A Formal Approach for Railroad Traffic Modelling Using Timed Automata

The present paper proposes a new modelling framework well-suited to describe in detail multiple modelling features and interactions among different components of railway transport systems. Timed automata and Uppaal software tool were chosen because allow not only the introduction of additional features but also the construction and the verification of timed models. Another important advantage of the presented formalism is given by the possibility to operate modifications on the simulated maps only by changing the initialization variables and without changing the UPPAAL model. Different templates were defined to represents the complexity of railroad train station, two types of structures being taken into consideration: infrastructure – road, switches, traffic lights, platforms, and moving vehicles – engines, cars. To model and analyze the two types of structures, a two layered model based on Timed Automata was considered; one represents the components of the infrastructure and the relations between them and the second one represents the mobile components of the railroad traffic. The interactions between layers were defined using a set of rules implemented in “C” programming language. A case study was considered for simulation purposes, some possible scenarios being presented. A list of queries was generated in order to verify various properties. The proposed framework proved to be capable to model railway complex structures and to verify their behavior.