Application of the macroscopic fundamental diagram theory for area control strategies simulated in urban road networks

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. Then each MFD has been used to implement a soft access control strategy for each network model, based on control plan modification of the monitored signalized intersection. The test model has been used to evaluate two methods implementing the access control. First, simplified ON/OFF method was implemented, where the ON is limited to allow a free - flow condition and the OFF to bring the flow from capacity back to a halfway value in the free flow condition of the MFD, decreasing the green time for the relevant approach. The second method (μ method) computes the green time decrease of the modified control plan considering the network capacity as obtained by the MFD and the saturation flow (μ) estimated for the approach of the road intersection, identified as a relevant access for the area. The microsimulations results showed that the second method of access control performs better to solve traffic congestion problems, since it embraces both MFD and the characteristics of a signalized intersection. For this reason, only the μ method has been implemented in the 22@ District network model. The final simulation results proved the effectiveness of the application of a MFD to determine a properly defined traffic control strategy, which reveals its main benefits for the protected area when the traffic congestion level is relevant. In fact, it has been seen that the access control shows its benefits when the protected area is in a gridlock condition, in contrast to when it is simply at a capacity condition. Besides when the traffic control strategy is on, it has been seen that users save almost 2 minutes of travel time in the protected area with respect to the non-control case.