Type DD-4 centralized traffic control system is designed for the computer aided CTC system of the test section near Tianjin. It is a system used for manual control as well as computer control.

• DD-4型调度集中系统是为天津附近行车指挥自动化系统试验区段设计的,系统既要用于计算机控制还要用于人工控制。