Integration of functional, cognitive and quality requirements. A railways case study

The paper shows a SHEL oriented requirements engineering approach, which has been applied in a case study dealing with the definition of the requirements for a new railways traffic control system. The SHEL model provides an integrated view by considering any productive process or activity performed by a combination of Hardware, Software and Liveware resources within a specific environment. A set of SHEL oriented requirements describes the different views on a complex system. The requirements are grouped into three main classes of requirements, namely, functional, cognitive and quality requirements. The paper points out the issue of integrating different types of requirements.