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The Sendai Subway Namboku Line (仙台市地下鉄南北線, Sendai shi chikatetsu nanbokusen) is a rapid transit line of Sendai Subway in Sendai, Japan. It connects Izumi-Chūō Station in Izumi-ku, Sendai, with Tomizawa Station in Taihaku-ku, Sendai. The line is 14.8 km (9.2 mi) long and has 17 stations. Like many mainline trains and metros in Japan, it uses the 1067 mm track gauge and runs on 1,500 V overhead line. The name "Namboku" means south–north, which is the general direction that the track runs.
The Namboku Line was the world's first public railway to use fuzzy logic to control its speed. This system (developed by Hitachi) accounts for the relative smoothness of the starts and stops when compared to other trains, and is 10% more energy efficient than human-controlled acceleration.