Coordinated signal control for urban networks by using MFD

Dynamic Traffic Management (DTM) is preferred rather than the construction of new roads to increase traffic performance. This is because space is scarce and costs are high. Typical DTM measures implemented today are for example ramp metering, traffic signal installations, and variable message signs. DTM measures are usually not coordinated and thus have no interaction with each other. It is possible that DTM measures solve a problem locally but create another problem elsewhere in the network. Then, those DTM measures should be coordinated in order to reach a better performance. Coordination of all measures can be computationally expensive. To manage the scale, a hierarchical approach can be considered in which an upper level control calculates the desired traffic states in the subnetworks it is responsible for. Recently, empirical evidence is found that the traffic state of an urban road network can be described by a diagram with a constant shape: the Macroscopic Fundamental Diagram (MFD). The MFD gives the relation between accumulation (number of vehicles in a network) and the weighted flow in the network. The flow is weighted according to the length of the link it is measured.