But it's not 128 DMU's, because the 197s currently are replacing 158's and 175's. Although there's a huge amount of speculation, the original Franchise brief was the 175's to go by Q2/3 2022 and 158's to go by Q1/2 2023 on the assumption that the ERTM's fitted units will be last to arrive.
I seem to recall the last of the units being due for delivery in 2024, at which point several of the 3-car units would be converted to provide first class accomodation (which prior to that point would be declassified). That means the ETCS fitted units, while not the first to arrive, wouldn't be the last either.
I get your point about decarbonisation, but when exactly are you expecting the Welsh network to be electrified? Not any time soon.
There is what I'm 'expecting', what I would want to see and what I think might be 'realisticly acheiveable'. With the current UK Government what I'm expecting is disaster - very little additional electrification and a failure to decarbonise by 2050. What I would want to see is, broadly speaking, full implementation of Network Rail's TDNS proposals in time for the government's 'no more diesel-only trains' target in 2040, but that's unacheiveable. What might be 'realistically acheiveable' is implementation of something approaching the TDNS plan (perhaps minus some of the ancillary electrification) by 2050. In terms of the TfW network, that might look like this in terms of future mainline electrification:
- Wolverhampton to Shrewsbury by 2030 or 2035 (which is when I would envisage class 158 replacement)
- Crewe to Newport and Cardiff to Swansea by 2040
- Holyhead/Llandudno to Runcorn, Warrington Bank Quay and Crewe by 2045
- Shrewsbury to Chester via Wrexham, Briton Ferry to Llanelli and Swansea to Carmarthen by 2050
Also if TfW get these metros and timetable increases right, it should attract car users to the railway, so there's already an influence in reducing emissions.
The metros should attract car users, but the deployment of class 197s on routes (ie. long-distance (semi-)fast services) they aren't suitable for will not exactly encourage car users to flock to the railway. Being diesel-only as cars switch to electric won't help encourage modal shift either.
There are certain routes that are unlikely to ever be wired, so some form of self-propelled train will be needed. Batteries and Bionic Duckweed might work fine for Stourbridge or Butetown but are unlikely to ever be capable of having enough range for the Heart of Wales or Glasgow to Mallaig.
The TDNS has the Heart Of Wales and Cambrian lines down as routes for hydrogen, but between Craven Arms and Shrewsbury, Llanelli and Swansea and Shrewsbury and Birmingham International these would be running under the wires. The Heart Of Wales might not be much of a concern if it stays at 4/5 trains per day, but running the Cambrian services as diesel (or hydrogen) under the wires east of Shrewsbury would be an extremely poor outcome. You need a self-powered fleet capable of making use of electrification to make a strong case for the bits that are wired.
There are a few routes in the TDNS (such as the Cornish branches) where there is no OHLE on route at all but there are more than enough 195s to cover all of those. We don't need the 197s as well.
The CAF DMUs are considerably more fuel-efficient than the 1980s units
I'm not so sure; they are heavier than sprinters and the figures I've found suggest there isn't much in it. The CAF DMUs are more fuel-efficient than 175s though.
There is a case to argue that diesel-electric units would have been better, but the theoretical possibility of converting to bi-mode would almost certainly never happen once the units have a few years under their belt- see the E-Voyager project for example.
This is why I say they should be 'electrification ready', not just that they should be diesel-electric. Voyagers have traction motors, but apparently their lack of through-wiring between vehicles for traction power contributed to the E-Voyager project faultering. Any new self-powered units should have stuff like that in place from new with designs ready for the convertion to bi-mode so that, when the time comes, it's as easy as fitting a pantograph and maybe a transformer; just as 3rd rail EMUs are designed for easy OHLE convertion. The fact that the Voyagers proved 'too hard' to convert just shows that the Civity DMUs are going to lock us into diesel for far too long - we need to stop building them ASAP.
Where the doors are is completely irrelevant to the sort of service the units will run on.
Where the doors are is
almost completely irrelevant, but the
width of them is
very relevant (and the reduction in toilets, seats, tables and legroom in favour of standing room that results).