Network Rail are to lengthen platforms at Slaithwaite and Marsden to be able to take trains up to 96m in length - that would cover a pair of 170s pre-electrification and a 333 post-electrification or obviously shorter trains like a 185 or a 319.
I know that it's planned to extend Marsden and Slaithwaite (Slawit), but when it's going to happen is another matter- We need it NOW! Several of the current stoppers are 4/6-car West of Standedge, but the rear one or two units has to be locked out at Greenfield.
Well, Marsden p3 won't take much extending...just fell a tree and plonk it on one end...that's how the current platform is built
Quite a few of the 1980s/early 1990s WYPTE-sponsored reopenings used that rudimentary timber platform type (Slawit; Deighton; Berry Brow; Outwood; and both Marsden & Mirfield's third platforms) which presumably kept costs down... though I wouldn't be surprised if any extensions now have to be a bit more substantial- just hope it doesn't require the whole structure to be replaced as that will push the costs through the roof!
No Network Rail specified the length and I have a diesel and an electric example of formations that length.
With Network Rail having no idea what EMUs would be used on North TPE they have assumed the acceleration and top speed of the units used on express services to York/Newcastle would be similar to (if not better than) a class 380 while for electric semi-fasts and Huddersfield-Leeds stoppers would be similar to (if not better than) a class 333. However, they do stress that's just an illustrative example and not indicative of which rolling stock will be used.
The 333s have been funded weirdly. After receiving the extra centre cars for the 333s WYPTE couldn't afford to pay for the centre cars in full and had to be bailed out by SYPTE, who feared that if the centre cars were taken back that Doncaster services would no longer get the 4 car 321s.
I don't know if there's anything to stop them being used on Manchester to Selby/Hull semi-fasts given they would still serve West Yorkshire commuters (Marsden, Slaithwaite, Huddersfield, Dewsbury and Leeds all being West Yorks stations.) Although I think a refit with a high density 2+2 layout (like the EMT 158s) would be appropriate if they were used for that purpose.) Given by the time North TPE electrification is complete the 333s will be around half way through their lives it would be perfect timing for a full internal refit.
There's not even enough 333s to run all the services they were ordered for though. Round about 2000-ish, Metro tried to get the go-ahead (from I think the SRA) for a further 4 or 6 (can't remember which) 333s to replace the 321s. This would have given a uniform fleet for West Yorkshire electrics for a while at least, but we'd still need more than that to cover all the new electrification schemes and we can't get any more 333s. (We could have the 332s from Heathrow Express though)
In any case the 333s might not be on their current Airedale/Wharfedale routes in the longer term if usage continues to grow, due to the fact that platforms 1&2 at Shipley can't realistically be extended beyond 6x23m. If services of this length are required regularly then either the 333s need to lose the 4th car or they need to be deployed elsewhere with something coming in to replace them. 323s would be ideal (indeed the original Airedale/Wharfedale electrification plans proposed a further order of 323s that might have saved the Hunslet plant in Leeds) and would bring them 'home'.
It does make sense to use a 4x23m unit like the 333s as a 'prototype' for future planning though- making some of those platforms any longer would probably be too expensive and a bit of an overkill.
