CLC/TS 50701
CLC/TS 50701 is the CENELEC technical specification, published in 2021, that adapted the IEC 62443 industrial security series to railways. It defines how to apply zones, conduits, security levels and a security lifecycle to signaling, rolling stock and fixed installations. Its content has been carried forward into the international standard IEC 63452.
How it works
TS 50701 follows the structure of a railway project: it starts with a system definition and initial risk assessment, partitions the system under consideration into zones and conduits, performs a detailed risk assessment per zone, assigns target security levels and derives requirements. It then covers the security lifecycle through design, integration, acceptance, operation, maintenance and decommissioning.
The specification aligns its lifecycle with the CENELEC safety standards EN 50126, 50128 and 50129, introduces the concept of Security-Related Application Conditions handed from supplier to operator, and provides rail-specific guidance such as reference zone models and how to handle legacy systems. Being a technical specification rather than a full European Norm, it was intended as a stepping stone to a formal standard.
Why it matters for security
TS 50701 was the first document to give railway suppliers and operators a common, sector-specific language for cybersecurity, and it quickly became a requirement in European tenders and in national safety authority expectations. Many contracts and security cases still reference it explicitly.
Its successor, IEC 63452, is technically very close, so work done against TS 50701 remains largely valid. Understanding both, and how they map onto IEC 62443, is essential for anyone writing or evaluating a rail security case in Europe and increasingly beyond.
Related solution
Supporting compliance with TS 50701 / IEC 63452
Lifecycle security: understanding system behavior, identifying deviations and maintaining traceability.
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