The aim of this thesis is to investigate the existence of a Macroscopic Fundamental Diagram (MFD) and its application to support possible traffic control strategies to mitigate congestion in urban road networks. Two different traffic simulation models have been used as case studies representing urban scenarios in the city of Barcelona. The first network model, located in the neighborhood of the Camp Nou Stadium, is used as a test model because of its reduced extension. The second network model, placed in the 22@ District (Poblenou), represents an extended area and it is a traffic system calibrated with real traffic data. Through the application of different microsimulation experiments in the two network models, a MFD has been generated for each road network systems, validating the existence of a network fundamental diagram for the two areas of Barcelona.