ABSTRACT
Several basic and most frequently used reliability, availability, and maintainability (RAM) modeling techniques in practice for systems used in the railway industry are described in this chapter, which are useful for specification,; assessment; and possible improvement of the RAM of products and systems throughout all phases of the life cycle of a railway project. Moreover, these methods are used in the context of functional safety. For railway applications, the systematic processes for specifying the requirements for RAM and safety and demonstrating that these requirements are achieved are given in the standard EN 50126-1. Failure modes and effects analysis and failure modes, effects, and criticality analysis are preferably applied for identification of risks in early phases of the life cycle, but should be continually updated. Similarly, the bowtie method and event tree analysis help to analyze risks and controls, which should also be proactively performed. Reliability block diagrams and fault tree analysis, along with component importance measures, belong to the class of assessment techniques that are often quantitative and more useful the more information about the product or system is available. Finally, decision tree analysis supports decision making at any time a decision needs to be taken.
