One of the issues to be decided in furthering the Cambridge-MK-Oxford Corridor is the final route of the Expressway between Milton Keynes and Oxford/Science Vale.
There have been two broad alternatives presented (more but it boils down to two), via Aylesbury, or to the north via Bicester. The study on this issue shows a surprisingly narrow gap between the options, especially when you consider the benefits of development facilitated, with the northern options slightly on top.
Ultimately this can’t be determined as a purely transport issue as the costs and benefits flow from where very large amounts of development go.
If forced to make a choice I think the southern option is better. It links naturally to the long grass issue of the Aylesbury Bypass, it links better to Science vale and Grenoble Road south of Oxford, and doesn’t push large amounts of traffic through Mk trying to get to the M1, and then locally along the M1 going to Bedford – the last thing you want. Finally it links to potential major development sites to the west of Oxford and around Haddenham/Thame.
However the Northern option has the benefit of linking to the potential Calvert New Town. This will require development link to expressway standard given the scale of the likely new town, even with its public transport potential.
So you can’t really determine THE route without a strategic plan for this whole area, as well as determining the link between Oxford and Swindon – as the A420 is so poor, as well as the potential for major new development in the Grove Area, where the potential for restoring four tracks between Didcot and Swindon could reolve the biggest bottleneck on the UK rail network and open up a new town as large as Calvert. Indeed Grove would be the ‘New Oxford’ in the same way Calvert could be the ‘New MK’ and Bassingbourne the ‘New Cambridge’ each Garden City preventing sprawl of the host.
Given the potential scale of the development however, especially between MK and Oxford, you can’t really talk of ‘a’ expressway route. If you develop a new town at Calvert you require an expressway, but also to serve Ayelsbury, Haddenham, Grenoble, Cheddington etc. and vice versa. So two expressway grade connections are needed, and i’m sure traffic modelling would confirm this would be much better in distributing traffic around MK and the Oxford Ring Road System and avoiding having too much strategic traffic diverting north through Calvert or conversely south around the Aylesbury ring road. Two road links should be mirrored by two rail links, not just the varsity line but the restoration of the Wycome line (already proposed on the Cowley section) via Princes Risborough to Aylesbury, and then restoration of the Aylesbury-Cheddington Link. Cheddington being a potential major node for development with HS2 freeing up capacity for local services on the four track WCML slow lanes.
Finally this approach helps solve one of the buiggest problems of the UK road network, congestion of the M1 around MK. Such a large town really needs more junctions, however local junction hopping traffic is a major problem. A new a road linking the expressway arms north and South of MK to the West of MK provide the ton with a box, and an alternative express north south link rather than the M1. This should then act as the new long term west boundary of MK.