Division Track-side installations:

It is mandatory to fit an ETCS track-side assembly when:

• the train protection part of a CCS track-side assembly is a new installation (with or without a Class B track-side assembly), or

• the existing train protection part of a CCS track-side assembly is upgraded, where this would change the functions, performance and/or interoperability-relevant interfaces (air-gaps) 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 installation.

It is forbidden to upgrade Class B train-protection systems unless a modification is deemed necessary to mitigate safety-related defects in the legacy system.

It is recommended to install ETCS whenever the infrastructure or energy sub-system of a section of line already in service is to be upgraded, renewed or maintained when this entails an investment higher than at least ten times those associated with the installation of ETCS facilities on that section of line.

After the train protection part of a CCS track-side assembly has been upgraded, the existing Class B equipment may remain in use together with the Class A train protection equipment, until a date foreseen by the relevant national plan(s), and subsequently by the EU master plan, defined in clause 7.2.5. The Railway Undertaking is not allowed to oppose the removal of the Class B train-protection equipment done under such conditions.