4. Conclusion

In the context of this dossier, we have presented the basic SIL allocation method as applied in the field of railway signalling.

As a general rule, the same approach is applied to other railway subsystems, but IEC/IEC 61508 is increasingly used for ancillary parts (tunnel ventilation management system, trackside announcement system, etc.).

The railway sector, through the definition of standards describing what a railway system is, aims to define a railway system as a set of products. Building a railway system could be likened to building a LEGO, but with the need to check that the products are compatible.

Acceptance of products that have already been certified is therefore a major issue, requiring the implementation of cross-acceptance analyses.