Timetable tracking in a public transport network

Some problems related to modelling and controlling an intermodal urban transportation system are addressed in this paper. The transportation network is modelled as an oriented graph in which nodes represent single-mode or intermodal stations. For the system considered, a discrete event model integrating different transportation services is proposed. Some disturbances are included to model the stochastic nature of the system. Based on such a model, a special-purpose traffic simulator has been designed. It produces the data necessary to solve the optimization problem which has the objective of guaranteeing the regularity of the transportation services, i.e., the fulfilment of the timetable. Due to the presence of a statistically unknown noise, such an optimization problem results in a particular tracking problem, which cannot be solved by applying the dynamic programming. Thus, a heuristic solution is proposed, reporting also some experimental results about its performance.