ERTMS. European rail traffic management system. Strategic program for research and development of the railway industry, sponsored by the European Union (DG-TREN, V.), with the aim of constituting the bases of a future system of command, control and coordination of railway circulation, through technological solutions unified on the basis of a general concept of “interoperability” between networks. To this end, ERTMS is based on advanced train gear control/monitoring devices, on ground/board radio communications and on a set of standard procedures for managing information between different command/control centers, as well as between these and the staff of train conduct. As such, the ERTMS represents a framework project in which, to the safety systems of traffic management (distancing), supervision and control activities (traffic optimization), transport planning and the entire cycle of operations proper to traffic must be integrated, as well as railway operation, up to the highest levels of coordination. The development of the ERTMS downstream of the preliminary studies, always conducted in the European ambit on traffic control systems (ETCS: European Train Control System), provides for 3 levels of operability (L1, L2, L3) with standard technologies. L1: foresees minimal ERTMS technologies, without interface with on-board operator (driver). L2: provides ERTMS technologies together with traditional technologies, with interface with on-board operator (driver) and with train-managed integrity on the ground. L3: only ERTMS technologies, with interface with on-board operator (train driver) and train integrity managed on board, all to harmonize the procedures and organizational processes of the various Networks, in view of a common railway system. A particular aspect of interoperability also concerns the standardization of regulations and exchanges of messages (voice and/or automatic) between train conductors and personnel in charge of the Central Operative Management, in order to establish a unified system of information, protocols and behaviors that is common to railway operators throughout Europe. The ERTMS specification provides a command/control system that aims to ensure safe control of train movements, based on an exchange of information between land and board through multiple information channels, of a discontinuous type with balises (information points) and continuous type with radio (GSM-R). The ERTMS is based on three levels that define technical conditions of increasing level of realization of the required functions. All levels provide safe supervision of temporary speed control, permanent and dependent on train characteristics. The main aspects of the three levels are described below. – The First Level (L1) is the integration of an information system that uses buoys (EUROBALISE, Transponder) and/or “loop” cable circuits (EUROLOOP), superimposed on an existing signaling system; this requires the introduction of Specific Transmission Module (STM) interfaces capable of translating the information on the control systems already existing on the line into ERTMS format, as well as an on-board equipment capable of converting the information drawn from the STM and presenting it to the on-board system (EUROCAB,). This First Level has the objective of increasing operational safety in any environmental condition of the road, transmitting on board secure information on the status of the signals on the ground, by means of the discontinuous and continuous channels which repeat on board the appearance of the signals imposed by the system of distancing present on the ground, and provide timely and geographical information on the route (start and end of the controlled area, slowdowns, PL, crossroads, etc.). The same level allows you to travel at the maximum speed allowed by the characteristics of the track and the train, implementing a safe speed control, in accordance with the infrastructures present, based on the distance between two consecutive signals. In this first level the use of the man-machine interface, Man Machine Interface (MMI), on board the train is optional, and depends on the choice between technical interoperability or operational interoperability; in this context, in the event of a discrepancy between the lateral signaling and the information given on board via the MMI, the legislation will establish whether the driver must obey the existing signaling or the information given by the on-board computer. The integrity of the train (Assessment of completeness) is verified by the existing ground systems. The Second Level (L2) provides for the implementation of signaling systems that control the distance of trains in full line and the same equipment introduced in the first level can be used; the innovative man-machine interface (MMI) is mandatory and provides to give the driver both the orders related to the march and the information related to the line. This makes it possible to safely manage traffic even in the absence of lateral signaling, automatically adjusting the speed allowed for the train, based on the information provided at any time, through a continuous transmission system, RBC (Radio Block Center) from the existing ground-based spacing system to fixed sections. This allows a safe speed control in predictive mode, because the information relative to the location of the stop or slowdown point is transmitted to the train in real time, that is, as soon as it is processed by the ground blocking system and, therefore, in an anticipated way with respect to what can be done with the side signals, located at a certain distance from the train. In this second level the discontinuous channel, through the buoys, provides only punctual geographical references and the train integrity is still verified by existing cdb devices. – The Third Level (L3), in addition to the first two, provides for the mobile Block based on the train’s auto-localization and uses, as for the second level, a continuous ground-to-train transmission, via a radio channel, EURORADIO, which centralizes the information in a Radio Block Center and therefore provides information on board the train distancing. In this case, too, the discontinuous channel provides only point references. This third level allows the train to run safely in complete absence of the side signaling; therefore, it fully implements the operational interoperability required for the European standardized march. The third level also provides, unlike the other two, the on-board train integrity check function by means of appropriate devices, Train Integrity Interface (TTI), which is able to carry out the completeness checks of the train. The purpose of this level, in addition to the safety levels ensured by the previous ones, is to maximize the potential of the line by minimizing the distance between trains and, consequently, increasing the capacity of the entire railway infrastructure. The ERTMS system architecture consists, in summary, of a common central part, ERTMS Kernel, which manages the safe control of the train speed, and from different modules, STM, of interface between the train and the existing signaling systems to land. The definition of on-board equipment, necessary for the construction of ERTMS, is developed in the sub-project called EUROCAB; the ground equipment consists of balises (EUROBALISE) for a point-based information system (discontinuous), cables placed in the middle of the rails (EUROLOOP), for a continuous information system, and radio channels (EURORADIO), for a continuous information system without the need for traditional locking systems and side signals. The so-called Level 2 is defined for the new Italian system of high-speed lines. The final objective of the ERTMS is to achieve complete operational interoperability, which allows trains to cross European borders without having to request the driver to be changed and based on common driving rules
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