Trackside Asset Specifications (System Pillar) — Baseline Set 4 R4

Scope

Joint EU-Rail System Pillar / EULYNX specification set standardising the interfaces and elements of trackside signalling assets (interlockings, object controllers, SCI/SDI/SMI interfaces), applicable to both the current EULYNX architecture and the future rail target architecture. Release 4 finalises Baseline Set 4 at a stable maturity level, closed to functional changes, giving infrastructure managers and signalling suppliers a stable basis for procurement and industrialisation.

The Trackside Asset Specifications, developed jointly by the Europe's Rail System Pillar and EULYNX, standardise the interfaces and functional elements of trackside signalling assets -- including interlockings, object controllers, and the SCI, SDI and SMI interface types used between them -- applicable both to the EULYNX architecture already being deployed and to the future rail target architecture the System Pillar is developing. Release 4 finalises Baseline Set 4 of the specifications at a stable maturity level that is now closed to further functional changes, giving infrastructure managers and signalling suppliers a fixed technical baseline they can rely on for procurement and industrialisation planning without the risk of the specifications changing under them. The specifications are published as freely downloadable documents directly from the project's page, without a registration requirement, making them widely accessible across the sector. Infrastructure managers use the specifications to define modular, interoperable trackside signalling procurements, while signalling suppliers use them to design products compatible with multiple infrastructure managers' networks rather than bespoke, single-customer solutions. Release 4, published 26 June 2025, is confirmed as the final release of Baseline Set 4, with no newer release announced.