The project inevitably polarises opinion like many other topics on this forum - well, like one other at least! - but it is important to look at the economic and social case in the round: there is more to it than just shaving minutes off the journey times between Birmingham and London.
Rail transport is one of the most sustainable forms of transport and whilst passenger usage has nearly doubled since privatisation there is still the need to encourage and attract more people to the system and create a larger modal shift than is currently occurring in order to reduce the UK's carbon footprint.
Network capacity is critical and, yes, more can be done to improve capacity on existing routes but still new lines are needed to enhance this further.
Unlike the continent, the UK doesn't have the benefit of a large structure gauge, so the ability to run double decker trains is very limited. Trains are being extend in length but even here there is still an economic implication in terms of the infrastructure alterations required to accommodate this.
Amongst other benefits, creating a new line releases capacity on the existing infrastructure for more intense use on shorter journeys and, as has been mentioned, freight.
I am sure that there will be those who say just improve what is there in order to attract more custom, particularly on overcrowded commuter routes. However to make a big difference in overall patronage it will be necessary to invest in new infrastructure too and HS2 and proposed extensions of this should be seen in this context, particularly when this can then be seen to attract current airline passengers on domestic routes.
