This paper presents an overview of why Model Based System Engineering (MBSE) is the mandatory solution to engineer complex railway systems and subsystems, giving some insights about the complexity and technical challenges. But its main focus will be on how MBSE can be a key enabler on the implementation of an extend enterprise approach in the engineering domain. The case study would be on a rolling stock systems and brake subsystems developed by two companies respectively Bombardier Transportation and Knorr Bremse which are dealing into the customer-supplier relationship.