Since the 2013 revision of the Railways Ordinance (RailO), Switzerland has on several occasions amended its regulations governing standard-gauge railways to comply with updated EU requirements. In accordance with European Interoperability Directive 2016/797, individual states must lay down binding notified national technical rules (NNTRs) or binding national specific cases if their national regulations do not comply with the corresponding technical specifications for interoperability (TSl). These NNTRs or specific cases must be published and made available to all infrastructure managers and railway undertakings, vehicle keepers and conformity assessment bodies. Applicants are required to prove that their subsystem complies with the TSI and their NNTRs or specific cases.
NNTRs are national requirements that differ from or supplement a TSI.
Specific cases are special requirements which are different from the requirements in the TSI and which arise for a rail system or its subsystems because of specific national conditions (including geographical, topographical or urban environment constraints).