Adaptive step-by-step construction technique achieving high assurance for Tokyo Metropolitan railway network

The Autonomous Decentralized Transport Operation Control System (ATOS) is a large-scale autonomous decentralized system that controls train traffic in the 17 lines in the entire Tokyo region, with a total line distance of 1,100 km, which system is being introduced by East Japan Railway Co. (JR East). ATOS and other large-scale systems need the phasing-in of a system. What is more, with changes in technology and environment, the system must be modified and developed in response to ever-changing needs of society., What is more, such a highly public system as ATOS absolutely needs to ensure reliability. To operate the ever-changing and growing ATOS with high reliability and stability, we applied assurance technology. This paper describes "adaptive step-by-step construction technique achieving high assurance" applied here, evaluates the risk of the system, and demonstrates the effectiveness of the method applied.