Abstract
In this paper, we describe a safety analysis method that utilizes two models, namely, Petri Nets to model the behavioral aspects of a system, and Fault Tree Analysis to model failure and hence unacceptable behaviors of a system. Using Petri nets and Fault Tree Analysis, we should be able to perform both forward and backward reachability analyses that are related to acceptable and unacceptable behaviors of a system. To show the feasibility of our proposed method, a case study, railroad crossing system, has been conducted.