In accordance with Regulation (EU) No 402/2013, the risk acceptability of a significant change should be evaluated by using one or more of the following risk acceptance principles: the application of codes of practice, a comparison with similar reference systems, an explicit risk estimation. All principles have been used successfully in a number of railway applications, as well as in other transport modes and other industries. The ‘explicit risk estimation’ principle is frequently used for complex or innovative changes.
The proposer of the change is the one who is responsible for the choice of the principle to apply. Regulation (EU) No 402/2013 does not prescribe any order of priority between those three risk acceptance principles. However, Annex I of Regulation (EU) No 402/2013 requires the proposer to verify whether the considered code of practice or similar reference system satisfy the necessary conditions, and in particular whether it is appropriate for the control of the considered hazards of the system under assessment. This presumes that the proposer has well captured (i.e. identified), understood and analysed the specific hazards and risks related to the project.
It is to note that deviations from a code of practice or from a similar reference system must also be assessed and appropriate risk control measures put in place.
If Regulation (EU) No 402/2013 does not apply, the above approach can still be applied as it is widely recognised as good practice. A similar approach is also established in CENELEC standard EN 50126.