Well, given that the specification is for the next ScotRail franchise the full rolling stock plan will be released at some point after the franchise is awarded.
Just to add, the franchise will be awarded in October 2014, to commence in late March 2015.
Presumably, we will find out what option the winning bidder has chosen for the "inter-city initiative" quite soon after the franchise has been awarded, as far as whether they will be using existing or new-build rolling stock is concerned, and perhaps the form the stock will take if the franchisee proposes using existing stock. As well as the "easy option" of refurbishing the existing 170s, there will be plenty of high-powered regional/long distance diesel rolling stock becoming available towards the close of the decade in suitable numbers to cover Scotrail's long distance diagrams, in the form of the 185s from Transpennine and the Meridians from the MML.
The announcement of the chosen form of the EGIP rolling stock will presumably take longer to become clear if a tender for it's construction and maintenance has to be issued first, but you would hope that the process will then move forward at a fair pace as the first of the new trains (sufficient to operate a peak time 7-car diagram) have to be in service on EGIP from December 2016, with full fleet deployment a year later.
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Instead of worrying about 8-car 23m units, perhaps they should just bite the bullet and buy 9 car Desiro Cities.
As has already been said, Desiro City isn't an option as the ITT stipulates 7, and later 8, carriage formations of
23 metre carriages.
Perhaps I'll be proved wrong, but I can't see fixed formation 7 car trains (initially), later extended to 8 by inserting an additional carriage, being probable either. While it is not specifically stated in the Invitation to Tender, Transport Scotland are possibly envisaging a mix of 3 and 4-car units being utilised to form 7 and 8-car trains when they talk about the limitations of the stabling facilities at Eastfield, where the headshunt is stated to be able to accomodate 3 x 23 metre carriages but not 4 (rather than being worded as "more than 3" to cover longer fixed formations). This seems most likely.
While it is all pie-in-the-sky thinking on my part, and slightly off-topic as the rolling stock for EGIP is a separate initiative under plan 6, surely it would be logical for an initial batch of 3-car units to be built for EGIP, followed (though starting almost simultaneously) by a rolling programme of 4-car units, first to work alongside the 3-car units forming 7-car trains from December 2016 onwards, and then to oust the 3-car units altogether from EGIP from December 2018 (when 8-car working is scheduled to start) and initiate a mini-cascade to put the 3-car units on the HLOS Dunblane/Alloa/Stirling electrified serviceS, which are also due to start in December 2018.