## 7 Conclusions  
Paraphrasing the words of [PERSON] included in one of his books, entitled The Future of Geography: How Power and Politics in Space Will Change Our World, it can be said that signs that space will play a major role in rail transportation of the twenty-first century have been evident for some time. This is evidenced not only by the number of literature items, but also by a number of ongoing projects and studies aimed at developing solutions to implement the functionality of Global Navigation Satellite Systems in railway applications. An example is the described projects APOLO, GADEROS, LOCOPROL, GaLoROI, 3 inSat, NGTC and Shift2 Rail IP2, the assumptions of which were or are aimed at the development of the railway industry in terms of automation and autonomy of the implementation of traffic processes. In the literature relating to the above programs, the authors mostly define the assumptions and guidelines for the implementation of the projects, with little description of the technical assumptions. In this review, the focus is on literature items published in the years from 2000 to the present. According to the presented review cross-section of literature items, the largest trend in the publication of articles on GNSS implementation in railway solutions has been observed since 2015. The above may be due to the fact that in the current period, new projects and programs related to the development of railway systems were launched, among which one of the new areas was the implementation of satellite positioning systems in railways. The above and the apparent development combined with the widespread use of satellite positioning combined with the expansion of the functionality of satellite systems in commercial applications became the basis for reconsidering the implementation of positioning in railway systems. It should be noted that the apparent decrease in the upward trend in the publication of articles on GNSS in railways in 2021-2023 is most likely due to the situation associated with the constraints of the COVID-19 pandemic. In contrast, the trend of publications for mid-2024 indicates renewed interest in the subject area. When considering the possibility of using rail vehicle positioning based on signals from a constellation of space segment satellites, supported by ground segment infrastructure, it is first necessary to determine the area of potential implementation of GNSS in railway infrastructure. Based on the projects and studies carried out to date, it can be observed that the most frequently indicated area for GNSS application is the positioning of rail vehicles for the purpose of moving spacing in ETCS Level 3. For the purpose of running railway traffic, it is necessary to ensure, in accordance with the assumptions of the RAMS criteria, a high level of safety of the system or systems determining the positions of a given rail vehicle in the railway infrastructure. In this context, it should be noted that the criteria for evaluating satellite positioning systems included in the ICAO guidelines differ in terms or have different definitions for converging criteria. The above requires defining the parameters of technical evaluation criteria, consistent for the applications of satellite systems in rail transport, or defining new ones, uniform for both areas. Obtaining the highest possible level of positioning accuracy for rail vehicles requires continuous and uninterrupted transmission of signals between the satellites of the various satellite constellations and the object, which in the case under consideration is a train moving on the railway lines. At this point, it is important to emphasize the importance of using as many independent GNSSs as possible in positioning, in order to reduce the potential risks arising from a temporary or long-term failure of system operation.