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.
Merthyr Tramroad
In 1823 a Bill was unsuccessfully promoted to extend the line to Cardiff. It was some of the same promoters who obtained the Act for the Taff Vale Railway in 1836. Although the Taff Vale Railway opened to Merthyr in 1841 it wasn't until 1851 that the standard gauge Dowlais Railway was completed allowing through running to its works. Penydarren Ironworks closed in 1859. Plymouth Works didn't cease iron production until 1880 but had built a standard gauge line over part of the tramroad in 1871. South of Mount Pleasant the disused tramroad was lifted in about 1890.