Tom Anderson wrote:
wouldn't it have made sense to build the underground to be
compatible with the rest of the network, as, AIUI, in Tokyo?

Digressing a bit, I've always wondered why the South coast of England
(mainly the South East) uses the 700V DC "third rail" system for electrical
power, when the entire rest of the UK uses the 25000V AC overhead cable
system. Wouldn't it make more sense to have the same used all over the UK?
It means that a lot of national-running trains have to be diesel.

--
"We are now approaching Paisley Gilmour Street"