Transformation work continues on the Rhymney line

Transport for Wales (TfW) has made significant progress on its intensive eight-month programme to transform and electrify the Rhymney Valley railway line, but warned commuters about a 12 day line closure later this month.

The second six-week railway line closure will start on Saturday 19 July, with no rail services running between Caerphilly and Rhymney until 31 August.

Since construction on the upper Rhymney line began in March 2025, teams have upgraded over 15 kilometres of railway track. A significant milestone was achieved in June when the last of the 693 planned foundations from Caerphilly to Rhymney was completed.

These foundations will 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, which is approximately 55% of the total number of posts that will be installed along the line.

The previous 6-week closure of the upper Rhymney line which took place in April has allowed teams to work more efficiently, with more access to the railway line to carry out these essential upgrades.

Extended closures

In late 2024, teams began ground investigations on the Rhymney line. Initially, they faced a refusal rate of 50% for the remaining 333 foundations, meaning that half of the foundations could not be completed in one go. This would have led to costly return visits and more disruptions for local residents.

However, increased access to the line during railway closures allowed teams to conduct foundation probing. This process checks the level of bedrock, which helps teams change their approach or design for the Overhead Line Equipment (OLE) system. Adjusting piling methods to suit the bedrock conditions has resulted in the refusal rate dropping from 50% to just 0.3%, with only 10 refusals out of the 333 foundations.

The extended closures on the line have also allowed most of the noisy piling work to take place during the daytime, which has significantly reduced the impact of this major infrastructure project on nearby residents.

Upcoming Six-Week Closure

To allow teams to progress with their work to install OLE and electrify the Upper Rhymney line, the line between Caerphilly and Rhymney will close from Saturday 19 July to Sunday 31 August.

Rail replacement services will be in operation, and the line will re-open to accommodate the Catfish And The Bottlemen concert in the Principality Stadium on Friday 01 August.

TfW encourages all passengers traveling on the Rhymney line to check before they travel. While TfW recognises that these closures directly affect local communities, the upgrades being carried out now will enable the introduction of brand-new tri-mode trains (Class 756s) to the line, offering faster, greener, and more accessible transport for the communities of South Wales.

More information on Rhymney line closures, rail replacement services and where to find local bus stops can be found on TfW’s website: Rhymney line transformation | Transport for Wales