CCS TSI 2023 Application Guide

Scope

ERA's non-binding guide for applying the CCS TSI (Regulation (EU) 2023/1695, as amended by Regulation (EU) 2026/693), clarifying its provisions on ETCS, RMR and ATO functionality, transition regimes, error corrections and the informative specification set. Regularly updated by the Agency, it serves suppliers, RUs, IMs, notified bodies and authorising entities implementing or assessing control-command and signalling subsystems.

ERA's CCS TSI Application Guide is the Agency's non-binding guide to applying the Technical Specification for Interoperability for Control-Command and Signalling (Regulation (EU) 2023/1695, as amended by Regulation (EU) 2026/693), clarifying how the TSI's requirements apply to ETCS, Radio Mobile Communication and Automatic Train Operation functionality. It explains the TSI's transition regimes for moving between ERTMS baselines, documents known error corrections to the underlying specifications, and describes the informative specification set that supplements the mandatory Annex A documents referenced by the TSI. As a living document, it is regularly updated by the Agency to reflect new baselines, amendments and clarifications agreed with the sector, with the current version being v3.1. Suppliers, railway undertakings, infrastructure managers, notified bodies and authorising entities implementing or assessing control-command and signalling subsystems use it alongside the TSI itself and its Annex A specifications (including the UNISIG SUBSET documents and EIRENE/FRMCS specifications) to interpret ambiguous or complex provisions consistently. It does not have legal force in its own right but reflects ERA's official interpretation of the binding TSI requirements.