Surely, what its needed is a shuttle bus service between Heath Halt and Heath Hospital along with the provision of a hard paved footpath connecting these two points with the shortest possible route? An add on fee of say 50p return could be added to the train ticket to provide the bus link. Why are the Welsh Government/ Transport for Wales not organising this now along with a similar bus link from Cogan station to Llandough Hospital? It seems to me that the only organisation showing any initiative is NAT Buses who have pioneered new cross city routes which Cardiff Bus are now copying to some extent having previously been all for people changing in the city centre.
The whole Heath area is swamped with cars during the working week as poorly paid hospital staff dump their cars wherever it is free to park. A rail link from Coryton to either Radyr (for a circle line) or Taffs Well would provide a vital link with the Taff valley for connection to Heath Halt. Any deviating / additional stops on the fast rail route from Heath Halt to Queen Street will make the Coryton branch (& Rhymney line) less attractive to commuters.
I see that many on this forum are speculating on services and types of trains needed. Are we just talking to ourselves? Does anybody with power actually read this stuff?
Here is a map showing the Hospital and Heath Halt stations for those who are not familiar with the area. (Traffic flows on the roads have been enabled and will be live at the time you click the map).
https://www.google.co.uk/maps/@51.5102943,-3.186299,1524m/data=!3m1!1e3!4m2!17m1!1e1!5m1!1e1