Reaching the critical software safety requirements is one of the most important and complex tasks for the safety-related industry. This fact explains, as it was highly recommended by the CENELEC standard, the increasing use of formal means in the development process. However, industrial environments are still reticent facing difficulties in incorporating those formal methods in a larger scale of application, especially because of their mathematical modeling complexity. The present paper proposes a Petri Nets-based approach for safety critical software development using a formal transformation into B abstract machines. This work presents formal definitions for the translation of Colored Petri Nets to B abstract machines. As part of the French research project called 'PERFECT', it aims at enabling a stronger combination of formal design techniques and analysis tools in order to cope with the real complexity of critical software development and to prove in an automated manner that the final software product satisfies all safety requirements. Therefore, the use of the B method will broaden the scope of its applicability by providing a new input modeling alternative. An illustrative application of the transformation practical use is shown in this paper for a railway level-crossing case study.