The European area is more fragmented than any other continent, marked with significant disparities among countries in terms of territorial size, population, and economic strength. This characteristic is also reflected on the national railway systems. European integration processes require uniform rules, particularly in the establishment of a single market, including the railway market. However, this raises the question of whether the same approaches and models should be applied across the board - especially regarding the restructuring of railway systems, defining track access charges (TAC), awarding public service contracts (PSC), and the implementation of interoperability. In addition to the small network size, small national railway systems often face a lack of technical, human, and financial capacities, which requires the process of establishing a single European railway area (SERA). The paper is dedicated to discussing the justification for special treatment for small European national railways and how to identify it.