The French Ferromobile project aims at proposing a tailored solution for low traffic railway passenger line, using a modified road minibus on rail tracks. Using classical trains as reference, the current paper proposes a safety strategy which uses functional specification of the existing train normative documents: Subset no26 and Subset no125. Assuming the existence of specific hazards, new safety requirements must be elicited. A methodological proposition is to enrich the existing autonomous train protection level, providing a global software framework from the specification to a formally proved Event-B model that can be used in a certified framework to produce executable code. The methodology aims at considering new Ferromobile ’s requirements using a model-based approach that generates new specific proof obligations in the Event-B model of a system graphically specified using SysML/KAOS for modelling requirements and an extension of SysML to represent High Level Architectures (HLA), called HLA/SysML. The used framework is efficient on the functional part of the system, nevertheless safety goals are more difficult to process at least due to the legislative railway safety framework. The paper concludes on the remaining challenges for a driver-less small vehicle operating on secondary railway lines.