How does the Notified Body fit in?

The Notified Body (NB) is an independent role which is similar to the independent assessor role, but the NB role belongs to the European Interoperability Directives for the TEN network and not to EN 50126. The vision of the interoperability directives is to achieve a free european market and achieve that a train, with the same train driver, can drive from Finland to Italy.

Interoperability

The concept of interoperability is defined in European Directives.
A underlaying documentation layer of Technical Specification for Interoperability, also named "TSI"'s, are affiliated to the directives.

The interoperability concept concerns all the technical functions, which must be implemented in the infrastructure and in the train fleets in order to achieve interoperability.
An example of TSI functionality is the ERTMS/ETCS system. It transmits the signal aspect of the signals into a speed mark at the speedometer of the train. Hereby, it is superfluous for the train drivers to know the signalling aspects in the country the train passes, because the train driver can rely on the mark at the speedometer.
Another example of TSI functionality is the diameter of the toilet flushing pipe. This diameter must have a certain value in order to ensure that the toilet can be emptied in any country.

A Notifed Body is an organization, which makes a Certificate of conformaty of a train or an infrastructure system against the TSI's.

The NB's are appointed by the national safety authority. There are a number of requirements to an organization before it can be appointed as a NB, e.g. it must prove it's independency, it must have the needed technical knowledge and capacity within the scope of the TSI's and it should participate in the standardization work of the Cenelec standards.

Therefore,
- the NB performs an independent assessment of the interoperability functionality against the TSI's and
- the assessor performs an independent assessment of the RAMS management against EN 50126.

It is often seen that a NB works as an independent assessor on railway projects, because they have the independency, capacity and knowledge to be an assessor.

Focus on the sources (Interoperability directives)

The European directives of Interoperability (96/48/EF, 2001/16/EF and 2004/50/EF) are parted into a directive for high-speed trains and for conventionel trains.