Title Enhanced integrity testing of train order computer systems
Author Anderson, K
Lambert, M
Conference CORE 2000, Railway Technology for the 21st Century, Conference on Railway Engineering, Glenelg, South Australia, May 21-23, 2000
Publication Date 2000
Location Server
ARRB library
Abstract This paper describes the enhanced integrity testing of Train Order Computer Systems {TO CS) by applying the international safety critical software standard, IEC61508, to railway Train Order Working (TOW) operations in New South Wales and Victoria. This process is used to ensure that the TOCS is complete, consistent, and correct as well as to ensure that the Safety Integrity Level (SIL) requirement of the supporting GPS Watchdog is fulfilled. The paper is presented in six sections. The first section covers the background and describes the risk-based approach, the background model as presented during Core 95 and an update for Core 2000. Sections 2 & 3 describe the overall system definitions and the concept understanding. These include the activities and the procedures involved, the application of IEC 61508, the role of the Functional Safety Assessor and the concept of risk timelines. The overall system definitions include the physical equipment and the procedures involved in the Train Location sub-system, the Train Control sub-system; the Communication Sub-system and the Train Driver Safety sub-system. Section 4 describes the hazard and risk analysis. This includes the updated model detailing the sequence of events leading to hazards as well as the consequence and frequency of events and a discussion of relevant human factor issues. Section 5 describes the overall safety requirements of the system. This includes the use of enhanced integrity testing, the process of proving the system is complete, consistent and correct. This section also discusses the peer review of the Safety Integrity Level of the GPS Watchdog, the tolerability of the risk from each hazard and suitable risk criteria. Section 6 discusses the next steps. This includes the future of enforcement, in cab communication and location systems or enhancements to the basic Train Order System.
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CORE 2000_Anderson
Subjects Standards
Safety
Intelligent transport systems (ITS)
Communications
Risk analysis