Assuring safety in high-speed magnetically levitated (maglev) systems : the need for a system safety approach

摘要

Magnetic levitation is a railway technology that enables vehicles to be magnetically suspended above their tracks. Although this technology is still under development, magnetically levitated (maglev) systems have great potential to introduce significant changes in today's transportation networks. This thesis proposes an approach to assuring safety in high-speed maglev systems. It examines characteristic features of the systems, and analyzes the Japanese commuter railway accident in 2005, using Systems Theory Accident Modeling and Processes (STAMP) and System Dynamics models. The characteristic features reveal that the likelihood and potential severity of accidents in maglev systems are higher than those in conventional railway systems because of their high speed, levitation technology, software intensiveness, and other factors. A primary lesson learned from the accident is the importance of risk/hazard analysis that can qualitatively focus on the severity of accidents and human factors. These findings are put together in the form of requirements of risk/hazard analysis and organizational structures. This thesis demonstrates that these requirements, which are not entirely consistent with current actual practices based on international railway standards, conform well to the fundamentals of System Safety, which is an organized and established method to assure safety in complex systems.