The 'Junction' suffix refers to the fact that until the early 1980s, there were two junctions near here – one to the south between the current line via Caerphilly (which opened in 1871) and the original route down the Big Hill via Penrhos Junction to Walnut Tree Junction near Taffs Well on the Taff Vale Railway route from Cardiff to Merthyr Tydfil and another to the north for the branch line to Senghenydd.

The former opened in 1858 and provided the Rhymney company with its original access to Cardiff General and the docks.

It was freight-only for most of its life, but was heavily used in post-grouping and BR days by coal trains originating from the various collieries on the Rhymney line heading to the marshalling yard at Radyr.

The Senghenydd branch passenger service ended in June 1964 as a result of the Beeching Axe, but it remained in use for colliery traffic until 1977[1] whilst the Taffs Well route closed in June 1982[2] – both have since been dismantled.

[4] In the evenings, the service dropped to hourly, and on Sundays to two-hourly (with southbound trains running to Barry Island).