A simplified construction model for system safety analysis and quantified risk assessment: A case study of vehicle leaved road

The fault tree analysis is a logically structured process that can help identify potential causes of system failure before the failures actually occur. However, traditional fault tree model often suffer from a lack of enough probabilistic basic events to check the consistency of the logic relationship among all events through linkage with gates. Even failures in system operation may have been experienced rarely or not at all. In order to solve the problems, this paper proposes a simplified construction model that characterizes the information flow in a system instead of simply logical relationship among all events when we carry out system analysis of accident causation or make decision for accident prevent and control. According to the definition of events, incidents, accidents and relationship among them, a simplified construction model and simulation approach have been presented in this paper through a case study of vehicle leaved road accident. The purpose of the model is twofold: first of all, the model is to capture the essential information transformations of incidents that occur in system operation, second, the model can be used as a basis for determining the various combinations of hardware, software failures and human errors that could result in the occurrence of specified undesired events at the system level. The model that developed in this paper is able to apply into the system safety analysis and quantified risk assessment for complex engineering establishments such as computer network, transportation system, especially the mechanism that lead to accident can be identified with the simulation approach.