This paper presents a specification of the hybrid ERTMS/ ETCS level 3 standard in the framework of the case study proposed for the 6th edition of the ABZ conference. The specification is based on the method and tools, developed in the ANR FORMOSE project, for the modeling and formal verification of critical and complex system requirements. The requirements are specified with SysML/KAOS goal diagrams and are automatically translated into B System specifications, in order to obtain the architecture of the formal specification. Domain properties are specified by ontologies with the SysML/KAOS domain modeling language, based on OWL and PLIB. Their automatic translation completes the structural part of the formal specification. The only part of the specification, which must be manually completed, is the body of events. The construction is incremental, based on the refinement mechanisms existing within the involved methods. The formal specification of the case study is composed of seven refinement levels and all the proofs have been discharged with the Rodin prover