RUNE (Railway User Navigation Equipment): Architecture & Tests

Due to European on-going developments (EGNOS, GALILEO), satellite navigation is now an interesting innovation for all fields of transport. One of them is the railway domain, which could considerably profit from the implementation of autonomous on-board positioning systems. For railway transportation, satellite navigation offers new opportunities to increase accuracy of positioning and to implement safety standards everywhere, from high speed trains to local and regional railway lines, enabling a cost-effective modernization and increase of efficiency. Train control poses high demands on positioning with respect to availability, reliability and integrity. Meeting these requirements with a GNSS-based navigation system is the objective of several projects and still needs to be proved.

RUNE is a project developed for the European Space Agency by Alcatel Alenia Space Italia (Laben Directorate), leading a team comprised of VIA Rail Canada Inc. (VIA), Ansaldo Segnalamento Ferroviario (ASF), and INTECS HRT. In this project, the European Geostationary Overlay Service (EGNOS) has been used as part of an integrated solution to improve the train driver's situational awareness.

RUNE integrates positioning sensors with signalling and speed constraint information from a control centre. This can improve safety as a result of a better situational awareness and can also speed up the deployment of drivers on new routes. The primary objective is to demonstrate the improvement of the train self-capability in determining its own position and velocity with limited or no support from the track side, still complying with European Railway Train Management System (ERTMS) requirements. The achievement of such objective could lead to the reduction of physical balises distributed along the track line and needed to reset the train odometer error. Substituting physical balises with GNSS-based virtual balises can lead to reduction of infrastructure costs.

The RUNE project development has gone through a HW-In-the-Loop laboratory set-up up to field-testing. Field tests of the equipment were performed in Italy on the Torino-Chivasso line in April 2005, on board a Trenitalia ALE-601 experimental train. The unit included an LI GPS/EGNOS receiver, Profibus and CTODL interfaces to the train odometer and BTM, an IMU sensor for dead-reckoning positioning, virtual balise and velocity profile databases. This paper presents an overview of RUNE and provides results of the analysis performed on the data collected from the experimental train test campaign. Although testing duration was limited, collecting and analysing real data is important for building expertise in system behaviour and for algorithms evaluation and tuning. Those initial results show achieved performance in the real environment and the capability of the system to provide In-Cab Signalling and Virtual Balise functionalities. It is recognized that only through extensive field testing and validation of the system architecture and algorithms it will be possible to build a robust certifiable GNSS-based train navigation system.