Llantrisant and Taff Vale Junction Railway
In time the Canal became overwhelmed by the volume of traffic, and encouraged by the successful opening of railways with more advanced technology than the horse tramways of previous years, the Taff Vale Railway was promoted. It was authorised by Parliament in 1836 and it opened between Merthyr and Cardiff docks in 1841. The line passed close to the Maesmawr workings but did not make a connection.
Llancaiach Branch
After much rivalry in securing authority for the line, the Rhymney Railway and the Great Western Railway agreed to sponsor jointly a line from Llancaiach to Dowlais, to get access to the thriving iron and steel works there. The line was authorised on 15 July 1867, and was known as the Taff Bargoed Joint Line. The authorising Act gave the Taff Vale Railway running powers over it. The TVR already had access to Dowlais ironworks, but this was over the Dowlais Railway, which had an obsolescent rope worked incline. The Taff Bargoed line opened to goods and mineral traffic on 10 January 1876, and to passengers on 1 February 1876, although the intervening terrain was very thinly populated.