‘Welsh Tube’ milestone: nearly all South East Wales lines now electrified

Transport for Wales has now electrified almost the entire railway network in South East Wales, with the latest milestone achieved over the weekend as overhead wires on the Rhymney line were switched on. The announcement follows the recent official opening of the South Wales Metro depot at Taff’s Well by His Majesty King Charles.

Since 2023, electrification has been completed on the Rhymney, Treherbert, Aberdare, Merthyr, Coryton, and Caerphilly lines, with the final section along the Cardiff Bay line set to go live in early 2026.

The one-billion-pound South Wales Metro project, often referred to as the ‘Welsh Tube,’ introduced electric train services to the South Wales Valleys for the first time last year. Fully electric tram-trains will be added next year, providing more frequent services and increased capacity. In October 2025, over 90% of trains on the Core Valley Lines ran on time, within three minutes of schedule.

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, 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.”

Image: Transport for Wales