Shed,
Thanks for your observations and comments. As a wise man once said, you can be open to another's argument without having to accept it....
Just a couple of quick points. The scheme promoters of the various rail and road improvement projects including the Liverpool - Newcastle line will have to ascribe a value to the scheme, through a rigorous options appraisal and business case, before they go ahead. This will generate the aforementioned BCR. It will be based on information known today supported by sophisticated modelling - just as with The proposals for R3. That process will offer no more guarantee of delivering the suggested benefits than HAL's proposals do, it just helps to narrow down the options for how best to spend limited resources.
£11bn is a big figure, but needs to be taken in context. It's a little over a £1bn year over the life of the build programme, and equal to what HAL has invested since 2003. Crossrail's £14.8bn funding envelope is also a big figure when taken as one lump sum, but again that is spread over a 10 year period.
Speaking of Crossrail, I presume that you (and Bagso) have registered that the costs for Crossrail form part of TfL's magical £20bn figure, along with already committed improvements to the Piccadilly Line plus the HS2 spur and Western Rail Link? In other words it is committed money not available for spending in the regions anyway? I hadn't realised until doing some research this weekend - it is in Boris' response to the Airport Commission Interim Report in 2013...