Modeling and formal specification of automated train control system using Z notation

In this paper, formal methods which are advanced software engineering techniques, in term of Z notation, are applied for the specification of critical components of automated train control system. At first graph theory is used for modeling of static components of the system and then integrated with Z notation to describe its entire state space. At first real topology is transferred to model topology in graph theory and then switches, crossings, and level crossing are formalized. At the end, these components are composed to define the entire interlocking system. Formal specification of the system is described in Z notation and the model is analyzed using Z/EVES Tool.