European railway traffic management system validation using UML/Petri nets modelling strategy

Abstract

The European Union set up a European management system for rail traffic: the ERTMS system to ensure, in full safety, train circulation on different European networks. As the full deployment of this system is long and expensive, evolutions are necessary and raise other technological challenges. The goal is to determine how to use ERTMS specifications to produce test scenarios. This paper presents methods, models and tools dedicated to the generation of test scenarios for the validation of ERTMS components based on functional requirements. The development of ERTMS system requires adequate methods for modelling and checking its behaviour. Evaluation and certification of the system can be done by generating test scenarios applying formal methods. The Unified Modelling Language (UML) is a widely accepted modelling standard in industry. However, it is a semi-formal language and it does not allow verification of system behaviour. In this case, formal models like Petri Net can be used. These methods are used in order to formalize ERTMS specification. Tests scenarios are generated on the basis of Petri net models. One scenario is considered like a firing sequence in the reachability graph of the Petri net. Then, test scenarios are applied on ERTMS platform simulator in order to check the components and to give test verdicts. Finally, the approach, developed in this paper, has been applied to ERTMS components in order to demonstrate the validation and certification costs reduction and also to minimize the upgrade and retrofit constraints and validation cost.