Research On Safety Evidence Chain Traceability Method Of High Speed Railway Signal System

High-speed railway signaling is a computer-based safety critical system,to ensure its safety level faces with challenges such as 'highly systemic','complex safety features',and 'lack of objective evidence-based evaluating'.At present,safety assurance and safety assessment in Chinese railway is mainly based on Europe railway standards,and the main work is checking whether the process and submitted evidence artefacts comply with safety standards.Safety assurance and safety assessment work have to review a large number of documents.Nowadays,there is no safety evidence management tool to create safety evidence,to manage and evaluate safety artefacts.And also there is no effectively way to analyze change impact on safety evidence.In this thesis,in order to improve safety evidence artefact management in China,a new method is proposed to analysis tracing link between safety evidences and traceability of safety evidence chain in high speed railway signaling development,referring to international standards and other related researches.A model-based method to analysis safety evidence chain is also proposed,using UML Profile to establish baseline model of safety standards,regulations and code of practices.Safety evidence chain tracing model is used to assess the traceability of safety evidence chain.The main purposes of establishing safety evidence chain trace model are to guide safety assurance,conduct standard compliance check,analysis change impact and reuse safety evidence.The main contents and achievements of the thesis is as follows:(1)A tracing method of safety evidence chain is proposed,combining with the lifecycle of safety evidence and baseline model of EN50129(2)A process model of safety evidence trace is proposed,according to software requirements trace.And the tracing sceneries is analyzed,and tracing mode of safety evidence chain in different trace sceneries(3)Evaluating indicators of safety evidence chain are proposed.(4)A baseline model and a safety evidence chain trace model of high speed railway ATP product are proposed,and calculating the confidence indicators of ATP products.