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The TGV ((フランス語:Train à Grande Vitesse), high-speed train) is France's high-speed rail service. The idea of a high-speed train in France was born about twenty years before the first TGVs entered service. At that time, about 1960, a radical new concept was thought up; combining very high speeds and steep grades would allow a railway to follow the contours of existing terrain, like a gentle roller coaster. Instead of one or two percent grades which would be considered steep in normal applications, grades up to four percent would be feasible, thus allowing more flexible (and cheaper) routing of new lines. Over the next several years, this very general idea gave rise to a variety of high speed transportation concepts, which tended to move away from conventional "wheel on rail" vehicles. Indeed, the French government at the time favoured more "modern" air-cushioned or maglev trains, such as Bertin's Aérotrain; Steel wheel on rail was considered a dead-end technology. Simultaneously, SNCF (the French national railways) was trying to raise the speeds of conventional trains into the range 180 to 200 km/h (110 to 125 mph) for non-electrified sections, by using gas turbines for propulsion. Energy was reasonably cheap in those years, and gas turbines (originally designed for helicopters) were a compact and efficient way to fulfil requirements for more power. Following on the TGS prototype in 1967, SNCF introduced gas turbine propulsion with the ETG (Elément à Turbine à Gaz, or Gas Turbine Unit) turbotrains in Paris - Cherbourg service, in March 1970. The desire for higher speeds and the successful development of the turbotrain program are two ideas that came together in the late 1960s, further spurred on by the 1964 start of the Japanese Shinkansen high-speed train. They were embodied in a joint program between SNCF and industry to explore the possibility of a high speed gas turbine unit. The project, initiated in 1967, was entitled "Rail Possibilities on New Infrastructures" and was code-named C03. The experimental X4300 TGS railcar, predecessor of the ETG, had been tested at speeds up to 252 km/h (157 mph) in October 1971, and gave promising results. Since the very high speed lines envisioned by SNCF called for speeds of 250 km/h to 300 km/h (155 mph to 186 mph), SNCF had Alsthom-Atlantique build a special high speed turbotrain prototype to test out some concepts in high speed rail. Thus was born the turbotrain TGV 001, standing for Train à Grande Vitesse, or High Speed Train 001. ==The TGV 001 Turbotrain== (詳細はdynamics, braking, aerodynamics, signalling, and other technologies that needed to be developed to allow higher speeds. Only one was ever built, although it was originally planned to build a second version equipped with an active tilt system. The studies for the tilting version were completed, but it never reached construction because of technical difficulties with fitting the tilt system. The TGV 001 consisted of two power cars with three trailers in between, the whole trainset permanently coupled together. All axles were powered by electric motors, with the advantage of low axle loads and a high power-to-weight ratio. Electric traction also made possible dynamic braking, especially effective at high speeds. Each power car had a pair of turbines (the TURMO IIIG and then the TURMO X, used in Sud Aviation's Super Frelon helicopter) which ran at constant speed. They were connected to a reductor stage, whose output shaft drove an alternator. Besides the turbine drive, the power cars had control gear for the traction motors, dynamic brake grids, signalling and braking equipment, etc. 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「Development of the TGV」の詳細全文を読む スポンサード リンク
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