and through the major roadways along the outer perimeter in the modelling result.

$$\% \text{Speed Reduction} = \left(\frac{Speed\_{\text{Modellad}} - Speed\_{\text{FreeFlow}}}{Speed\_{\text{FreeFlow}}}\right) \times 100,\tag{1}$$

**Figure 2.** Percentage speed reduction of traffic in meso-scale model with respect to free-flow speed.
