Safety Integrity Level (SIL) Analysis by the Usage of Fuzzy Fault Tree Analysis (Case Study in Railway Industry)

The industry has been faced with the difficulty of Safety level determination for their systems. Safety is one of the most important issues in all environments. In this study, the most important thing is to determine the safety integrity level by the usage of IEC61508 standard in an uncertainty environment. At first, the concept of safety integrity level index is determined in IEC61508 standard and then the uncertainty issues are considered in the input parameters of the model. It should be noted that the uncertainty should be considered in our model because in our real environment, the processes of data gathering has uncertainty, which is clearly explained in our paper. The fault tree analysis is used to determine the fault rate of the system and the dependence of the safety system to each safety integrity level is determined more carefully by implementing the fuzzy approach. This study is implemented on train barking system as a case study and the safety level has been appointed more accuracy.