Agile Practices in Regulated Railway Software Development

Complex software is becoming an important component of modern safety-critical systems. To assure the correct function of such software, the development processes are heavily regulated by international standards, often making the process very rigid, unable to accommodate changes, causing late integration and increasing the cost of development. Agile methods have been introduced to address these issues in several software domains, but their use in safety-critical applications remains to be investigated. This paper provides an initial analysis of agile practices in the context of software development for the European railway sector, regulated by the EN 50128 standard. The study complements previous studies on the use of agile methods in other regulated domains. A systematic mapping between EN 50128 requirements and agile practices showed that all practices support some objectives of the standard. Important supporting features recognized were focus on simple design, test automation, coding standards, continuous integration and validation. However, several problematic areas were also identified, including vague requirement analysis and change management. Most agile practices must be adapted to suit regulated software development and this analysis outlines a subset of the required changes.