There are only 5x 3-car 158s with GWR, after they returned most of the 3-cars they had to 2-car to increase 4-car service provision. Therefore, eight 5-car diagrams won't be possible if only 1x diagram remains Turbo-operated; the best we could hope for is 4-5x 5-car diagrams and the remainder 4-car.
Only 158798 was ever a true 3-car set (as far as FirstGW/GWR is concerned) though wasn't it? The rest could presumably be formed into hybrid 3-car sets again as before. I still think the big question is how many train formations you actually need to reliably cover the eight diagrams. Nine 5-car trains would of course be 45 carriages, so if you only need one spare train then GWR would only need four more class 158 vehicles to reach that total (hence my interest in whether there were any odd vehicles left in store from the Salisbury collision).
Both 158763 and 159102 had all their cars written off.
Thanks for the correction. Shame Wikipedia got that wrong as the 3 vehicles that suggested might be available would have almost made up the numbers (eg. GWR could have formed up eight 3-car and ten 2-car class 158s, enough to cover the Cardiff-Portsmouth with 5-cars on a good day but with the spare train only being 4-cars).
Bristol to Plymouth does have an hourly fast service with long distance rolling stock. The GWR service does a reasonable job at linking lots of intermediate centres with each other, and also provides a direct link from South Wales to the West Country, with decent rolling stock.
At the moment have the ongoing farce of Cardiff-Exeter (about 2hr 40min) getting 5car IETs, and Cardiff-Portsmouth (serving bigger population) taking around 3hr 20min (so longer duration) making do with mix of 3-5car 158s and ex suburban 165s.
I agree; if GWR were going to use 5-car IETs on any non-London routes then the Cardiff-Portsmouth would be more-deserving of that than Cardiff-Exeter in it's current form, the latter being where I'd put outer-suburban DMUs (like the 166/165s).
Whilst it is a all station stopper I've witnessed significant numbers of people using these trains and over reasonably significant distances, as such I was using intercity as a example although a good regional unit would be better.
In my view, the InterCity (currently under XC) services between Birmingham/Cheltenham and Devon/Cornwall should be timed to overtake the Cardiff*-Exeter while the latter is in Weston-Super-Mare (ie. between Bristol and Taunton) to encourage longer-distance passengers to change at Bristol and avoid the farce of using stock optimised for dwell times (165s/166s, with their wide doors) on a regional
express (Cardiff-Portsmouth) and long-distance-express stock with longer dwells and less standing space (eg. 158s, 175s and IETs) on stoppers (like the current Cardiff-Exeter services).
That, or put a seperate stopping service in and bring back Cardiff-Penzance or Plymouth as a through service (worked by the 175s in pairs (ie. 4-6 coaches per train) with uncoupling in service being forbidden) but running fast and direct, not stopping via Weston-Super-Mare etc., to supplement/compete with XC as an express service.
* (although, to optimise things for Filton Bank electrification, I think it should be split at Bristol with class 387s (or similar) doing the Cardiff-Bristol stoppers, perhaps with the Exeter stoppers projected through to Cheltenham/Gloucester)
When GWR Devon and Cornwall get the 26 175s with 19/20 150s and 5/6 turbos sent down from Bristol they will be able to easily cover all diagrams with the appropriate stock.
Given that the 175s are to be based out of Plymouth Laira, GWR will
not be able to easily cover all Cardiff-Portsmouth diagrams with appropriate stock (ie. 5-car regional express stock). That could have been covered with the 175 fleet, but for that to work the 175s would have to be maintained elsewhere than Laira (probably Bristol St. Philip's Marsh).
