Where is the capacity to run 4tph and freight? Both will have to use the slow lines still
I thought the whole point of the electric spine was to divert freight away from the busy southern WCML. Genuine question, how many passenger and freight services run on the WCML per hour now?
I don't think the Electric Spine helps very much, as it doesn't serve the West Midlands, NW England or west/central Scotland which is where much of the WCML freight needs to go. Quite a few infill electrifications will be needed either to create capacity for freight on the Spine itself (Corby to Syston, Trent to Clay Cross) or to connect it to freight destinations (Leicester to Birmingham, Trent to Stoke, Sheffield to Church Fenton). Many of these benefit passengers too, but none are committed.
Capacity is maximised if all trains using the same pair of tracks have uniform average speed. This would be achieved to the greatest effect on the WCML by removing what are now the VT services and dedicating the Fast lines to trains that are probably 110mph maximum and each make a similar number of stops. The Slows would have a mix of all-stations and freight, which have similar average speeds to each other. This suggests the need for at least one flying junction, probably somewhere between Tring and Roade, where trains with few or no stops from London turn into all-stations trains (or head for Northampton) and therefore switch to the Slows.
The snag for this concept is the likes of Coventry and Stoke, which have a far better service today than they would justify on their own because they are on the way to Birmingham and Manchester. Minimising detriment to those places means retaining some 125mph EPS services, arguably at a similar frequency to today's. This eats capacity on the Fast lines because their average speed will be significantly more than that of other trains. If we have to retain today's London speed and frequency to all non-HS2 destinations then capacity release comes to three or four paths per hour: the Manchester via Crewe, the Glasgow, the Liverpool and possibly the Chester paths are no longer required.
In practice the answer will be somewhere between these extremes. I would guess that the residual Coventry and Stoke services would call at two or three stations between those places and London, which would reduce their speed differential with other services and therefore create more paths as well as directly improving service at intermediate stations. They would also have space available on board because Birmingham and Manchester passengers would be using HS2 instead, creating opportunities to provide regular all-day London services to Shrewsbury and elsewhere.
Crewe Hub, whatever that looks like, should allow trains using the high speed route to and from further north to make station calls. This should allow fairly easy connection for journeys between secondary stations north and south of Crewe.