Special edition paper

signaling facilities are found between stations. They are separated by their individual functions and construct logic, mainly using relays, to send and receive conditions to and from each other (Fig. 1 (a)). This system structure is burdened by the following issues. (1) Simplex system (no back up system in case of equipment failure) (2) Huge amount of wiring work (3) Complicated relay circuit logic (4) Insufficient information obtaining about maintenance and failures from distant locations In order to solve those issues, we are proceeding with a fundamental signal system improvement project on the Chuo and other lines. In that project, we solved the issues (3) and (4) by centralizing in the signal house control devices that were distributed along the tracks (Fig. 1 (b)). But, a huge number of signal cables have to be laid from the signal house to the individual devices