This chapter follows the development process of a cyber-physical system in the railway industry. It starts from the scenario of passengers getting on and off an autonomous train and explores the engineering steps from the identification of the user needs down to the system design and implementation. The chapter emphasizes the iterative and collaborative nature of the engineering process with a special care for the continuous verification of engineering choices. Moreover, it studies how engineering data are shared across disciplines, as this is a key element supporting continuous verification.