Transport for Wales (TfW) has announced significant progress in its intensive eight-month programme to transform and electrify the Rhymney Valley railway line. The second of two planned six-week line closures is set to begin this Saturday, 19th July, meaning no rail services will run between Caerphilly and Rhymney until 31st August.
Since construction on the upper Rhymney line commenced in March 2025, teams have successfully upgraded over 15 kilometres of railway track. A crucial milestone was reached in June with the completion of all 693 planned foundations between Caerphilly and Rhymney. These foundations are essential to support the Overhead Line Equipment (OLE) that will power the new electric trains. To date, 466 steel posts have been installed to hold the overhead wires in place, representing approximately 55% of the total posts required along the line.
The previous six-week closure of the upper Rhymney line in April proved highly effective, allowing teams increased access to the railway to carry out these vital upgrades more efficiently. Earlier, in late 2024, ground investigations on the Rhymney line initially faced a 50% refusal rate for the remaining 333 foundations, meaning half could not be completed in a single attempt. This would have led to costly return visits and increased disruption for local residents.
However, enhanced access to the line during the railway closures enabled teams to conduct thorough foundation probing. This process involves checking the level of bedrock, which informs adjustments to the approach or design for the OLE system. By adapting piling methods to suit the bedrock conditions, the refusal rate dramatically dropped from 50% to just 0.3%, with only 10 refusals out of the 333 foundations.
A further benefit of the extended line closures is that the majority of the noisy piling work has been conducted during daytime hours, significantly reducing the impact of this major infrastructure project on nearby residents.
To allow teams to continue their work installing OLE and electrifying the Upper Rhymney line, the section between Caerphilly and Rhymney will close from Saturday, 19th July to Sunday, 31st August. Rail replacement services will be in operation, with the exception of Friday, 1st August, when the line will re-open to accommodate the Catfish And The Bottlemen concert at the Principality Stadium.
TfW encourages all passengers travelling on the Rhymney line to check before they travel. While acknowledging that these closures directly affect local communities, TfW highlights that the ongoing upgrades are crucial for the introduction of brand-new tri-mode trains (Class 756s) to the line, promising faster, greener, and more accessible transport for the communities of South Wales.
