If I know that route as well as I think I do, the trains can only go 5mph north of Tondu until they've cleared the junction. For it to be that slow and that bad a ride is quite astonishing.
Don't get me wrong, you are not thrown from side to side, but the fact that is so slow makes you realise how uneven the track is. I suspect the sleepers are sinking into the ground. The train gently sways from side to side, which it wouldn't do if the sleepers were in firm ground or the ballast was tamped properly.
Just been to Aberdare on the last day of the £1 PAYG offer.
The conductor warned me not to get off on the new 'arrivals platform' as it doesn't have a Tap In/Out unit. Not that its broken, it just doesn't have one! not even a place where it should go.
So me and most of the trains passengers waited for about 3 minutes until the signals allowed the train to move 100 metres to the old platform. Why on earth build a new platform, call it the arrivals platform and not put in a device on it?