The introduction of new trains and the 'final' metro timetable would perhaps address the timing issue.

The recent increase of the service to Rhymney to half-hourly looks like a bit of a temporary solution. 1tph runs non-stop Bargoed-Rhymney, and 1tph makes all the stops. The previous timetable had all train stopping, but 1tph; at peak times approx 3tph ran through, but in one direction only, with the peak trains going in/out of the sidings at RHY, and nothing running in the other direction - I think it was a 2hr gap back to Cardiff in the evening peak. Since going to 2tph all day, the newish passing loop at Tir-phil isn't used, and this will be why only 1tph makes the intermediate stops - without using the loop, the single track section is just too long for 'proper' 2tph. I suspect this is an interim solution so that RHY-BGN can have captive diagrams, as 231s are not yet authorised to BGN, and the mainline crews that work the VoG leg don't yet sign them. (AIUI)

Given the above, I suspect when a more final timetable is implemented, a better timetable using the Tir-phil loop will be introduced as everything on the RHY-BYI/BGN axis will be 756s, so captive diagrams are no longer needed. So at that point maybe longer turnarounds will be possible. Also a timetable optimised for new trains will hopefully be a bit quicker (even if only on the electrified Rhymney leg) and therefore perhaps have more room for the extra stops. And when the VoG goes half-hourly hopefully that improvement would be seen as a reasonable trade-off for any time added by extra stops.

 

Bridgend council want a station at Cowbridge road  in Bridgend on the VOG basically where the line passes behind Tescos. The college is being moved closer to the town centre however a lot more housing is being built in that area abd a station there is certainly in demand

 

I took a more detailed look at this before I posted without comment yesterday - whilst I have travelled the lone, I have only that as local knowledge, but three things have struck me:

1. The 3 minute turn around in the current timetable at Bridgend which would be compromised by an extra stop.

2. The closeness of St Athan to Llantwit Major

3. The LONG distance from Llantwit to Bridgend which (?) must be one of the longest inter-station gap anywhere on the valley lines.

 

The line needs a half hourly service first. Therescat least 2 stations that need reopening between Barry and bridgend these being:
St Athan
Cowbridge Road (Bridgend)

 
From Wales Online