The now defunct Maerdy Branch along the Rhondda Fach valley to Maerdy and the collieries at Mardy and Ferndale used to diverge from the 'main line' to just north of the station at Maerdy Junction. Opened in stages between 1849 and 1856, the passenger service over this route ended in 1964, but mineral traffic to Mardy Colliery continued to run until final closure of the branch in August 1986, when coal from Mardy was then raised from Tower Colliery. The track was subsequently lifted in 1996, but the old formation can still be traced (along with the former up loop platform used by branch trains).
