On Sat, 16 Aug 2008 14:03:42 +0100, John Rowland wrote:

Hmm, how do you turn round a tube at Hammersmith or West Ken without
going into a tunnel?

You kick the passengers out, run non-stop empty to Green Park and then open
the doors and carry on.

Or just reverse in the (double-ended) siding between Hammersmith and
Barons Court.