Efficient use of multi-constellation EGNOS for the European Train Control System

Abstract

Exploitation of GPS based EGNOS and Galileo for safe train position determination within the modernised European Train Control System (ETCS) belongs currently among main priorities of the European joint GNSS and rail R&D. It is obvious that only the effective use of the aviation EGNOS SoL service according to CENELEC railway safety standards has the potential to replace costly ETCS track-side balises with much efficient Virtual Balises. This paper deals with optimization and justification of the ETCS Virtual Balise (VB) safety requirements for GNSS with the intention to meet them preferably by means of existing single-constellation EGNOS V2.The optimization has been achieved through the LocationDetermination System (LDS) with the reactive fail-safetyarchitecture. The applicability of EGNOS V2 for the ETCS LDS with a single-channel structure has been justified by means a socalled Travelling Virtual Balise (TVB). It has been quantitatively demonstrated by means of the TVB that employment of EGNOS V2 together with rapid and independent EGNOS diagnosis based on safe ETCS odometry and other techniques is able to meet SIL 4 requirement for the LDS at a system level. Galileo as a second constellation within future EGNOS V3 can be effectively used for the availability of integrity improvement.