Division Onboard installations:

It is mandatory to fit an ETCS onboard assembly when:

• any new train protection part of a CCS onboard assembly is installed, or

• any existing train protection part of a CCS onboard assembly is upgraded, where this would change the functions, performances and/or interoperability-relevant interfaces of the existing legacy system (as referred to in annex B of this TSI). This excludes those modifications that might be deemed necessary to mitigate safety related defects in the legacy system;

It is recommended to install ETCS whenever a rolling stock already in service is upgraded when this entails an investment higher than at least ten times those associated with the installation of ETCS on that specific type of rolling stock.

After the train protection part of an onboard assembly has been upgraded, the existing Class B onboard train protection equipment may continue to remain in use, together with the Class A equipment.