"Tom Anderson" wrote in message
h.li...

I do wonder if there's room undeneath the roadway for either a huge long
road underpass, or a very shallow subsurface tram or underground line. The
Central line is presumably rather deeper, and although there will be pipes
and cables and things, dealing with these is a matter of detail
(admittedly a very expensive one) rather than a showstopper.

Although the entrances are often in the ground floor of buildings, aren't
all the underground station ticket halls immediately below the road
surface? - relocating those seems rather more than a matter of detail, I
reckon...

Paul