Speed Control of a Highway by Batches Petri Nets as Mesoscopic Models

Variable speed limit (VSL) control, combined with ramp metering, is one of the most efficient real time strategies to substantially improve traffic flow and reduce the congestion problem in road transportation systems. One way to design control strategies applicable in real time is to represent the vehicle flows with a hybrid dynamic model. Mixing flow models and discrete event approach, a batch model has been defined allowing the mesoscopic model to be simulated. This hybrid model, integrated in Petri nets formalism, leads to a drastic reduction in computational effort relative to discrete time or pure discrete event approaches. In this paper, a portion of the A12 highway in The Netherlands is studied thanks to this batch PN model. This hybrid representation leads to evaluate by discrete event simulations, several real time VSL control laws in accordance with the accumulation front of vehicles.