In order to harmonise the different train control systems deployed in Europe and to optimise 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 centre and the functional sub-system identified as the European Train Control System (ETCS), which ensures train control by defining the signalling exchanged with control centres 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 authorisation 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 modelled. 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 behaviour of the system. The second one is a telecommunication simulator that enables the modelling 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 behaviour 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.
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.
Preliminary results described the co-simulation approach that has been developed in order to design a virtual laboratory for ERTMS functional and telecommunication subsystems evaluation. The models of the GSM-R in OPNET are still being developed, and they will be evaluated using real-world traces of trains moving on ERTMS lines. In future work, the researchers will perform the evaluations of several ERTMS scenarios using the virtual lab, and will introduce new models in order to evaluate other prospective technologies such as LTE.
A paper presented at TRA - Transport Research Arena 2014 is available at the following link https://hal.archives-ouvertes.fr/hal-00985733/document