| dc.description.abstract | In Japan, the Tokaido Shinkansen, a major high-speed rail corridor, plans to introduce Grade of Automation 2 (GoA2) through Semi-Automatic Train Operation (STO). While partial automation promises advantages such as reduced driver’s workload and enhanced efficiency, it also creates new risks due to increasingly complex interactions among automated control systems, human operators, and physical infrastructure.
This thesis aims to systematically identify and address potential hazards arising from STO in high-speed rail. By using the Tokaido Shinkansen’s announced plan as a model case, the research seeks to uncover scenarios in which normal, non-failed system behaviors can still lead to unsafe outcomes, and to propose design solutions that mitigate those risks early in development. To achieve this, the study applies Systems-Theoretic Process Analysis (STPA). Rather than isolating hardware and function failures, STPA models the entire system as a hierarchical control structure, examining each controller’s possible unsafe actions and their feedback pathways.
The analysis reveals hazard scenarios that traditional failure-based methods might overlook. Examples include cases where a passenger is not detected between the train and platform doors at departure, or where verbal and signal instructions conflict and delay the driver’s response. These scenarios can happen even without any component failure. Drawing on these insights, the thesis recommends a variety of design improvements, such as new monitoring functions for subsystems, modifying instruction interfaces, and strengthening the software logic of automation systems.
These findings demonstrate the value of conducting a holistic safety analysis using STPA at the conceptual design stage, before late-stage changes become more expensive. Moreover, this research provides a comprehensive, system-level railway hazard analysis, and the proposed measures can be broadly applicable to high-speed rail systems with automation. | |
