Integration of Global Navigation Satellite System (GNSS) and telecommunications (TLC) is without questions powerful instrument enabling safety improvement and operational efficiency. It is only a question of a short time, when the first GNSS based signaling conformable with the CENELEC railway safety standards (EN 50126 [1], EN 50129 [2], etc.) will be introduced into railway operations. This paper summarizes main results achieved within the ongoing ESA 3InSat project (2012-2014). They include: 1) railway user safety and dependability requirements specification and allocation to the train Location Determination System (LDS) based on GNSS, 2) demonstration of benefits resulting from employment of GNSS multi-constellation (GPS, GLONASS, Galileo/ Beidou) for the ERTMS/ETCS safety targets fulfillment; 3) utilization of local augmentation network (Au-network) including the wide-area EGNOS SoL service for improvement of the safety integrity and reduction of the GNSS position error confidence interval. Finally, the procedure for the LDS safety case elaboration is outlined and the questions regarding the LDS certification with respect to the limited accessibility of EGNOS SoL service Safety Case are also discussed

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