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International Society of Science and Applied Technologies |
| Proposal and Reliability Evaluation of a Cloud-Based Railway Signalling System with k-out-of-n Logic for Ensuring Safety and Availability | ||||
| Author |
Takashi Toyama
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| Co-Author(s) |
Mamoru Ohara; Masayuki Arai; Satoshi Fukumoto
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| Abstract | Railway signalling systems require extremely high
levels of safety and reliability to prevent hazardous events such as
train collisions and derailments. Conventional signalling systems
mainly rely on fail-safe dedicated hardware architectures to
satisfy stringent safety requirements equivalent to Safety Integrity
Level 4 (SIL4). However, these architectures involve high
lifecycle and maintenance costs, leading to growing interest in the application of cloud computing technologies and Commercial Off-The-Shelf (COTS) hardware to railway signalling systems. At the same time, cloud-based systems must maintain sufficient availability even under communication disturbances such as message loss and network delays. To address these challenges, we have previously proposed a cloud-based railway signalling architecture in which replicated central units are deployed across distributed data centers and field terminals determine control outputs using k-out-of-n logic. In this paper, we reintroduce the proposed architecture and focus on improving its availability evaluation method. We clarify the limitations of existing discrete-time Markov models and propose an enhanced model considering temporary postponement of command determination caused by communication failures. Evaluation results suggest that the proposed model may provide a more realistic availability assessment than conventional models.
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| Keywords | Railway Signalling, Cloud Computing, COTS, Reliability, Safety, k-out-of-n logic | |||
| Article #: RQD2026-167 | ||||
Proceedings of 31st ISSAT International Conference on Reliability & Quality in Design |