Software safety and dependability for railway control systems

The requirements of the Common Safety Method (CSM) [7], introduced as a result of the European Commission Railway Safety Directive [6], place mandatory requirements on the proposer of significant changes to rolling stock or infrastructure to adopt engineering safety management principles and to assess risk and implement risk controls. The increasing use of programmable systems for railway control systems presents challenges for suppliers in controlling the risks presented by errors within the software. Software has characteristics that set it apart from other engineered products. This paper explores how contemporary software development methods and techniques can be employed during the design and testing of software to provide high levels of confidence in the integrity of the final product and to show that the risks encountered by software failure have been controlled.