A lot of speculation here! But in an ideal world they'd go on Cardiff-Pompey, with everything else filtering west. As much as I love 150's, they are showing their age now, could even put them on the Cornish branches in retro liveries as "Heritage" units now lol
Lots of armchair / crayon planning in evidence here!
Diagram-wise the Cardiff-Pompey route might be relatively self-contained but it’s very short of ideal in the sense that;
- Passenger flows are not suited to end-vestibuled stock
- Multiple working ideally needs through gangways
- Several diagrams start/end Fratton, so cycling sets through St Philips Marsh is awkward. Not great for a fleet with known reliability issues!
Barnstaple/Okehampton would be doable but potentially issues with short platforms? Barny also needs 3-car units to meet peak loadings, so would depend which 175s are available. If based out of Laira this would create a lot of ECS moves as those diagrams are Exeter based and diagram cycling is designed to rotate sets through SPM, not Laira.
It might happen but I can see real operational difficulties coming along quickly if GWR do get 175s. This could turn into a ‘be careful what you wish for!’ situation with hindsight.
The problem with trying to use the 175s to replace the 150s really is what routes could a 175 do that a 150 can. I really cannot see GWR trying to clear them for Falmouth, St Ives, Looe or Gunnislake in all honestly, whereas a 150 is your go anywhere, Jack of all trades unit.
As for Cardiff - Portsmouth, while I get the point regarding depot and stabling, worrying about gangwayed stock has rather changed since the introduction of the Turbos on the route - if they can operate as a 5 car, I don’t see why the 175s shouldn’t be able to be operated that way either. End doors may be an issue, but surely the biggest area where that is a problem is the Westbury / Bath / Bristol corridor, whereas the Portsmouth end seems to cope reasonably well. That could / should be solved with Turbos working the all stations, while the 175s work the faster services.
I just feel a depot like SPM could be made to concentrate on the fleet and bring them up to scratch - they’ve lost a chunk of their work and while Laira has too, SPM has the capability to be a single point depot for the fleet whereas Laira will still have overhauls / stabling and some IET work.
