Are there no longer any freight trains that use the Stockport - Navigation Road - Altrincham route? If so, I thought they had to be kept separate from any light rail services, as is the reason why the heavy rail access route into the waste compaction depot just past the former Dean Lane station will be kept separate from the new Metrolink station there and this will be similar to the current situation at Navigation Road station with parallel heavy rail and light rail single lines.
Oh... forgot about the freight segregation thing, since the plans I have would mean 18tphpt either side of nav road, it could get a tad crowded on the one platform, perhaps transfering all tram-train services North of Navigation Road, keeping all heavy and tram train services on one side, and the current tram only timetable on the other side?
Would also prevent local passengers using the Tram Train services to get into Alty/Manc from Nav Road, and if TT Services were running under National Rail rather than Metrolink, would keep that segregation quite nicely.
Would basically mean the same service levels for Metrolink at Navigation Road's 'Metrolink' Platform, and more services, ie. All Tram-Train services on the Network Rail platform, and no messing around moving from one platform t'other at Alty, handle it all at Nav Road.
Then if four tracking where put back in, keep it paired by use up to Sale, then have the junction at the 2 track pinchpoint there (Since limited stop Tram-Trains will call at Sale) and then move on from there paired by direction so that dropping to 2 track and widening to 4 track can happen more often in the form of 'slow line passing loops'
So in the end we'd have:
Alty: Network Rail 2 track through, Metrolink 2 track terminating, Tram trains on Network Rail Metals
Nav Road: Each drops to 1 track for the station, Tram Trains still on Network Rail metals (electrified at 750VOHL if available)
North of Nav Road, back out to 4 track, with the lines to Stockport diverging and 2 track of Network Rail and Metrolink lines continuing North. (Possibly single track towards sale for a short time due to restrictive former bridges)
If a single track link, this then merges into the Metrolink lines at the reversing siding south of Timperley, handing over to Metrolink infersturcture.
Doing the minimum work, Tram Trains can now run...
Basically, a little bit more pointwork between the Network Rail metals and Metrolink metals just north of Navigation Road would do it fine, would be a little bit too much single track for my liking, but if 2 track was provided between this junction and Navigation Road, and between Navigation Road and Alty, there shouldn't be too much waiting around. Especially if it then calls all stations into manchester thanks to no passing loops being added (these could always come later). 3tph then run onto Chester via Alty and 2tph onto Crewe via Middlewitch, could either be formed of the Alty - Piccadilly services, or slotted in, giving 15tph between alty and manc.