CENELEC standards EN 50126, 50128 and 50129 provide guidance on RAMS (Reliability, Availability, Maintainability and Safety) for the rail industry, in Europe and further afield, with their use mandated by some TSIs.
Since their initial publication, a number of inconsistencies (and other issues) have emerged which instigated the setting up of a CENELEC working group, TC9X/WG14, to look at revisions of the standards. In November 2012, they produced a new draft EN 50126 Parts 1, 2, 4 and 5 to replace the existing EN 50126/8/9, for formal enquiry. The new draft addressed a number of issues including alignment with the Common Safety Method on Risk Evaluation and Assessment (Regulation EC 352/2009, since replaced by EU 402/2013) and Safety Integrity Level 0 (SIL 0) functions.
That the enquiry received such a huge number of comments - over 5,600 – is partly a reflection of the differences in practice between Member States, but also the fact that EN 50126/8/9 are detailed documents specifying processes used day-in, day-out by those involved in developing safe and dependable systems.
The working group was unable to address these comments in the time left available to it, and so the revision was postponed.
A new working group, TC9X/WG21, is now working on a more limited update of EN 50126 – Parts 1 and 2 only. These will apply across the railway system. EN 50128 and EN 50129 will not now be merged into the new EN 50126.
EN 50128 on software, originally published in 2001, was revised in 2011, and rolling stock designers in particular were concerned that the 2011 version could significantly increase the cost of software for trains. It was intended that the revised EN 50126 would resolve this. Given the delay to this revision, a corrigendum was issued in February 2014 extending the deadline for switching to EN 50128:2011 to 25 April 2017. It is now planned that a revised EN 50128, meeting the needs of both signalling and rolling stock, will be published by that date.
Another working group, TC9X/WG15, is working on ‘maintenance’ of EN 50129, to cover signalling only. This is intended to align with the new EN 50126 Parts 1 and 2 being produced by WG21.
Separately, EN50155 (Electronic equipment used on rolling stock), which currently has requirements on RAMS, is to be amended to address only hardware technical requirements, leaving RAMS to the new EN 50126 Parts 1 and 2.