Safe Maintenance of Railways using COTS Mobile Devices: The Remote Worker Dashboard

The railway domain is regulated by rigorous safety standards to ensure that specific safety goals are met. Often, safety-critical systems rely on custom hardware-software components that are built from scratch to achieve specific functional and non-functional requirements. Instead, the (partial) usage of Commercial Off-The-Shelf (COTS) components is very attractive as it potentially allows reducing cost and time to market. Unfortunately, COTS components do not individually offer enough guarantees in terms of safety and security to be used in critical systems as they are. In such a context, RFI (Rete Ferroviaria Italiana), a major player in Europe for railway infrastructure management, aims at equipping track-side workers with COTS devices to remotely and safely interact with the existing interlocking system, drastically improving the performance of maintenance operations. This paper describes the first effort to update existing (embedded) railway systems to a more recent cyber-physical system paradigm. Our Remote Worker Dashboard (RWD) pairs the existing safe interlocking machinery alongside COTS mobile components, making cyber and physical components cooperate to provide the user with responsive, safe, and secure service. Specifically, the RWD is a SIL4 cyberphysical system to support maintenance of actuators and railways in which COTS mobile devices are safely used by track-side workers. The concept, development, implementation, verification, and validation activities to build the RWD were carried out in compliance with the applicable CENELEC standards required by certification bodies to declare compliance with specific guidelines.