Control systems have been put into practical use in all the fields of the industrial world. In a conventional system, a central system controls devices directly. This is called a central control system. However, this system configuration has a limitation to meet variety of needs and situations that change from hour to hour. Therefore, autonomous decentralized techniques have come to utilization and have been put into practical use in various fields. Factory automation, public facility management, building facility management, steel production management, power equipment management, etc. are the examples. Train control systems have also been utilizing autonomous decentralized techniques. As a result, these systems have contributed to improve not only safety but also service, such as transport capacity increases and ride comfort improvement. In this chapter, the background of realization of these systems, transition of technology, and assurance techniques are described.