CENELEC EN 50126 / 50128 / 50129
EN 50126, EN 50128 and EN 50129 are the European railway RAMS standards. EN 50126 defines the reliability, availability, maintainability and safety lifecycle; EN 50128 covers software for railway control and protection systems (Safety Integrity Levels); EN 50129 covers safety-related electronic signaling systems.
How it works
EN 50126 establishes the system lifecycle and the process for specifying and demonstrating RAMS requirements. EN 50129 applies it to safety-related electronic systems for signaling, defining the safety case structure and hardware requirements for each Safety Integrity Level (SIL 0 to 4). EN 50128 defines the software development process, techniques and independence requirements for each SIL.
Together they form the basis on which signaling systems in Europe and many other regions are certified as safe.
Why it matters for security
Safety certification under these standards makes rail systems slow to change: a patch or configuration change to a SIL 4 interlocking may require re-assessment. Cybersecurity controls for such systems must therefore be non-intrusive and must not alter certified behavior, which is why passive monitoring and compensating controls are preferred in rail OT.
Related solution
Supporting compliance with TS 50701 / IEC 63452
Security that respects safety certification: non-intrusive monitoring of SIL-rated systems.
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