HIERARCHICAL DISPATCHING CONTROL OF URBAN TRAFFIC SYSTEMS

A two-layer hierarchical structure for urban traffic dispatching contr ol is proposed. The upper layer problem is global optimization which i s solved by a central dispatching unit (CDU). It performs resource all ocation in the whole system in accordance with the working conditions in the subsystems. The lower layer problem is local optimization which is solved by local dispatching units (LDUs). They perform vehicle rou ting functions within the respective subsystems. Special procedures, s uitable for on-line control, are proposed for obtaining the upper laye r solutions and for the information exchange between the layers. The b ehaviour of a taxi system is simulated and the positive influence of t he upper layer is shown.