On 02/11/14 14:35, Basil Jet wrote:
....
Behind the Marks and Spencers in Southgate you can see the Picc tunnel
entrances, and see how the entrance tunnel is much larger than the exit
one (the entrance is tapered to lessen the sonic boom from trains
entering the tunnel at speed.

Wow! The Piccadilly Line must have got a lot faster since I was last there.
--
Phil
Liverpool, UK