Conducted within the framework of a CIFRE agreement, this thesis focuses on the legal issues of opening up to competition of the internal passenger rail transport based on observations and studies carried out as part of an immersion within the Rail Department of the Transdev Group. It intends to demonstrate that the diversity of legal and technical requirements which characterize the single European railway area has repercussions on the different access strategies of new entrants. A tangible sign of the persistence of national specificities, the heterogeneity of forms of rail regulation is accompanied by the maintenance of many barriers to entry. The removal of technological barriers (access to rolling stock, to maintenance) and non-technol...