Competitive markets push manufacturers to be proactive in order to comply with more and more stringent requirements on cost, delivery schedule, service reliability, new technologies and services. This constant pressure to decrease costs and increase efficiency drives the industry to move to a product oriented approach. A foundation of a product oriented approach is a frozen technical specification including the Safety requirements. A same product can then be integrated in different train level architectures fulfilling the different market needs. Then, sub-systems having robust functional safety requirements can be easily managed at train level through the methodology presented in this paper.