Ignoring all other factors, your pricing ($2,000/meter) is probably relatively close based on my personal experience. Normal soft rock tunneling can cost as little as $100/meter (at ~5m/hour) but given some of your parameters, the costs would almost certainly skyrocket based on the dimensions and extreme length of this tunnel. Hard rock tunneling will cost a little more (rates are often based on time, not distance) since it will take longer to drill through. I would love to know how you expect to change drill heads twice a day when the drill is several thousand kilometers away in a tunnel under the ocean.
However, the concept is (more or less) an engineering impossibility for a number of reasons. Question: Why don't you just lay the optic fiber across the ocean bed like everyone else?
At 02:39 PM 11/12/98 +1000, you wrote:
> Methinks I have a crazy plan!
> How about this; an underground tunnel, approx 1m across, which
>would run from Melbourne, in Oz, under the seabed to California, housing
>optical fibre cables.
> The distance is about 12000km give or take.
> I guesstimated that tunnelling and optical fibre costs would be
>around US$2000 per metre. So that figures to be US$24G.
> I would be interested in any comments on the validity or costings
>of such a scheme.
>(I reckon' it could be part of a global neural net of super fast data links.)