Through strategic documents, directives, and regulations, the European Union has established a broad legal framework for the development of railway track access charges (TAC), which serve as an important instrument for regulating the railway services market. The determination of the structure, economic principles, and level of TAC is defined within a wide framework, resulting in considerable heterogeneity in TAC structures across countries. This paper analyses the extent of heterogeneity in TAC structures among the countries of the Single European Railway Area. Through comparative descriptive analysis, the researchers explore the structure of TAC applied in small railway systems. The research shows that the diversity of TAC structures arises from a range of factors, including differing timelines for the restructuring of national railway systems, the financial capacity of state budgets, geographical positioning, the technical condition of infrastructure, as well as conflicting objectives among transport market stakeholders. The findings underscore the importance of harmonizing TAC structures and offer guidance to infrastructure managers and policy makers in designing more transparent and effective TAC structures and to enhance the comparability and competitiveness of small railways in Europe.