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The New York Metropolitan Transportation Authority (MTA) operates the New York City Subway, which is mostly manually operated. The subway system currently uses Automatic Block Signaling with fixed wayside signals and automatic train stops. Many portions of the signaling system were installed between the 1930s and 1960s. Because of the age of the subway system, some replacement parts must be custom built for the MTA, as they are otherwise unavailable from signaling suppliers. Additionally, some subway services have reached their train capacity limits and cannot operate extra trains with the current Automatic Block Signaling system. The MTA has plans to upgrade the entire New York City Subway system with communication-based train control (CBTC) technology, which will control the speed and starting and stopping of subway trains. The CBTC system is mostly automated and uses a moving signaling system – which reduces headways between trains, increases train frequencies and capacities, and relays the trains' positions to a control room – rather than a fixed position signaling system. This will require new rolling stock to be built for the subway system, as only newer trains can use CBTC systems. ==Extant signaling system== The New York City Subway system has, for the most part, used block signalling since its 1904 opening. , the system consists of about 14,850 signal blocks, 3,538 mainline switches, 183 major track junctions, 10,104 automatic train stops, and 339,191 signal relays.〔 The New York City Subway generally distinguishes its current signals into: * automatic signals, controlled only by train movements * approach signals, like automatic signals, can be forced to switch to stop aspect by interlocking tower * home signals, route set by interlocking tower * additional signals (call-on, dwarf, marker, sign, time signals) Common automatic and approach signals consist of one signal head showing one of the following signal aspects: * stop (one red light); with special rules for call-on and timer signals * clear, next signal at clear or caution (one green light) * proceed with caution, be prepared to stop at next signal (one yellow light) Where different directions are possible, the subway uses both speed and route signalling: * upper signal head for speeds * lower signal head for routes (with main route shown green and diverging route shown yellow) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Automation of the New York City Subway」の詳細全文を読む スポンサード リンク
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