From http://www.ft.com/cms/s/0/4934f824-ead3-11e1-984b-00144feab4...
> A decade later, the Jubilee line cost £36m per mile to build and its extension in the 1990s 10 times as much. The tunnels for Crossrail, the newest underground railway connection in London, are budgeted at almost £1bn per mile.
From http://www.ft.com/cms/s/0/4934f824-ead3-11e1-984b-00144feab4...
> A decade later, the Jubilee line cost £36m per mile to build and its extension in the 1990s 10 times as much. The tunnels for Crossrail, the newest underground railway connection in London, are budgeted at almost £1bn per mile.