I used to be based at RAF Brize Norton so I know the Cotswold lines well! Plus my partner used to live in Stow. The mistake was made with the voyagers making them too short. Looks like its gonna happen again with IEP. Plus like I said in a previous thread the bi-mode idea is jus ludicrous! Even the press think its stupid.
So your answer for serving routes that will be part-electrified and part-unwired is what?
And if you know the area as you claim to do, then where, using some of this local knowledge, are all your fantasy extra passengers are going to come from all of a sudden to fill a 600-seat train off-peak?
The story of the Cotswold Line for the past 30-odd years has been one of slow, steady growth. The one time there was a big spike was 20 years ago immediately after the Turbo service launched, bringing back through London services across the day, not just in the peaks. You are not suddenly going to go from running well-loaded 280-seat trains off-peak to running well-loaded 600-seat trains.
Cut the cost of peak travel for through travellers to the same price as those who split their journey at Diddyland?
We're not talking about filling peak trains on either route - that is never going to be a problem - we're talking about the fantasy that you can fill a 600-seat train outside the peaks beyond Oxford and Swindon. And next to none of the Cotswold Line trains call at Didcot anyway.
Heathrow Express seem to do this all day every day and make a profit for BAA
With fares more expensive per mile than Concorde used to charge, it's not hard.
The problem seems to be this:
There is demand for 5+ trains between Worcester and Oxford. (The 180 services during the day from Great Malvern are normally full up & one of the main aims of the CLPG is an hourly service between Great Malvern and Paddington.)
There is probably not the demand for 10 car beyond Worcester/Great Malvern.
The problem is that multiple is problematic where you have short platforms between Worcester and Oxford - Hanborough is the obvious example which is limited to 2 HST cars.
You've got passenger demand that means that trains have to stop at Hanborough, but you don't have trains at 5 coaches that are long enough to accommodate all the passengers for journey beyond Oxford, and you don't have the infrastructure (longer platforms) to accommodate trains running in multiple.
Something has to be fudged - the 'best' solution from the point of view of the passenger would be 8/9 car IEP, or double tracking, or lengthening the platforms.
The lack of traffic between Great Malvern and Hereford is perhaps in part due to the fact that the service is so poor at the moment, and are the costs of running an 8 or 9 car bi-mode between Hereford and Great Malvern so significantly higher than running a 5 car bi-mode between those same places?
The most likely outcome is going to be 5 car and over-crowding.
As a more abstract suggestion, since I have noticed other discussions about class 222s going to GW in the future, how about using some 222s on the Cotswold Line, perhaps reformed into 7 car formations. I don't know about the logistics but with a suitable interior set-up (perhaps DMS-MS-MS-MS-MS-MC(with mini-buffet)-DMF?), they could offer a capacity improvement on a Class 180/5-car IEP whilst not being completely empty like some off-peak HSTs.
Are 222s fitted (or can be fitted) with SDO?
If that worked then you could even make the 222s bi-mode...
I can only see 5-car IEPs to Worcester and Great Malvern as a disaster waiting to happen, however 10 cars would be overkill (and also not fit at any stations on the Cotswold Line).
The actual problem seems to be this - neither of you has taken in what was said by cjp and THe Ham at the botom of page 1 of this thread. I have since looked up the technical specifications for IEP, released earlier this year by DfT.
The section on the selective door system says that the system will allow - either guided by GPS, ETCS signalling (if available) or by crew control - any combination of doors in any position on the train, or trains, to be opened. From this it is seems fair to assume that the way 2x5 formations will work is stop with the middle of the formation on short platforms, like those on the Cotswold Line and down the Stroud Valley,
so that doors on parts of both sets can be opened. The formation will not draw up neatly with the nose or back next to the ends of the platform, they will stick out at both ends.
I remain of the view that a modest number of eight or nine-car bi-modes would be useful on GW services but having the entire fleet like this would make no sense at all. The situation between 2009 and last year, when the only stock FGW had available to work the Cotswold Line was an HST or a Turbo, with nothing available offering an intermediate level of seating capacity combined with inter-city comfort, instead of cramped 3+2 Turbo seats, was plain stupid.
The specification document is here
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/82840/tts-redacted.pdf and the stuff about the SDO system is on pages 45-47.
The 180 services are not all full up west of Oxford - some are near-full, some aren't. The ones that are busy are the ones that are giving FGW cause for concern in terms of the effects of future growth in traffic if most IEPs are five-car - hence all the stuff I keep having to repeat about what the GW franchise invitation to tender said about how an operator could go about requesting other formations.
How on earth you can say that the service between Great Malvern and Hereford is poor baffles me, when it is pretty much the best it has ever been, with an hourly LM service to and from Birmingham - many connecting with FGW at Malvern or Worcester - plus FGW running six through trains to London and five from London on weekdays, plus a Sunday morning service on the line for the first time in years. And Hereford passengers also have the option of going via Newport if they don't mind the change of trains.
Forget 22xs of any sort. They cannot carry enough passengers - a seven-car has fewer standard class seats than a five-car 180. Even if you converted some of the first class seats, you would just about break even with a 180 - in a train that is 56m longer and is not going to be turned into a bi-mode.