Frankly I think the Cumbrian services should be abolished and replaced with shuttles from Lancaster and Oxenholme respectively until such time as they are electrified. They cause ludicrous amounts of diesel under the wires.
There would be a reasonable case to cut them back to Preston, which would allow connections with the half-hourly high-capacity Blackpool service. Unless timings were done very carefully, cutting them back to Lancaster and Oxenholme would potentially cause considerably increased journey times.
Still gets them off Castlefield, of course.
I guess it depends on what else runs the Manchester-bound paths, if anything.
For example, if you had a half hourly Manchester Airport - Castlefield - Bolton - Preston - Lancaster EMU (with bi-hourly extensions to both Edinburgh and Glasgow) then you'd have plenty of connections at Oxenholme/ Lancaster, without the need to run DMUs under the wires from Lancaster to Preston. An EMU could be expected to provide a lot more seats than a single 195.
If the plan is to cap the Barrow/ Windermere services way short of Manchester
without running a replacement from Lancaster/ Preston to Manchester then I guess Preston would be more attractive. However you've also got the opportunity of interworking Barrow/ Windermere services at Lancaster with services to Morecambe/ Skipton.
I wonder ...
Looking back to the start of this thread, just a week and 450 postings ago, would it help to see a 'London Tube' like map of Manchester? Would that give some idea about what goes from where to where and where to change for this or that?
For me the difficulty of producing such a clear 'visual' (let alone a clear vision!) illustrates the issue. How can a visitor be expected to navigate their way?
OK- the 'immediate' task is to 'solve' Castlefield with the existing infrastructure. That must be the focus. K.I.S.S.
If you are looking for a map of the (pre-Covid) status quo, I'd recommend this site >>
https://alexhancock.webs.com/Great Britain Train Services - Dec 2019.pdf
You can see the mess of services around Manchester, the different combinations of hourly service that cause all of the problems (each line on the map is an hourly service - some corridors don't seem to have *lots* of trains per hour, but the problem is the awkward mixture of where services start/end - e.g. the Hadfield and Rose Hill Marple lines don't have many problems, they are pretty self contained - but the Castlefield corridor squeezes trains from all over northern England (Newcastle, Barrow, Liverpool etc) and further afield (Nottingham, Llandudno, Glasgow etc)
Could work, but taking Windermere down to 1tp2h would be both unpopular and utterly pointless. An Oxenholme shuttle would have to do the alternate hours.
My understanding is that a Lancaster - Barrow - Lancaster diagram would take about as long as a Lancaster - Oxenholme - Windermere - Oxenholme - Windermere - Oxenholme - Lancaster service - i.e. a bi-hourly service from Lancaster would have enough time to do a double run on the Windermere branch and be back at Lancaster in the same time as a train could get to/from Barrow. I may be wrong though.
Preston-Blackburn could use 3tph
Preston - Blackburn seems like a really neglected pair of places - there's a decent enough bus service between them but the trains have never been more than two per hour since I can remember (and one of those was generally a 142 until very recently) - feels like it could justify an extra train or two - but these are the kind of unglamorous pairs of places that don't get as much attention as the likes of Windermere