Risk Apportionment For Railway Systems Using Constraint Programming
Free (open access)
493 - 501
M. Rafrafi & E. M. El Koursi
The apportionment of railway safety targets is a key issue in developing common safety management in the European railway system. In this paper, we develop a generic approach based on the functional railway architecture, to analyse the safety of railway systems for a unified European network and to comply with the Common Safety Targets (CSTs) required by the European railway safety directive. We suggest using constraint programmingwith the functional railway architecture, developed by the AEIF, to allocate the safety targets to the railway functions. Keywords: railway safety, common safety targets, risk apportionment, functional analysis, constraint programming. 1 Introduction The railway system is composed of various subsystems such as energy, infrastructure, control command and signalisation, rolling stock, operation, telematics, etc. These subsystems are performed by various functions, which are implemented by a number of resources and programs. These elements constitute the representative architecture  of the rail system. The interoperability of railway systems requires the clear definition of subsystems and their interaction to allow free movement of trains across Europe and to facilitate the opening of the European railway market. In order to maintain the safety level, a directive was set up by the European Commission (EC) to regulate the European railway system. European directives impose a division in the chain of the operational and safety responsibilities between the Infrastructure Manager (IM) (the person in charge of the maintenance of the rails)  and one or more Railway Undertakings (RU)  (national companies or private operators) . This shared responsibility may
railway safety, common safety targets, risk apportionment, functional analysis, constraint programming.