Modular safety case methodologies

The cost, time, and complexity of re-certifying vehicular systems through traditional monolithic safety cases are prohibitively high for optimal efficacy. An alternative approach for re-assessing and re-issuing safety cases involves breaking down the safety case into safety case modules corresponding to the modular architecture of the vehicle, updating and modifying these safety case modules with evolving design, upgrades, or the role change process.

This work presents a design methodology for the construction of modular safety cases for land vehicular systems. The methodology, SOLID, is adopted from object-oriented programming and design where it has gained acceptance as the ideal methodology to use when developing software that is likely to be flexible, manageable, and extendable over time. SOLID is a mnemonic acronym for Single responsibility, Open-closed, Liskov substitution, Interface segregation, and Dependency inversion.

Project aims

The aim of the project is to develop a methodology for the design and development of modular safety cases for land vehicular systems, which supports open and modular design, offering flexibility in configuration, upgradability, integration and rapid recertification of reconfigurable platforms.

Project findings and impact

The methodology serves as a concrete foundation for modular safety case design upon which more complicated design patterns can be built on. In addition, it provides a principle way to manage dependencies. Finally, the resultant modules and argument structure are flexible, robust and reusable. Hence, the overall safety case is easier to maintain and the cost associated with recertification is reduced.

Research findings have been included in a European standard on open system architecture. Other aspects are been discussed by stakeholders in UK/European workshops for inclusion into national and international vehicular safety standards. In addition, the results ready feeds into the on-going VRC Continuing Professional Development (CPD) course on system safety.