On adopting a petri net-based switching modelling system to represent and control urban areas
Angela Di Febbraro, Davide Giglio · 2005
Deterministic timed Petri nets are a suitable mod- elling formalism to represent signalized urban areas microscopi- cally, when pursuing traffic management and control purposes. In the proposed model, an urban transportation network is considered to be composed of signalized intersections and roads. So as to properly model any traffic condition, including congestion, any intersection equipped with a multi-phase traffic signal is divided into several crossing sections. The modular deterministic timed Petri net representing the overall traffic network allows to implement a switching modelling system. In fact, the representation of some parts of such a Petri net can become more or less detailed, whenever some event modifying the current traffic state occurs. I. INTRODUCTION Nowadays, it is widely recognised that the search for effec- tive solutions to pressing problems of traffic in metropolitan areas is a primary task to perform. In the past decade, urban traffic has known an enormous growth, making the need for new approaches to deal with it critical, in order to spare time, money, and lives. The application of information technologies to model, analyze, and control transportation systems, that is, Intelligent Transportation Systems (ITS), seems to offer promising solutions to the above mentioned problems. In the related framework, the focus is two-folded, on both intelligent infrastructures and intelligent vehicles. An intelligent infrastructure could fulfil transportation needs inside and around cities, whereas intelligent vehicles could complement it by making a real-time traffic information exchange feasible and improving safety. Since the sixties, the flows of vehicles in metropolitan areas have usually been regulated via the implementation of some kind of control on traffic lights. That usually consists in changing, according to the time-varying behaviour of the incoming traffic, the intersection stage specification, the relative green duration of each stage, the intersection