The question is though, what is cheaper? Demolishing ~60 houses on the Styal Branch (Some in very expensive areas) and still proberbly needing tunnelling for the through route and to complete the Delta (Unless the junction is MUCH further out, since not putting the station at Manc Airport is idiotic!) or tunneling for about 10 to 12 miles, since we'll have the TBMs already from the southern end tunnels, the inital capital costs for the TBMs is taken care of, and it would mean a much quicker alignment past Manchester.
And those saying "You can't tunnel under Manchester" I'm not mentioning any tunnels in Central Manchester, only on the outskirts. The use of the Fallowfeild Loop isn't essential, the junctioney part of the Delta can be taken care of at Longsight with three or four tunnels leaving there, and simply boring all the way to another portal at the Roaring Gate Lane area (where you can get plant in and out easilly) and Sinderland Lane...
Zero residential demolition must be something that would be a popular move.
If you want less work for the TBMs, a cut&cover box would be possible around some areas.
But if I had my ideal route, considering we already have TBMs of the correct gauge available, set up the major tunnel portals site off Roaring Gate Lane or Clay Lane to save a mile or two and have the tracks merge, possibly Roaring Gate Lane for the Manchester bound lines, and Clay Lane for the MWP (Northbound) lines, giving maximum acceleration distance for calling services. HS2 tracks off the 'Manchester South Parkway' station will dive down, lets say at Clay Lane, two will go onwards to surface at Sinderland Road in West Timperley before crossing (as previously discribed). That's 2.75mi of tunnel per track.
The route into Manchester, if you go all tunneled, comes out at Longsight then you're looking at a slightly curvey route, but the least curvey available, and about 7.5mi of tunnel per track.
You could save some tunnel by building a box immediately north of the M60 near Princess Road, having the TBM enter and exit this, and use the box to form the junction for getting to the West. Then you could either continue to run this in another tunnel, or shove it above ground, you'd have to wave around a forest, golf course and water park, but 100mph running wouldn't be too taxing. Or use the TBMs again from this box, or from Longsight, all the way out to the Carrington Junction on the M60.
At most, you'd be looking at using the TBMs for 15mi into Manchester, 10mi out of Manchester (could be as little as 0 mi but would pave over a golf course, although would provide opportunity for an additional station at Sale Water Park for the Javelin services) and 5.5 mi for the through route (the most important) to MWP.
So a fair tunneling estimation for a near perfect route (less than perfect for W from Manchester, the quality of the HS2 - HS1 Link) you're looking at about 22 - 25mi of tunnelling, and we already have the TBMs, and wouldn't need them until phase 1 is finished, but the work on the station and preparing the ground at Longsight, Manchester South Parkway, Manchester West Parkway, Fallowfeild, Sale and Manchester Baring Street can start now. Also, Manchester Baring Street, and some links into the fasts at Longsight can be completed at Phase 1, and possibly include grade seperation of Slade Lane Junction (By moving it to Longsight) and providing seperate tracks for the Styal Branch would ensure capacity on other services into Manchester.
What exactly is an LDPE service?
Long Distance Passenger Express (Intercity)
