On Wed, 14 Mar 2012 18:27:42 +0000, Mizter T
wrote:

The contract is only for ticket offices, escalators and platforms
because it would have required major construction work to have added
connectivity to the network's tunnels.

A pity they seem to have ruled out connectivity within the
tunnels/trains themselves. Subway systems in other parts of the world
have been able to achieve this, apparently without too much
difficulty.

Chris