Development of Network-based Signal Control System Between Stations

nalling devices are found between stations. Each of those devices has a different structure for its individual function and they construct logic, mainly using relays, to send and receive conditions to and from each other. Fig. 1 shows the typical structure of the current sig-nalling devices between stations. In this context, the current structure has the following problems. * Simplex system (no back up system in case of equipment failure) * Complicated relay circuit logic, huge amount of wiring work * Insufficient information about maintenance and failures * Poor coordination between functions In the fundamental system improvement project of the Chuo line 1, we tried to solve the above-mentioned problems by centralizing tra-ditional field devices in a signal house and controlling signalling devices with cables. While we could centralize the logical parts, there was still the issue that we had to lay, connect and control enormou