Based on the Directives on interoperability of the rail system within the European Union, the process was initiated aiming at ensuring safe and unhindered rail transportation across member states’ rail systems. The currently valid Directive on the interoperability of the rail system within the European Union (2016/797/EU) and applicable technical specifications for interoperability (TSI) related to specific railway structural subsystems stipulate essential requirements for interoperability and safety. Those shall be adhered to by the manufacturers and service providers during design, manufacturing, and installation in the infrastructural subsystems.

Consequently, each interoperability component has to be assessed for its conformity and its suitability for use. 

In case of new builds, reconstructions, or upgrades of infrastructure or rail stock, an appropriate procedure for EC verification of railway structural subsystems is required.

Conformity assessment of components and their suitability for use or EC verification of railway structural subsystems are carried out by the Notified Bodies in accordance with procedures harmonized with the requirements of the modules set forth in a certain technical specification. It is requested by the applicant (customer, manufacturer, installer, etc.) in order to prove that all requirements have been met during the design, manufacturing, and assembly/installation.

As a result, EC declaration of conformity or suitability for use or declaration of verification is issued, together with the accompanying technical file. That is one of the key prerequisites to obtain the authorization to place in service a subsystem applied for at the safety authority (Public Agency for railway transport). EC declarations are valid in all EU member states and are available to all interested parties in the ERADIS – European Railway Agency Database of Interoperability and Safety.