Congestion and Emissions Reduction in Freeway Traffic Networks via Supervisory Event-triggered Control

This paper proposes an innovative control scheme for regulating traffic in freeway networks via ramp metering in order to reduce congestion and traffic emissions. The control scheme is composed by a supervisor, acting at a higher level, which receives measurements from the whole network and periodically makes a prediction on the system evolution, and by local feedback controllers, acting at a lower level. These latter are extended PI-ALINEA controllers which compute the control action not only on the basis of measurements immediately downstream the on-ramp, as in standard PI-ALINEA, but also on the basis of other measurements or predictions referred to farther locations which are time-varying and communicated by the supervisor. The supervisor decides when the control law of extended PI-ALINEA controllers needs to be changed according to an event-triggered logic.