The dependability assessment of systems and in particular their availability depends on the dysfunctional behaviors and maintenance policies of their subsystems and components. Railway systems are large due to the number of trains and routes but also complex due to the safety assured by the signalization and the interlocking. There is a need of methods and tools which could give, at the same time to people in charge of the design, operation and maintenance, the key to exploit the infrastructure at the best cost. The aim of this paper is to show how it is possible to generate automatically a model which satisfies all these requirements and how to do a performance analysis in order to get metrics in terms of capacity of the line, needs of the maintenance.