"The Only Living Boy in New Cross" wrote in
message m...

One of the commonest explanations you hear for
the lack of tube lines south of the river is that the
soil is unsuitable for the tunnelling equipment in
use in the early years of the 20th century. If that's
the case, though, how did the Morden end of the
Northern Line get built?

It got built at high cost, that's how. Nobody said that it was impossible.
It was the difficult and expensive experience of building the Northern Line
that deterred anyone from putting any more tubes in South London.

In any location and era, building a railway on the surface costs a certain
amount, and building it in a tunnel costs a different amount. Over the
years, land values change, and tunnelling technology improves, and safety
legislation affecting tunnelling becomes stiffer, and political opposition
to demolition changes, so there is no reason why the cheaper option couldn't
switch between overground and underground every decade or so.

--
John Rowland - Spamtrapped
Transport Plans for the London Area, updated 2001
http://www.geocities.com/Athens/Acro...69/tpftla.html
A man's vehicle is a symbol of his manhood.
That's why my vehicle's the Piccadilly Line -
It's the size of a county and it comes every two and a half minutes