OCORA — Open CCS On-Board Reference Architecture

Scope

Open reference architecture for a modular ETCS/CCS on-board system, developed by DB, SNCF, NS, ÖBB and SBB to standardise the internal structure and interfaces of on-board control-command equipment (computing platform, vehicle adapter, train display, localisation). Published as versioned open-licence releases (latest R6, 2025) with requirements, architecture models and proof-of-concept results, it is used by procuring railways and suppliers to break vendor lock-in and feeds into the Europe's Rail System Pillar.

OCORA, the Open CCS On-Board Reference Architecture, is an open reference architecture for a modular ETCS/control-command on-board system, developed jointly by five major European railway undertakings -- DB, SNCF, NS, ÖBB and SBB -- to standardise the internal structure and interfaces of on-board control-command equipment, including the computing platform, vehicle adapter, train display and localisation functions. Its aim is to break the vertical vendor lock-in typical of traditional ETCS onboard units, in which a railway undertaking is effectively tied to a single supplier for the lifetime of the equipment, by defining open, modular interfaces that let components from different suppliers be combined within a common architecture. Releases are published as versioned, openly licensed documents on the OCORA public GitHub repository, with the latest being Release R6 (deliverables uploaded February 2025), including detailed requirements, architecture models and results from proof-of-concept implementations. Procuring railways and onboard equipment suppliers use the architecture and its releases to design modular ETCS onboard systems and to structure procurements around open interfaces rather than single-vendor packages. OCORA's work feeds directly into the Europe's Rail System Pillar's future on-board architecture specifications, positioning it as an industry-led precursor to eventual formal standardisation.