In order to harmonize the different train control systems deployed in Europe and to optimize traffic efficiency by dynamic train control, the International Union of Railway introduced the European Rail Traffic Management System (ERTMS). It relies on two major components: the GSM-R (GSM-Railway) sub-system which ensures wireless communications between the train and the control center and the functional sub-system identified as the European Train Control System (ETCS), which ensures train control by defining the signaling exchanged with control centers via the GSM-R technology. The deployment of ERTMS is mandatory along European Railway corridors through a long and expensive process. Meanwhile, both subsystems may be subject to evolutions. The impact of these evolutions should be evaluated prior to their implementation. Thus, there is a need for faster roll-out and reduction in cost for the certification and authorization necessary to put equipment into service. One of the solutions to accelerate the process relies on making intensive use of lab-testing before real deployment. In the existing ERTMS simulators, all major ETCS functionalities are implemented, but the telecommunication subsystem is not actually modeled. As a consequence, no impairments on the communication technology can be taken into account for the system evaluation. In this context, the VEGAS project aims at designing, developing and evaluating a virtual laboratory based on co-simulation involving two kinds of simulators. The first one is an ERTMS simulator that models the functional behavior of the system. The second one is a telecommunication simulator that enables the modeling of data exchanges over the global telecommunication system architecture including any kind of telecommunication technology. The co-simulation will permit to evaluate the functional subsystem performance while taking into account the impairments related to the telecommunication subsystem, namely the GSM-R (radio propagation impairments such as bad radio links, cuts, electromagnetic interferences or attacks and also network overload). The VEGAS lab will allow a deep study of the behavior of ERTMS components in case of specific dysfunctions or in case of an increase of traffic load in the telecommunications subsystem. With the obtained results, the railway stakeholders and the researchers will be able to elaborate specific procedures in order to reduce the impact of the dysfunctions on the lines equipped with ERTMS. Railway Industry will benefit from a tool that enables the evaluation of the impact of the dynamic telecommunication network behavior on the ERTMS performance. The virtual lab will allow defining a larger range of realistic scenarios with highly reduced costs and with an accelerated process. When several prospective technologies will be considered for an ERTMS component, the virtual lab will allow users to decide which ones are the more relevant and have to be considered for further evaluations based on trials on real sites. The development of the VEGAS virtual lab requires a first phase to define the concepts and mechanisms for co-simulation and the development of a relevant co-simulation protocol. It will determine how specific data must be generated by each simulator, and how these data will be exchanged between the simulators. This phase will permit the development of the necessary tools to open the ERTMS simulator to other simulators. After the implementation of the telecommunication network such as GSM-R including Euroradio, it is necessary to define and to automatically generates the scenarios for tests but also to define the relevant metrics. The different modules of the VEGAS virtual lab will be evaluated with real ERTMS traces. Furthermore, the evolution towards emerging telecommunication technologies such as LTE-Advanced will be possible. At the end of the project, the recommendations for an evolution of the VEGAS virtual lab to evaluate ERTMS level 3 will be set up.

When a train crosses a border, it will need to change its onboard signalling system for example, which will generate an important financial cost. Interoperability of the rail system within Europe is therefore key to its competitiveness. It aims at creating a rail network allowing transport that is safe, compliant with the required performance level of the lines, and which does not necessitate train transfers. This requires the compliance with a set of rules, of technical and operational conditions which ensure that the essential requirements are met. The present project aims at contributing to the validation and implementation of a European system for railway signalling called ERTMS “European Rail Traffic Management System”. The management of railway signalling in ERTMS is based on local rules pertaining to each country and not on global rules. This makes it difficult to evaluate the system in terms of safety. Thus, one of the main objectives of this study is to supply methodological tools for the evaluation of the global consistency between the specification and the operating rules, with regard to safety. This issue is crucial and yet it has scarcely been covered by scientific literature. A formal representation of the ERTMS specifications will be provided, which will enable the validation various systems through automatically generated test scenarios. • These systems will be modelled and studied in order to establish, if possible without having to test, whether they are compliant with ERTMS • The national rules complementing ERTMS will be included in the study. Achieving interoperability through ERTMS requires that all parties have the same understanding of the technical specifications for interoperability. Using a model featuring rigorous semantics will help identifying and clarifying ambiguousness in the specifications. A first step will therefore be to build a formal model based on complex requirements taken out of some rules. It will then be possible to analyze in details a European specification in the face of national operating rules, for example with regard to the execution of a Movement authority (MA). An actual specification, proposed by the railway company, will be analyzed in work-package 1 (The ERA or EPSF will be asked to provide an initial specification). The French Public Railway Safety Authority (EPSF) is competent in railway security matters whiles being independent from railway operators. A second step will provide a study of methodological and software tools in the literature. Formal models will be used to determine whether a given scenario meets the specifications. The respect of the European system requirement specifications (SRS) and of national safety requirements will be studied, on the level of models as well as analysis tools. In a last step, a study will be based on tests on an ERTMS simulation tool compliant with the official specifications. The possibility of making the two work together in an integrated approach will be studied.