The diploma thesis examines the roles and tasks of supervision and the notified body in carrying out works on the public railway infrastructure in the territory of the Republic of Slovenia. I also address the role of the public railway infrastructure operator in charge of the rail transport’s safe operation. Information on these three subjects were obtained from the Slovenian and European legislation, which is valid in the territory of the Republic of Slovenia. I also describe the EU directive on interoperability and carry out a benchmark for several parameters of the railway line in line with European and national regulations. In conclusion, I will briefly describe (summarize) the purpose and method of ensuring the directive on interoperability and the differences in parameters followed by it and under national regulations.