|/ /1858||Brecon and Merthyr Railway|
Bill presented for line to Dowlais. Backed by the de Wintons and other Brecon bankers. Also backed by GT Clark of the Dowlais Iron Company and John Boyle of the Rhymney Railway. Engineer: Henry Conybeare.
|/ /1860||Hay Railway|
Divided. Hay to Three Cocks Junction was owned jointly by the Hereford, Hay and Brecon Railway and the Mid Wales Railway. Three Cocks Junction to Talyllyn was owned by the Mid Wales Railway. Talyllyn to Brecon was owned by the Brecon and Merthyr Railway. Hay to Eardisley was owned by the Hereford, Hay and Brecon Railway.
|/ /1863||Hay Railway|
The Brecon and Merthyr Railway starts to operate to Brecon.
|01/05/1863||Brecon and Merthyr Railway|
Brecon to Pant opened.
|/ /1864||Rumney Railway|
Machen to Caerphilly partly opened. Rest of route opened as Caerphilly Branch (Brecon and Merthyr Railway).
Act for Caerphilly to Cardiff Line (Rhymney Railway) and connection to the Caerphilly Branch (Brecon and Merthyr Railway). Traffic agreement made with the London and North Western Railway. Larger company helps finance smaller company's plans.
|/ /1865||Rumney Railway, Brecon and Merthyr Railway|
Rumney Railway purchased by the Brecon and Merthyr Railway.
|/ /1866||Thomas Savin|
Becomes bankrupt. Leads to near bankruptcy of the Brecon and Merthyr Railway.
|01/08/1868||Brecon and Merthyr Railway|
Branch to Merthyr opened. Engineer; Alexander Sutherland.
|01/11/1868||Deri Branch (Rhymney Railway)|
Line opened from Bargoed North Junction to Deri. The Brecon and Merthyr Railway had running powers of this from Deri to the main line of the Rhymney Railway and from there to the junction with a spur from the Rumney Railway.
|01/11/1868||Extension to Rumney Railway (Brecon and Merthyr Railway)|
Northern section opened from Pant to Deri. The Rhymney Railway had running powers from Deri to Fochriew and Pantywaun for freight and had a connection from Fochriew to the Taff Bargoed Joint Line.
|23/06/1869||Brecon and Merthyr Railway|
Pant to Dowlais Lloyd Street opened. Connected to the Ivor Ironworks. (Named for John Guests heir).
|/03/1870||Brecon and Merthyr Railway|
Aber Bargoed re-opened.
|/ /1871||Brecon and Merthyr Railway|
Made available to all companies running to Brecon.
|01/01/1873||London and North Western Railway South Wales|
Line extended to Dowlais Top and Ivor Junction with the Brecon and Merthyr Railway and access to Dowlais Lloyd Street and the Dowlais Iron Company.
|/11/1873||London and North Western Railway South Wales|
Bill for line to Merthyr and the Brecon and Merthyr Railway, Vale of Neath Railway and Geothin Railway.
|16/05/1874||Vale of Neath Railway|
Train heading towards Neath breaks loose and runs into Merthyr station. It collides with a Brecon and Merthyr Railway train. One killed and fifty injured.
|18/05/1874||London and North Western Railway South Wales, Brecon and Merthyr Railway|
London and North Western Railway agrees to withdraw Merthyr bill in exchange for joint ownership of the Brecon and Merthyr Railway branch from Dowlais to Merthyr. A link was to be opened from Penywern Junction, by Ivor Junction, and run from there to Morlais on the Brecon and Merthyr Railway.
|08/08/1878||Pontypridd, Caerphilly and Newport Railway|
Act passed. Promoted by J.C. Parkinson of the Alexandra Docks and Railway and Sir George Elliot of Powell Duffryn Collieries. Double track line to run from south of the Taff Vale Railway's Pontypridd station (Pontypool, Caerphilly and Newport Junction Railway) to Caerphilly (Penrhos Upper Junction) on the Rhymney Railway. Running powers over the Brecon and Merthyr Railway's Caerphilly Branch to Machen and on to Bassaleg Junction with the Alexandra Docks and Railway. Engineer Sir James W. Szlumper.
|02/12/1878||Brecon and Merthyr Railway|
Northbound train at Torpantau fails to have its brakes pinned down and runs downhill derailing and killing its crew.
|14/09/1891||Caerphilly Branch (Brecon and Merthyr Railway)|
New 'up' (eastwards to Newport) route opened between Gwaun y Bara Junction and Machen. Known as the 'Machen Loop' Line. This effectively doubles the route.
|/ /1905||Brecon and Merthyr Railway|
|02/01/1905||Rhymney Valley Branch (Barry Dock and Railways)|
Line extended from Penrhos Lower Junction to Barry Junction on the Rumney Railway of the Brecon and Merthyr Railway opened. Penyrheol Viaduct and Llanbradach Viaduct on the line opened.
|01/09/1905||Brecon and Merthyr Railway|
Aber Bargoed renamed Aber Bargoed and Bargoed.
|/ /1906||Rhymney Branch (Brecon and Merthyr Railway)|
Whiterose renamed New Tredegar.
|14/04/1930||Brecon and Merthyr Railway|
|17/09/1956||Pontypridd, Caerphilly and Newport Railway|
Caerphilly Branch (Brecon and Merthyr Railway)
Passenger service from Pontypridd to Caerphilly and Machen withdrawn.
|02/05/1960||Brecon and Merthyr Railway|
Dowlais Central (formerly Lloyd Street) closed to passengers.
|/ /1962||Brecon and Merthyr Railway|
Brecon (Free Street) closed.
|31/12/1962||Deri Branch (Rhymney Railway), Extension to Rumney Railway (Brecon and Merthyr Railway)|
Line closed to passengers.
|31/12/1962||Brecon and Merthyr Railway|
Closed to passengers from Brecon to Newport.
|01/04/1963||Extension to Rumney Railway (Brecon and Merthyr Railway)|
Line closed to freight.
|01/07/1963||Caerphilly Branch (Brecon and Merthyr Railway)|
Caerphilly to Newport workmen trains withdrawn.
|23/08/1965||Deri Branch (Rhymney Railway), Extension to Rumney Railway (Brecon and Merthyr Railway)|
Line closed to freight.
|/10/1966||Brecon and Merthyr Railway|
Merthyr to Vaynor Quarry closed.
|20/11/1967||Caerphilly Branch (Brecon and Merthyr Railway)|
'Down' section closed, traffic diverted via Penrhos, Walnut Tree, Radyr and Cardiff.
This line is divided into a number of portions.