Reference CCS architecture

Reference CCS architecture

When considering the business challenges facing the railways and recognising the opportunities provided by a collaborative approach to Command and Control Systems (CCS), Infrastructure Managers consider that a joint development of a future 'Reference CCS Architecture' (RCA) will have many benefits. A White Paper has therefore been developed to express the thoughts of the members of the ERTMS Users Group and the EULYNX Consortium.

The RCA White Paper and related communication strategy are aimed at:

  • Highlighting the opportunities associated with Infrastructure Managers working together to develop a single modular framework for future CCS where the interfaces that are being developed within EULYNX are a vital cornerstone;
  • Providing a common understanding for Infrastructure Managers, industry partners and other stakeholders on the RCA initiative;
  • Providing the background and justification for the RCA initiative;
  • Providing direction to industry partners and other stakeholders, including recognition of the benefits associated with building upon and aligning existing developments such as ETCS, ETCS Game Changers, EULYNX and Shift2Rail;
  • Providing assurance that the RCA initiative will respect existing CCS investments by recognising the need for a flexible migration approach;
  • The White Paper also highlights how the Infrastructure Managers will organise their collaborative approach, utilizing the existing ERTMS Users Group and EULYNX Consortium to provide the technical direction and development activities. It also identifies the need for engagement with Railway Undertakings and Suppliers.

Based on the white paper, the RCA initiative is driven by several railways organized in EUG and EULYNX. The RCA initiative strives for a substantial improvement in cost, capacity, safety, reliability of the CCS (command, control, signalling) system. RCA starts with radio-based ETCS cab-signalling and EULYNX interfaces and adds a harmonized architecture with clearly defined interfaces leading to an upgradable system with interchangeable components. RCA includes the game-changers such as  ATO, moving block, train-borne localization, FRMCS.

RCA Gamma release

After the Alpha and Beta releases in 2019, we are happy to announce the next update of RCA. RCA Gamma is an update taking into account feedback from railways, suppliers and sector organizations. RCA Gamma provides new topics and reorganizes the existing material to be able to move to model-based specifications.
New topics include: Migration with RCA, Principles of the Safety Logic, Business case of RCA for IMs, LSL (Enhanced L3, Supervision, Localisation) and many others (for more detail, check the Release Notes). The first “development snapshots” of the model-based specifications will be made available starting March 2020.

The complete set of RCA Gamma documents is available for download via the link on this page.

If you would like to give feedback or to become involved in the evolution of RCA, please contact us.

Joint statement RCA - UESC

The Reference CCS Architecture (RCA) Strategy Group, representing ERTMS Users Group and EULYNX, and the UNIFE ERTMS  Steering Committee shared their views about the issues which need to be addressed in the context of a future Control Command Signalling (CCS) Framework. A statement has been prepared which  summarizes the view shared by these two Parties, as well as elements where they must deepen their joint understanding. This joint statement is available for download on this page.


The focus of RCA is on the architecture of the CCS trackside. There is a similar initiative, called OCORA, which addresses architecture of the CCS on-board side. Please follow the link on this page for more information on OCORA.

RCA supports the new Shift2Rail project LinX4Rail

Within the Shift2Rail programme the LinX4Rail projects was set up to develop and promote a sectorial common Functional Railway System Architecture. This activity will be supported by a widely adopted Shift2Rail Conceptual Data Model (CDM).
The ambition of LinX4Rail is to achieve an overall system architecture for the railway system and a strategy for implementation of future technical breakthroughs.  

RCA supports this idea and contributes by an active exchange and collaboration. RCA brings in its achievements for the CCS architecture, which is expected to be the core of the Functional Railway System Architecture.

For more information on LinX4Rail, see the link on this page.