ERA guide for application of the Common Safety Methods ... - Europa

European Railway AgencyGuide for the application of the CSM Regulation 2. DESCRIPTION OF THE RISK ASSESSMENT PROCESS2.1. General description2.1.1. The risk assessment process is the overall iterative process that comprises:(a) the system definition;(b) the risk analysis including the hazard identification;(c) the risk evaluation.The risk assessment process shall interact with the hazard management according tosection 4.1.[G 1] See also section 2.2.5.2.1.2. The system definition should address at least the following issues:(a) system objective, e.g. intended purpose;(b) system functions and elements, where relevant (including e.g. human, technicaland operational elements);(c) system boundary including other interacting systems;(d) physical (i.e. interacting systems) and functional (i.e. functional input and output)interfaces;(e) system environment (e.g. energy and thermal flow, shocks, vibrations,electromagnetic interference, operational use);(f) existing safety measures and, after iterations, definition of the safety requirementsidentified by the risk assessment process;(g) assumptions which shall determine the limits for the risk assessment.[G 1] This article lists the minimum requirements to be addressed by the system definition. Theassumptions that set out the limits for the system need to be exhaustively listed (see point(g)). These are registered in the hazard record in the same way as the safety requirementsthat are set out in the risk assessment. As the system assumptions determine the limits andthe validity of the risk assessment, the risk assessment is updated or replaced by a new oneif these assumptions are changed or revised.[G 2] In order to enable the risk assessment to be done, the definition of the system needs also totake into account the context of the intended change:(a) if the intended change is a modification of an existing system, the system definitionneeds to describe both the system before the change and also the intended change:(b) if the intended change is the construction of a new system, the description is limited tothe definition of the system as there is no description of any existing system.[G 3] The system definition is an important step in the risk assessment process. Initially, itspecifies the system purpose, functions, interfaces and all the already existing safetymeasures inherent to the system. During the different iterations of the risk management andrisk assessment processes, it is reviewed and updated with the additional safetyrequirements identified by the risk analyses. Reference: ERA/GUI/01-2008/SAF Version: 1.1 Page 32 of 54File Name: Guide_for_Application_of_CSM_V1.1.docEuropean Railway Agency ● Boulevard Harpignies, 160 ● BP 20392 ● F-59307 Valenciennes Cedex ● France ● Tel. +33 (0)3 27 09 65 00 ● Fax +33 (0)3 27 33 40 65 ● http://www.era.europa.eu