The Conwy Valley Line is a railway line in north Wales. It runs from Llandudno via Llandudno Junction (Welsh: Cyffordd Llandudno) to Blaenau Ffestiniog, and was originally part of the London and North Western Railway, being opened in stages to 1879. The line from Llandudno Junction to Blaenau is single track, and includes the longest single track railway tunnel in the United Kingdom (over 2½ miles / 4.22 km). Between Llandudno Junction and Llandudno the service uses the double track branch line from the North Wales Coast Line. The primary purpose of the line was to carry slate from the Ffestiniog quarries to a specially built quay at Deganwy for export by sea. The original plans envisaged a railhead at Betws-y-Coed (where a large goods yard was laid out) with a narrow gauge line via the steeply graded Lledr Valley to Blaenau Ffestiniog. The line also provided goods facilities for the market town of Llanrwst, and via the extensive facilities at Betws-y-Coed on the London to Holyhead A5 turnpike road it served many isolated communities in Snowdonia and also the developing tourist industry. The first section from Llandudno Junction to Llanrwst (now called North Llanrwst) was built by the Conway and Llanrwst Railway Company and opened in 1863. The LNWR took over in 1867 and opened the extension to Betws-y-Coed in 1868. The fully signalled passing loop at North Llanrwst is the last remaining between Llandudno Junction and Blaenau Ffestiniog.
The train service is operated by Arriva Trains Wales and is being marketed as the Conwy Valley Railway (Welsh: Rheilffordd Dyffryn Conwy). A feature of the service is the availability on Conwy Valley trains as well as on local buses in Snowdonia of the popular "Gwynedd Red Rover" day ticket.
The towns and villages served by the route are listed below.
The original line terminated at the North Western station (where there were extensive slate yards) to the west of Blaenau Ffestiniog town centre. However, following the closure and removal of a section of the former Great Western Railway line from Bala, a short section of new railway was built along side the Ffestiniog Railway Company's narrow gauge line in order to connect the Conwy Valley Line with the isolated section of the GWR line, which had been retained to serve the nuclear power station at Trawsfynydd. Years later a new Blaenau Ffestiniog station was constructed in the centre of the town. Beyond the new station, the line was used only for goods traffic connected with Trawsfynydd, although occasional special passenger trains have been run at times. In recent years, the traffic from Trawsfynydd has ceased completely and the line has been disconnected from the Conwy Valley Line just outside Blaenau Ffestiniog station.
There are connections at Llandudno Junction with the North Wales Coast Line (the main line between London and Holyhead) and at Blaenau Ffestiniog with the Ffestiniog Railway to Porthmadog.