Application of Functional Resonance Analysis Method to Evaluate Risks in Train Maneuvering

In this study, a novel method of safety analysis for safety management in train maneuvering is proposed based upon a systemic accident model, in which a train maneuvering activity by a train driver is regarded as a system of interrelated functions to be attained. Our method is based upon an original idea of Functional Resonance Analysis Method (FRAM) that was proposed by Hollnagel (2004), and our proposal attempts to identify how an unsafe event did happen as a result of interactions of deviated functions. For this purpose, at first a representation scheme for structuring interrelationships among train drivers' task components is provided. These interrelationships are derived from sources of drivers' instruction manuals, rules, regulations, etc. and are represented as interrelated networks of functions. Then, for a particular unsafe event that was actually happened in the past, our scheme is applied to represent the underlying maneuvering task and it is shown how the normal task procedures turned out to be an unsafe event through the propagations of primitive and local deviations towards the other part of the task. In this way, our method can replay a scenario of how the unsafe event did happen, and in addition to that, is able to detect latent hazards that did not actually happen but might happen when some conditions underlying at the event were to change from the original case.