STPA Based Safety Analysis of Regional Data Center in CTCS-1 Train Control System

Abstract

CTCS-1 (Chinese Train Control System level 1) is applicable for the existing railway lines accounting for more than 70 percent of the total railway mileage in China, which is still under development. The purpose of this paper is to carry out safety analysis on Regional Data Center (RDC) and the core trackside equipment of CTCS-1 to identify potential hazards and generate Safety Design Demand (SDD) to provide safety guidance for system design. In view of the complicated interaction among the subsystems of CTCS-1, System-Theory Process Analysis (STPA) is adopted and applied in the system. Taking the sending of Temporary Speed Restriction (TSR) from RDC to the Onboard Equipment (OBE) as an example, the safety analysis is carried out by following the STPA process to identify the related systemic unsafe factors and the related requirements and generate SDD. Based on the SSD identified in the STPA, this paper carries out the modelling and verification for the safety critical component of CTCS-1 system via the UPPAAL model checker. The analysis results show that the STPA is suitable to discover the key factors and safety hazards of train control system and the preventive measures can be adopted to prevent the design defects and safety hazards in the early stages of system design.