Yes cos918
I do know that A34 / M40 area quite well and can imagine what the extra traffic will do to the area.
I lived in Birmingham for some 40+ years and worked as a community Architect on several high profile projects, both regeneration of Brown field sites and new build on greenfield sites. When a new 'estate' is planned a process has to be gone through to see if the surrounding infrastructure can cope with the extra strain the new development will put on it. If it can cope, then it remains as is.. if it cant, before any development takes place, the local infrastructure has be be upgraded to a standard where it can cope.
I agree that there are probably better solutions, such as building on brown field sites within city boundaries, but unfortunatley, with the increasing population, a housing solution has to be found.. and in this case its more economically viable to build all the new houses in one place rather than dotted around the country.
When i left the housing industry, there was talk of some 100,000 houses needed in the next ten years due to the population increase... so you can expect more of these 'eco towns' springing up across the country.
Have a look at some of the recent (private venture) 'eco towns' such as Poundbury (near Dorchester)
http://www.poundbury.info/ to see the quality of such developments.