Thanks for everyone's answers so far, by the way.

On Wed, 26 May 2004, John Rowland wrote:

"Richard J." wrote in message
...
Tom Anderson wrote:

I can see why it might be greater - there's more mass to shift, more
surface to line - but not massively greater.

I think that nowadays these seem to be a relatively small part of the cost
of building a railway.

Precisely!

I suppose the meta-answer is that when the tubes were built, through
running wasn't on the radar, so there was no point in building them
bigger. However, i do suspect that - where the constraints of the geology
and other subterranean structures permit - new lines ought to be built to
mainline gauge; the relative marginal cost is small, i think, and the
options it gives us for the future are large.

Further to one of Mark Brader's points, when Crossrail 2 (aka Chelsea
Hackney) was planned to be tube gauge it was planned to have a station
at Piccadilly Circus. When the plan changed to mainline gauge, this
station was deleted from the plan because there is not enough room in
that area for the larger platform tunnels that a mainline gauge line
would need.

Constraints like this. Yes, i think the lure of a station at Piccadilly
Circus would be enough to convert me to tube gauge here!

tom

--
drank lots of pints of beer, usually grolsch/met friends/museums/watch tele/read papers/thought a lot/walked much/much tube (no accidents)/some burgers/some pizza/some resturants (the ones I could afford)/some english breakfasts/some puddings -- Dor Zaf, 15 days in the UK