Slovak, R.; Wegele, S.; Schnieder, E.:
Process-based safety requirements parameter derivation for a transportation system using stochastic petri nets modelling.
Proceedings of the 8th International Level Crossing Symposium - CD-ROM, Sheffield, April 2004. 8th International Level Crossing Symposium/ Sheffield 14. - 15.04.2004.
Application of universal transportation control systems designed in order to fulfil the highest
safety requirements is related with high investing, operation and maintenance costs. A solution
offers application of the new CENELEC standards for railway application, which declare the
definition of safety based on the operational risk in the transportation process. Application of
the standard recommends usage of formal methods as a support mean of design and analysis in
regard on the required legislative assessment. The paper presents an approach how to derive
the system safety requirements parameter of a railway operation control system according to
the attributes of the expected transportation process. The main tasks of safety analysis (risk
analysis, system hazard analysis) are explained, emphasizing the relation towards the
transportation process. As an example, the risk and system hazard analysis of a simplified level
crossing control system is presented. For the quantitative parameter evaluation is applied the
formal modelling using Extended Deterministic and Stochastic Petri Nets (EDSPN).