I. Introduction
The definition of models for the prediction of the traffic behaviour and the development of control techniques for freeway traffic systems have been relevant research topics for several decades. In recent years, the technological developments achieved in the automotive sector and in detection and communication systems have put into evidence that it is necessary to revise conventional traffic models and control schemes in order to fully exploit the potential of new technologies. In the past decades, a wide range of traffic control strategies have been studied in order to regulate traffic, guaranteeing a more efficient use of the road network capacity, through the minimisation of the congestion and the total travel delay in the system (see e.g. [1]–[3]). Moreover, a new vision of the global improvement of mobility has given rise to the definition of sustainable control strategies aimed to reduce the traffic impact on the environmental system (see e.g. [4], [5] where the designed traffic controllers take explicitly into account the reduction of fuel emissions), as well as to improve traffic safety (see e.g. [6] in which the reduction of the expected number of crashes is accounted for). However, despite the great efforts conduced in this direction, these issues are still far from being completely solved.