On Tue, 24 Jun 2003 [EMAIL PROTECTED] wrote:
> Yes. IIRC, the cost for the four BART stations that opened this Sunday
> was $1.5B. OK, the stations are extra cost (and I don't know if right-of-
> way purchase is included) -- but that's for the run from Daly City to SFO --
> a fairly short distance. And that's above ground.
As I understand it, above ground (or almost above ground) in many ways is
the *worst* case. It's the right of way, and assorted complications like
interactions with existing structures, pipelines, etc., that really run up
the cost. Deep tunneling through reasonably solid rock is actually quite
cheap -- not trivial, and not fast, but not particularly costly.
> Probably the closest we could get would be to multiply the total cost of
> the Chunnel (was it 22 miles long?) by the factor needed to make it span
> the USA.
Hard to say how representative that would be. I gather they had a fair
bit of trouble with water, which would be only a localized problem. But
they otherwise had extremely favorable tunneling conditions -- one reason
why the Channel Tunnel had been thought attractive for so long was that
there's a layer of chalk at the right depth, strong enough to be
self-supporting but much easier to excavate than hard rock.
> And, despite the transatlantic tunnel study I saw on the Discovery
> Channel's _Extreme Engineering_ recently, I worry about the effect of
> earthquakes.
Special precautions would be needed when crossing faults, for sure. (How
on Earth did they propose to run a tunnel through the Mid-Atlantic Ridge???
I suppose you might be able to sneak over it on the surface by going via
Iceland...)
This is all getting pretty far afield from rocketry! :-)
Henry Spencer
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