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The Nanakuma Subway Line in Fukuoka, Japan, which opened in February 2005, is a linear-motor subway developed by Hitachi, Ltd. Compact, good at handling curves and steep grades-and garnering attention as the regional mass transit system of the future.
A linear-motor subway is driven by a linear motor where magnetic energy is generated between magnets in the train and plates in the track. This allows the chassis of the cars to be lower than conventional subway cars, and a more compact design, in turn, allows the diameter of tunnels to be reduced by almost half.
Another feature of a linear-motor subway is to allow exceptionally tight curves because of the magnetic propulsion system and to enable the rails to be laid beneath existing roadways and intersections-reducing the constraints on new routes.
These characteristics of a linear-motor subway reduce the environmental impact: smaller-diameter tunnels are less costly to build and there is less excavated dirt and rocks.
Comparison of Linear-Motor and Conventional Subways
Fukuoka City Subway's Nanakuma Line has a number of innovations in addition to linear-motor propulsion, focused on the goal of passengerfriendly regional public transportation. For developing the cars, the priorities were noise reduction, roomy interiors, and Universal Design. Input from a design committee, made up of the Fukuoka City Transportation Bureau, local residents and experts, was closely evaluated.
Reduced tunnel diameters can also mean increased noise, but this was minimized by soundproofed wheels, antivibration materials, and double-glazed windows. To produce a sense of spaciousness, and to make the best use of limited interior space, under-seat lighting and other elements were used.
Other aspects of overall system and station design include the operations control system designed by Hitachi for greater safety and reliability, elevators for easy wheelchair access, and less gap between trains and platforms. Aboveground entrances were also given an innovative design, reflecting the local cityscape.
The new line has become a convenient transportation system for local residents, linking residential areas with the city center and alleviating traffic congestion within the city.
In recognition of these achievements, at the 35th Machine Industry Design Awards in 2005 (sponsored by Nikkan Kogyo Shimbun), Hitachi shared the Minister of Economy, Trade and Industry Award with the Fukuoka City Transportation Bureau and also won the Laurel Prize given by the Japan Railfan Club.
Hitachi will continue to provide comprehensive solutions for people-friendly regional public transportation, from design and construction of the trains to the systems used to monitor and control them.
(Published in July 2007)