Hi there, the WCML sees no services to the Scottish highlands at all. You would have to change at Edinburgh or Glasgow. If LNER were to have a permanent route via Carlisle to Aberdeen once a day not only would it help with route knowledge for diversions but it would mean that the WCML would be able to have direct services to Aberdeen and York
You haven't said what route it would take, but if it's going via York then I assume you mean running across the Hadrians Wall line from Newcastle to Carlisle ... and then what, via Coatbridge?
It's absolutely bonkers.
Newcastle to Carlisle is a plain 2-track line used by 2tph stopping or semi-fast trains, plus an additional 1tph to Hexham. There is nowhere to overtake a slow train, so you would have to slot in between the existing Northern services, meaning it would take 1h10 from Newcastle to Carlisle.
Carlisle to Motherwell non-stop is 0h55 non-stop but I don't know that LNER's fleet would be able to run at full speed because they don't tilt (?) so it might take a little bit longer than that; either way, it's a busy line and could be difficult to path another train.
Motherwell to Stirling would be at least 0h35 even if you could find a suitable path.
Stirling to Dundee, a fast train can do in 0h50.
So from Newcastle to Dundee, you're looking at a minimum of 3h35 (assuming a decent path can be cobbled together), compared with the existing service via Edinburgh taking 2h50.
That time penalty will deter any through passengers for ECML stations from using it, and as it bypasses the two main cities in the central belt there is precious little reason for
anyone to use it.
Yes, it would give a direct service from "the WCML" to Dundee and Aberdeen, but only from Carlisle, which is pretty small fry by the standards of the WCML – it doesn't improve access from Manchester or Birmingham, where passengers will still have to change, so what's the advantage of changing at Carlisle over Edinburgh or York?
Or if you're talking about running out to Carlisle then back up to Edinburgh, you're doing two sides of a triangle just so that you can serve Carlisle, which already has perfectly adequate links to both Newcastle and Edinburgh where passengers can change for ECML services that are running on the ECML where they belong.