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
The first main line of the Taff Vale Railway, between Merthyr and Cardiff, was opened on 9 October 1840, and by that time the emphasis there had been a significant change of emphasis. The potential of the district for coal extraction had become clear: iron was still important, but the main traffic was now seen as the movement of coal from existing and new collieries, to Cardiff and to the ironworks. The first main line included a rope-worked incline near Quaker's Yard: to overcome a large and sudden ascent there, a length of double track was installed together with a stationary steam engine, and passing trains were hauled up and let down on a rope. The times of the trains were arranged so as to pass up and down at the same time, to some extent balancing the load.