Wednesday, November 23, 2011

Tokyo's First Linear Motor-Driven Subway

EMU Toei 12-000 series, a linear motor-driven subway train at Tochomae Station

The Toei (Tokyo Metropolitan Government) Ooedo Line is the second newest subway in Tokyo. The line was partially opened between Hikarigaoka and Nerima (3.8km) in 1991. Then, it was extended to Tochomae in 2000. Currently, the route consists of the circle section (Tochomae - Ryogoku - Tochomae, 28.6km) and the branch section (Hikarigaoka - Tochomae, 12.1km). The total operation length is 40.7km.

One of the features of this new subway line is that linear motor technology is adopted for the train driving system. A linear motor is an electric motor that doesn't have a shaft. It moves in a straight line, while a conventional motor has a rotary movement. You can see a special box,"reaction plate" between the rails (see the bottom photo). This technology allowed downsizing of the tunnel section.

The problem of the Ooedo Line is that it runs very deep under the ground, because underground utilizations in Tokyo, such as existing subways, express roads, parking and water supply systems are in an overcrowded condition. New construction is forced to go deeper and deeper. As a result, the platform of Roppongi Station is located 42.3m below the ground. Passengers have to walk down 7 flights of escalator and stairs. It takes 6 minutes including ticket purchasing time. I think it's a disincentive for potential passengers and weakens the competitiveness of the Ooedo Line.

The Oodedo Line; it was born through exploitation of the state-of-the-art technology, but is a slightly inconvenient subway line in the Tokyo metropolitan area.

Rails and reaction plate of the Toei-Ooedo Line at Tochomae Station