The Shinkansen automatic train control system which permits the different train control signal

East Japan Railway Company, commonly referred to as JR East, has developed a new Shinkansen Automatic Train Control (ATC) that utilizes digital communication and control. Officially named "DS-ATC," this system controls train speed mainly relying on the on-board equipment, allowing a reduction in rail-side devices. The present ATC used on the Tohoku and Joetsu Shinkansen has become outdated and needs to be replaced in several years, so its renewal plan is being drafted. JR East is planning to replace the system with the DS-ATC discussed here. Since it is difficult to replace the entire line at one time, it is necessary to divide the construction area and replace the entire line gradually. Therefore, there are places where DS-ATC and present ATC overlap, and in these places the ATC system change during high-speed service. This paper describes the mechanism of this mode change.