Safety critical systems require justifications that they are acceptably safe to operate in their defined operational contexts. Such justifications are obtained through the engineering process typically referred to as Safety Critical Systems Engineering (SCSE). Amongst all engineering artefact produced throughout SCSE, Assurance Cases play an important role. An assurance case typically organises and pulls together information regarding system safety from engineering artefacts in an structured argument, which allows stakeholders to communicate and assess the confidence of system safety.

Assurance cases have been manually created documents, which are often evaluated through lengthy and complicated processes. With the increasing complexity of systems, managing their development life-cycles in SCSE becomes a significant challenge. Furthermore, as Robotics and Autonomous Systems (RAS) are being increasingly adopted, there is a growing need for dynamic assurance cases to support runtime assurance case evaluation, enabling continuous assurance in changing and uncertain environments.

In this paper, we present ACCESS - Assurance Case Centric Engineering of Safety–critical Systems, an innovative engineering methodology that is driven by model based assurance cases, to improve the efficiency and quality of system assurance activities, supporting the development of safety–critical systems around evolving model-based assurance cases and enabling automated evaluation both during development and runtime.

We also present our tool support for ACCESS, the Assurance Case Management Environment (ACME), that supports the creation, management, and automated evaluation of assurance cases, with support for automated traceability management to engineering artefacts that are external to assurance cases (e.g. system architectural models, safety analyses, and system behavior models).

We also provide a detailed case study on an Autonomous Underwater Vehicle (AUV) to illustrate how ACCESS should be followed, with the support from ACME. In addition, we perform a systematic evaluation and report on efficiency, generality, coverage and scalability of our approach and tool, which shows promising results.

By automating key aspects of assurance case management and evaluation, ACCESS significantly improves the efficiency in SCSE and enhances the safety of safety critical systems. This robust framework for continuous assurance in dynamic environments represents a substantial advancement in safety–critical systems engineering, particularly in the context of increasingly autonomous and interconnected systems.