Use-case informed task analysis for secure and usable design solutions in rail.

Meeting secure and usable design goals needs the combined effort of safety, security and human factors experts. Human factors experts rely on a combination of cognitive and hierarchical task analysis techniques to support their work. We present an approach where use-case specifications are used to support task analysis, and human failure levels help identify design challenges leading to errors or mistakes. We illustrate this approach by prototyping the role of the European Railway Traffic Management System (ERTMS) - Signaller, which provides human factors experts a chance to work in collaboration with safety and security design experts.