The Technical Specifications for Interoperability (TSIs) define the standards set by the EU for cross-border rail services in Europe. The individual TSIs relate to subsystems such as infrastructure, energy, control command and signalling (both trackside and on-board subsystems), operations and traffic management, maintenance and telematics applications. In order to facilitate cross-border traffic and promote the modal shift policy, Switzerland aims to adopt the TSI for the standard-gauge main line as far as possible. Switzerland notifies the EU of exceptions in the form of Notified National Technical Rules (NNTRs). The TSI requirements are reduced for the branch lines of the standard-gauge network and do not apply to narrow-gauge railways. The details are set out in the Railways Ordinance (RailO).
