You would try and do what currently happens with the Northern local, you don't want to try and get it across to Nantwich.
The helpful map of Crewe station published by the Dudley mail shows where the problem is. The trains to Sandbach and beyond depart from the through platform that is platform 1.
http://www.dudleymall.co.uk/loclrail/crewe.gif
What the Dudley Mail map doesn't show is the space on the east face of the island at the North end of Platform 5. This looks as if it may previously have been home to a locomotive siding or similar. I have attached an updated map to try to show this.
The space could potentially provide an additional platform [0?] for a short train at, one would hope, reasonable cost - one new turnout plus track and buffer stop, ground clearance and modifications to railings. Going by memory this should be long enough for a Class 153 and possibly a Class 156.
The
Google Map view and
its 3D may help. to visualise this but it doesn't look how I remember it.
There is a plan to build platforms on the freight lines thus avoiding conflicting moves from Shrewsbury towards Manchester.
To correct the nomenclature, these are Crewe's
Manchester Independent lines.
I wasn't aware of a proposal to put platforms on these, but it might make sense if the Manchester/South Wales trains could be routed via the
Manchester Independent Lines and the old Platform 1 (opposite face of Platform 12). If this were done the Salop option might be on.
At the moment the
Independent Lines are painfully slow: 10mph. I travelled on them all during the 1985 Crewe remodelling and was amazed that the speeds are no more than 15mph all the way from their North end to Basford Hall Junction.