Quote:
Originally Posted by The Chemist
It's all overhead catenary - no third rail in Shanghai. They run at 1500VDC, so I guess third rail was thought to be too dangerous. Only issue with it is they have to build higher diameter tunnels to accommodate it.
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Nearly all metro lines in Tokyo, and many lines elsewhere in Japan, use overhead power as well. It has little to do with safety. It is done so that trains from commuter lines can be through-routed across town in the metro tunnels. This increases efficiency and cuts down on transfers. I wonder if Shanghai has any such schemes in place or planned, as that might help to explain the use of 1500vdc catenary.
For example, in Tokyo, trains on the Keisei line (a private commuter line) can enter the Toei Metro Asakusa line at Oshiage; from there trains can proceed onto the Keikyu line (another private commuter line) at Shinagawa. This allows some trains to go directly from Narita Airport all the way to Haneda Airport with no transfers.
Every line in Tokyo (except for three) has some sort of interlining with commuter lines. The three exceptions are the two oldest lines (Ginza and Marunouchi) and the Oedo line, all of which use smaller rolling stock and smaller tunnels that would be incompatible with surface lines. Incidentally, all three of these lines draw their power from 3rd rail.