The risk assessment procedure of the safety management system of the railway company must specify the methods and tools used by the railway company to evaluate the risks. The most common methods for the risk evaluation are the Failure Mode Effects and Criticality Analysis (FMECA), Fault Tree Analysis (FTA), Hazard and Operability study (HAZOP), etc.
Examples of techniques and tools for carrying out the risk assessment can be found in Annex E of Part 2 (Guide to the application of EN 50126-1 for safety) of CENELEC EN 50126 standard.
Regulation (EU) No 402/2013 presents three risk acceptance principles that are already recognised as current possible practices for controlling hazards and the associated risks in railway systems: the application of codes of practice, a comparison with similar reference systems and an explicit risk estimation.
More information can be found in the ERA guidelines.