The Merthyr Line is a railway line in South Wales from Cardiff to Merthyr Tydfil and Aberdare. It is historically the Taff Vale Railway, the first rail development in the Valleys in the 1840s and associated with the notorious Taff Vale Judgment in 1901 when the courts penalised trade unions for losses caused by strikes.
The line follows the Rhondda Line as far as Pontypridd, serving Cathays, Llandaff, Radyr, Taff's Well, Trefforest and Pontypridd. It then divides at Abercynon with separate branches to Merthyr Tydfil and Aberdare up diverging valleys.
The Merthyr branch serves Merthyr Vale, Troed-y-rhiw, Pentre-bach and Merthyr Tydfil. The Welsh Assembly Government confirmed in February 2007 that it is grant funding, in conjunction with European Union Objective 1 assistance, a scheme to upgrade the line north of Abercynon, including reinstatement of 2 miles of double track, to enable the introduction of a half hourly train service (currently hourly), the revenue costs of which the Welsh Assembly Government will also meet. The enhanced service is said to commence sometime in 2008.
The Aberdare branch serves Penrhiwceiber, Mountain Ash, Fernhill, Cwmbach and Aberdare. The line continues beyond Aberdare - for good purposes only - to serve Tower Colliery, the last deep coal mine to remain open in South Wales. Mountain Ash station was redeveloped with a grant from the Welsh Assembly Government in the early part of the decade, the scheme including the provision of a new station and a passing loop to permit an upgrade of the passenger service to two trains per hour from late 2003. There are a few gaps in the half-hourly service to enable coal/stone trains to run to/from Tower Colliery/Hirwaun. In 2005, following further grant from the Welsh Assembly Government, the stations at Abercynon, Penrhiwceiber, Fernhill, Cwmbach and Aberdare were extended to four-car length to accommodate longer peak trains in an initiative to relieve overcrowding, train leasing/running costs also funded by the Welsh Assembly Government.
Although there has been some thought to reopening the line beyond Aberdare to Hirwaun, a study in 2006 by SEWTA (the local transport alliance) appears to rule out any such extension for the foreseeable future.
The line is currently operated by Arriva Trains Wales (ATW) as part of the Valley Lines network. ATW replaced the previous franchise, Wales & Borders Trains in December 2003. Merthyr Line - Principal stations Cardiff Central
Cardiff Queen Street
Cathays
Llandaff
Radyr
Taffs Well
Trefforest Estate
Trefforest
Pontypridd
Abercynon North Abercynon South
Penrhiwceiber Quakers Yard
Mountain Ash Merthyr Vale
Fernhill Troed-y-rhiw
Cwmbach Pentre-bach
Aberdare Merthyr Tydfil | 
