Fochriw was on the Brecon and Merthyr Railway line from to . The Bargoed branch of the Rhymney Railway ran north from Bargoed to , then the B&M constructed the line from Deri northwards, through Fochriw. Each company had running rights, with the Rhymney running as far north as Fochriw Colliery, past a number of other collieries in the Darran valley. The Rhymney section to Deri was opened in 1864, but the B&M did not open through Fochriw to Dowlais Top until 1 September 1867, as they had been legally obliged to complete their connection from Dowlais to Merthyr first. The line through Fochriw may have been completed some years before this, and coal shipped northwards from the colliery, but the line was not yet officially opened for passenger service. Increasing coal traffic southwards from Cilhaul and Ogilvie collieries after 1900 led to the Rhymney section being relaid as double track. The Ogilvie Colliery at Deri was sunk between 1918 and 1923.