10 Dec 2025

Transport for Wales has now electrified 99% of the railway lines in South East Wales as part of the South Wales Metro.

Overhead wires across the Rhymney railway line were switched on this past weekend, signifying another major milestone for the project, as well as the recent official opening of the South Wales Metro depot at Taff’s Well by His Majesty King Charles.

Since 2023, the Rhymney, Treherbert, Aberdare, Merthyr, Coryton and Caerphilly railway lines have all been electrified, with the final section of railway along the Cardiff Bay line planned to go live from early 2026.

Dubbed the ‘Welsh Tube’, the one-billion-pound project brought electric train services to the South Wales Valleys for the very first time last year and fully electric tram-trains will be introduced next year, providing more rail services and more capacity.

Over 90% of trains running on the Core Valley Lines ran to time (within 3 minutes) in October 2025.

Ken Skates, Cabinet Secretary for Transport and North Wales said: “I am delighted that our investment of more than £1bn to deliver a metro system fit for the future has reached another significant milestone.

“Electrification of our core valleys lines is helping to create better access to jobs, healthcare, and education with brand new trains offering a faster, more reliable, greener and more accessible transport system.”

Julie James, Counsel General and Minister for Delivery in Welsh Government, on visiting the Rhymney railway line said: “This is a game changer for many valleys communities, improving connectivity and making it easier for people to get to where they need to go quicker and without any hassle.”

Dan Tipper, Chief Infrastructure Officer at Transport for Wales added: “The electrification of the Upper Rhymney railway line signifies another major milestone for the South Wales Metro and delivering real change for the people of South Wales. It means that we’ll be able to introduce our Class 756 tri-mode trains on services between Caerphilly and Rhymney from 2026.

“Our infrastructure teams have worked intensively for the past eight months installing 903 steel structures, supporting 33km of overhead wires and laying 30km of high-voltage cable. This is a huge achievement for our teams, who have worked throughout the day and night to deliver these improvements.

“We’ve already introduced the first electric trains to the region and will continue next year, with the introduction of our Class 398 tram-trains.”