On Thu, 19 Jan 2006 23:25:38 +0000, John wrote:

Starting up new pits, even draining and re-starting old ones, would be
a colossally expensive business, even if we could get people to go
down there, which I doubt these days. I'm not sure even the expertise
would still be readily available in any great quantity, let alone a
workforce.

How about using robots? In the last 20 years, robot technology has
greatly improved, and industrial robots are used everywhere today.
That way, it wouldn't matter so much if a roof collapse happened, as
any trapped robots could just be abandoned, a bit like the chunnel
drilling machines.

MM