Hasn't the A483 taken over the trackbed in places south of Llanymynych?
There are probably river/canal bridges to rebuild too, not to mention the heritage incumbents on the remaining track.
From a quick look at Google maps, there is track still in-place practically all the way from Gobowen to Llynclys save for about 350 metres through sombody's back garden (not their house, I think) at the latter. Then there are a few buildings on the trackbed between Llynclys and Llanymynech, mostly agricurtral/industrial type buildings not residential judging by the aerial photography. The A483
doesn't appear to have taken over the trackbed. At least one bridge is missing however and there are more agricurtral/industrial buildings on the trackbed (and houses very close to it) between Llanymynech and the junction with the Cambrian Main Line.
Overall, reopenning Gobowen-Oswestry/Llynclys looks fairly straightforward but completing the full link might require a new alignment in a few places.
Is re-opening Gobowen to Oswestry feasible? And would it make any kind of sense to extend the Bidston/Wrexham trains to incorporate this extra leg?
As noted above, there is still track in place so reopenning Gobowen to Oswestry really ought to be feasible. With the plan to increase the Borderlands line service to 2tph, with one being limited-stop, it also ought to be possible to run the limited-stop workings through to Oswestry instead of Wrexham Central, leaving the latter with hourly stoppers. However, unless that could be extended into Liverpool (requiring something like the Ultra class 73s or new 3rd rail bi-mode units to avoid running diesel engines in the Merseyrail tunnels) I doubt there would be much demand for the through link; Oswestry-Wrexham-Chester would be more useful but there's the single line section north of Wrexham to scupper that.
The way I see it, those south-facing bay platforms at Wrexham General could be useful for more than just overnight stabling/servicing of a handful of class 230 units...
First things you need to ask are what does it unlock? Is there a suppressed demand which cutting the corner of Shrewsbury opens up? Also bear in mind the implications it has on the rest of the Cambrian, unless the plan is for this new link to take one of the hourly paths. Clearly Oswestry gains but where do people from there go and want to go? Surely the majority is towards Wrexham/Chester?
Good point; the demand from Oswestry is more likely to be north to Wrexham than south to Welshpool, which given north of Oswestry is the easy bit does point towards only bothering with that section and leaving the hard bit from Oswestry to Welshpool without rails (but can we have a strict policy of safeguarding possible rail routes from future development please?). Cutting the corner would improve links from Aberystwyth, Machynlleth, Newtown and Welshpool to Wrexham, but if there was really all that much demand it would be possible to run a through service between Aberystwyth and Wrexham via Shrewsbury without any reopenning required (although to avoid removing the Birmingham link you'd want more double-track on the Cambrian to allow such services to be additional workings over and above the (to be hourly, I hope) Aberystwyth-Birmingham services.
Without additional double track on the Cambrian, any services between Oswestry and Welshpool should terminate at the latter in my view. If money was no object (eg. a Barnet consequental from HS2 ring-fenced for new rail infrustructure), I would suggest lots more double track and new lines (on brand-new alignments in several cases, avoiding circuitous historical routes) Merthyr-Brecon-Newtown, Porthmadog-Bryncir-Caernarfon-Bangor and Welshpool-Oswestry-Gobowen. Service pattern would be:
- Aberystwyth-Birmingham (hourly)
- Pwllheli-Birmingham (every two hours, portion-work with above)
- Brecon-Cardiff (every 30 minutes)
- Brecon-Newtown (hourly) continuing in alternate hours to Wrexham (via Oswestry) and Bangor (via Porthmadog)
- Newtown-Welshpool-Oswestry-Wrexham (every two hours, creating an hourly service over this section)
- Pwllheli-Porthmadog-Bangor (every two hours, building these two sections of route up to hourly as well)
At the very least, I feel that the Porthmadog-Caernarfon-Bangor and Oswestry-Gobowen-Wrexham elements of the above should be persuded before considering a new line between Carmarthen and Aberystwyth. Even Oswestry-Welshpool might end up being better value than Carmarthen-Aberystwyth (with a service every two hours Bangor-Caernarfon-Porthmadog-Machylleth-Welshpool-Oswestry-Wrexham) due to the two (very expensive) tunnels needed to make Carmarthen-Aberystwyth make sense with the private car as a competitor (Merthyr-Brecon-Newtown would similarly require new alignments with expensive new tunnels to avoid the circuitous historical routes, the new alignment needed from Bryncir to Porthmadog I doubt would require a tunnel).