Im still of the opinion that the answer is 197 and that the timetable should just go back to what it was, with through running across Cardiff.
And I'm still of the opinion that one-nine-sevens (or one-anything-anything, given that denotes a straight DMU), with the benefit of hindsight, shouldn't have been the answer for anyone specifying new-build trains since the late 2000s. In hindsight 172s should probably have been the last straight DMUs built; although the class 196 fleet, with only 26 units, is probably small enough to avoid being too big an issue for decarbonisation the same certainly cannot be said for the 195s and 197s.
I agree that the loss of through-running across Cardiff is a shame, but would argue that running the mark 4s through between Manchester and Swansea, with connecting 175s from Cardiff and Swansea to Carmarthen, would have been a far better way to do it than KeolisAmey's policy of buying a shedload of cheap new DMUs for most things outside the South East Wales Metro.
Yes, some new designs with bimode capability would be good, but the lengths of wires to use the electrical functionality are too short. Even if Cardiff to Swansea gets wired there is still a huge gap on the Marches which makes diesel still come out on top.
Newport to Crewe is indeed a long gap to do on diesel, and
maybe the economics
for the TOC would still come out in favour of a straight DMU under the wires to Swansea and Manchester. However, my main concerns here are:
- reducing GHG emissions rapidly and
- the economics of the electrification
If you have bi-modes on Swansea-Manchester it improves the case for wiring between Cardiff and Swansea, since you can add the fuel savings while under the wires to the benefits when working out the BCR of the electrification scheme. If the only trains you are going to run on a route are straight DMUs, the benefits are essentially zero until you can withdraw the DMUs and replace them with something that can make use of the wires. Yes, in the short term you could cascade the DMUs around to put bi-modes or EMUs on the routes you're wiring, but the alot of the work the Civity DMUs are best-suited to (eg. Liverpool-Manchester (via Warrington Central) stoppers and Shrewsbury-Birmingham stoppers) are also not going to be the last routes that want wiring.
For achieving net zero, there are other areas where more can be done before TfW Marches services come to the top of the list for decarbonising.
Yes, but reaching net-zero is urgent and to get there (according to Network Rail) we need to get through all the higher-priority stuff AND stuff like the Marches. We cannot get to where Network Rail says we need to be while we have (m)any trains that have no ability to pickup power from OHLE or third rail.
In the meantime, we need rail to be wining passengers out of cars. At the moment, cancellations, shortforms, delays and dreadful seats are putting people off rail, some vowing never to travel by train again. We need the opposite - an attractive product that leads passengers to think "this is better than my car, I'll choose rail again in future" and I think a reliable service of mark 4 sets, once lengthened to 5 coaches, is far more likely to acheive that than a reliable service of 5-car 197s. Hence, I don't think we should be in a rush to replace the mark 4s and, when the time comes to do so, it must be with something of comparable (or better) quality - not a massive downgrade in quality as the 197s are.