In model driven engineering, model transformation is the 'heart and soul'. The purpose of using a model transformation is to save efforts and reduce errors by automatically building the models that conform to different modelling languages. In the French railway industry, the Petri nets and the B Method are two recognized formal methods for safety critical systems, having their own successful applications. The Petri nets are a mathematical modelling language for describing the distributed systems, and they offer superior graphical notations for stepwise processes. The B method is a software development method based on abstract machine notations and the concept of refinement. There are already some tools supporting B language. The Petri nets are accepted by the French railway specialists, because they have user-friendly notations. Consequently, various railway systems and key components have been specified by Petri nets and have been validated by railway experts. For a better model representation, the 'prioritized transitions' can be a useful mechanism in such models. In order to produce the final executable codes and to make use of all the existing valid models, this paper introduces a transformation method, which could take advantage of both formal languages and transform a valid Petri net model to an abstract B machine. This transformation is presented with a systematic mapping process and illustrated by a case study.