Division On-board installations:

It is mandatory to fit a GSM-R onboard assembly when:

• any new radio part of a CCS onboard assembly is installed (with or without a Class B system), or;

• any existing radio part of a CCS onboard assembly is upgraded, where this would change the functions, performance and/or 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.

After an upgrade of the radio part of an onboard assembly, the pre-existing Class B equipment may remain in use simultaneously with the Class A radio equipment.