On controlling privileged vehicles by means of coordinated traffic lights

The control of urban traffic is one of the most difficult problems to face in transportation research. In this paper, a valuable hybrid model of urban networks of signalized intersections is used to solve the problem of controlling some special classes of vehicles. In particular, the problem of coordinating several traffic lights is addressed and solved by means of a hierarchic control structure by defining simple control algorithms. The experimental applications of the proposed control structure to two case studies, relevant to the Italian city of Turin, are reported and discussed.