Transport for Wales accelerates Rhymney Line electrification ahead of summer rail closures
Transport for Wales accelerates Rhymney Line electrification ahead of summer rail closures
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Transport for Wales (TfW) is making significant headway on its ambitious programme to transform and electrify the Rhymney Valley railway line, with major progress reported ahead of a planned six-week line closure beginning Saturday 19 July.
The closure, which will run until Sunday 31 August, is the second in an intensive eight-month schedule to modernise the Upper Rhymney line. During this period, no rail services will operate between Caerphilly and Rhymney, though rail replacement services will be provided. A special one-day reopening is scheduled for Friday 1 August to accommodate concert-goers attending the Catfish and the Bottlemen performance at the Principality Stadium in Cardiff.
The upgrade project, which began in March 2025, is part of TfW’s broader commitment to delivering faster, more sustainable, and more accessible rail services across South Wales.
Since construction began, more than 15 kilometres of railway track have been upgraded. A major milestone was achieved in June with the completion of all 693 planned foundations between Caerphilly and Rhymney. These foundations are critical to supporting Overhead Line Equipment (OLE) that will power TfW’s new Class 756 tri-mode trains—capable of running on diesel, battery, or electric power.
To date, 466 steel posts have been installed to hold the overhead wires in place—representing roughly 55% of the total needed for the full electrification of the route.
The first six-week closure, which took place in April, allowed engineers extended and efficient access to the railway, significantly improving progress. Ground investigations on the Rhymney line in late 2024 initially revealed a 50% refusal rate when attempting to install foundations—indicating half could not be completed in one visit due to challenging bedrock conditions.
Thanks to the extended closure and improved access, teams were able to carry out foundation probing to assess bedrock depth and stability. This allowed TfW to adapt piling methods in real time, resulting in a dramatic reduction in the refusal rate from 50% to just 0.3%—equating to only 10 refusals out of 333 foundations.
“This smarter approach not only improves efficiency but also prevents costly return visits and reduces disruption to local communities,” a TfW spokesperson said.
The extended access to the railway has also allowed TfW to schedule most noisy piling work during daytime hours, reducing disturbance for residents living along the line. TfW has emphasised its commitment to engaging with the community throughout the project and mitigating disruption wherever possible.
While the upcoming line closure will inconvenience regular commuters and residents, TfW says the long-term benefits are clear. Once completed, the Rhymney line will be able to accommodate the Class 756 tri-mode trains, delivering faster journey times, reduced emissions, and improved accessibility.
“These upgrades are a critical step in modernising our rail network and delivering a greener transport future for South Wales,” said the TfW spokesperson. “We acknowledge the inconvenience of temporary closures, but the result will be a more reliable and environmentally sustainable service for decades to come.”
What Passengers Need to Know:
- Closure Dates: Saturday 19 July – Sunday 31 August
- Affected Route: No services between Caerphilly and Rhymney
- Replacement Services: Bus services will be in place
- Temporary Reopening: Friday 1 August for the Catfish and the Bottlemen concert
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