This paper outlines the application of simulation technologies to train operation and signaling systems. It describes the background and the development of simulators in each field. It also describes difficulties encountered with conventional simulators and recent developments aimed at resolving them. The new simulator can reflect interactions between passenger behavior, train movement and the conditions of signaling systems, to obtain more precise simulation results. Finally, it presents a combined technology using the new simulator and the communication network simulator for radio-based train control systems, and its application in the future.