alex_t wrote:
There's also a nice picture of the MonoMetro as it passes down
Liverpool Street. But they only give 10% chance for that one, sadly.

That's really sad.
I think nobody will deny that the only unused space left in London, is
space between house *above* roads - so such project could be very
useful and really change transport situation for the better.

The sky isn't unused, it has amenity value. In America they have
progressively torn down the Els and replaced them with subways on the same
alignment.