Hybrid Petri nets for the performance analysis of transportation systems

A novel hybrid model for transportation systems is proposed, in which the functioning is represented via a continuous-time model whenever no changes in the traffic flow occur, whereas the changes in the system behaviour are modelled through a discrete event system coupled with the continuous-time system, on which acts as a regulator. The hybrid modelling methodology proposed is based on the use of a special class of Petri nets, the hybrid stochastic Petri nets (HSPN). These nets are composed of some discrete parts, and some continuous parts. The discrete part of the HSPN `regulates´ the continuous PN, which models the functioning of the transportation system, making the continuous-time part adapt according to the variation occurred in the system behaviour. As a result, the model reacts to any change in the current system behaviour by adapting the traffic parameters to the new state