Of course some of the freights between Margam and Llanwern could also use electric traction if Maragm yard and the relief lines east of Cardiff etc are wired.
Where are Theale and Westerleigh (or whatever the eastern destonations of the trains from the Robertston oil refinary near Milford Haven)? Also, where do the steel trains from Llanelli and Port Talbot go? Although Llanelli and Robertston will be beyond the wires, the freight-operator could probablly save alot of emmisions by running a 90 or 92 to Margam and putting the diesel loco on there for the trip out west (would still be a diesel under the wires from Margam to Briton Ferry, but that's probably alot less than if they remain diesel hauled for their entire journey).
As I have pointed out before,Maesteg is to get a half hourly service. I have a sneaky feeling that common sense will prevail and that the wires will go to Swansea.
I hope your sneaky feeling regarding Swansea is correct. Just a few months to go until the plan has to be signed-off though isn't it? I wonder if the extra Maesteg services will terminate at Bridgend or become extensions of one of the two Vale Of Glamorgan line services each hour. Certainly I don't support the idea of terminating the Swanline service at Port Talbot to allow the extra Maestegs to use the main line between Cardiff and Bridgend.
Actually I wonder if the DfT aren't playing a rather sneaky game with regards to Swansea and electrification. By leaving it off the GWML electrification I wonder if they aren't trying to persuade the WAG to fund the wiring of that part of the route saving themselves some cash in the process, but if the WAG doesn't go for it for whatever reason, they are still open to reversing their decision in the future (by making part of the Valley Lines electrification perhaps). Maybe it's a bit too sneaky for them but I wouldn't be surprised if there are elements within the DfT that are hoping that the WAG are going step in and pay up for wiring to Swansea.
In my opinion it is 2016-2018 or never. If it is not done then, doing it later would almost certainly incur the start-up costs and DaFT would have ordered their daft IEP bi-modes for the job. Of course the diesel engines could be taken out of the IEPs, but given the cost of procuring the diesel engines in the first place* I doubt that idea will be given much consideration. The IEPs will then mean parts of our Intercity network being run with diesel trains until 2050. If such poor-enviromental-thinking continues, life on earth might not have long to live by then. If the planned quantity of bi-modes is ordered, any prospect of Swansea electrification is probablly dead.
*Modern Railways' Informed Sources says £250,000 per engine. With the numbers from the consultation document (11 'electrics', 26 5-car bi-modes and 12 8-car bi-modes) that's £37,250,000 or £34,250,000 (depending on whether an 8-car bi-mode has 4 engines or 5). £2,750,000 of that is going just on emergency generators on 'electric' sets. DAFT!
My priority would be to electrify enough (in the UK) to free up around 150 DMUs (replacing all of the Pacers plus allowing many 153s to be permanently attached to others)
My first priority is to avoid a new fleet of Intercity DMUs. Intercity should go as electric as practical (the odd diesel loco would be required for infrequent extensions over slow routes, but the hourly (or greater) cores of the Intercity network should all be electrified). Replacing pacers is second on the list.
Crewe - Chester electrification in the next WCML franchise.
If that happens, then in my opinion ICWC should go all-pendolino (with the possible exception of the Pretendolino, or anything else electric-powered, lacking any form of diesel powerplant (or other unecessary heavy stuff) and well suited for Intercity work). It is a shame the class 57 thunderbirds have drifted away, since they would be needed to maintain the Holyhead and Bangor services. That would require the purchase of additional Pendolinos, but would release ICWC's class 221 fleet (which hopefully will become 7-car bi-modes). They in turn could release 5-car class 220 bi-modes from XC for Paddington to Worcester/Hereford and the Westbury semi-fasts (with bi-modes on the Cotswolds, the small fleet of 180s with GW could cover most, if not all, the extended semi-fasts to Exeter/Paignton).
With great power comes great responsibility, and potentially great cost...
As I've said before though, funding rail infrastructure is
NOT WAG's responcibilty. There are (apparently) ways they can do it, but quite what these are I do not know as that is not devolved and so they don't get a slice of UK tax revenue for that purpose in their budget from Westminster.