GNSS is expected to help the railway system to be modernized. However, such localization applications requires a high level of accuracy and safety that deserve to use the best potential of satellite-based technologies. The augmentation systems, as the satellite-based augmentation system EGNOS (European Geostationary Navigation Overlay Service), helps to increase the nominal performance. One of the tasks of the EU STARS project deals with the study of the usability of EGNOS in railway environments. EGNOS has indeed been developed driven by the requirements of civil aviation safety procedures in conditions for signal reception that differ from the railway ones. In this paper, after introducing the needs and the basic principles of these systems, we describe the limitations caused by the specificities of railways and some solutions perspectives proposed by the project.