100% electrification of the Core Valley lines complete

Transport for Wales (TfW) has completed the full electrification of the Core Valley lines as part of the billion pound South Wales Metro project.

The overhead line equipment (OLE) on the final 800 metre section between Cardiff Queen Street and Cardiff Bay has now been completed and tested as TfW prepares for the full electrification of the 170km network.

It completes one of Wales’ most ambitious rail infrastructure transport projects.

Dubbed the ‘Welsh Tube’, the £1bn, six-year scheme began in 2020 and brought electric tri-mode trains to the South Wales Valleys for the very first time in 2024.

This spring, TfW will introduce the first of its 36 fully electric Class 398 tram-trains.

The new fleet will initially operate between Pontypridd and Cardiff Bay, providing greener, more frequent services as part of the South Wales Metro.

TfW says the improvements have seen the Core Valley lines become one of the most punctual and reliable networks in Great Britain over the past 6 months.

Since work began, TfW and its partners have delivered an intensive programme of specialist engineering which included, 281.5 miles of overhead wires, and over 3,100 steel posts and 8,200 small steel parts installed to hold the wires in place.

14 railway track lowers were completed to install wires under bridges and five substations were installed.

Extensive vegetation clearance and fencing renewals were carried out to keep the network safe from trespass.

Working closely with partners Amey Infrastructure Wales, TfW introduced a world-leading Smart Electrification System that combined wired and wire-free sections.

Innovative

This was made possible by innovative tri and bi-mode trains, capable of switching seamlessly between overhead electric power and battery.

TfW says this approach has delivered carbon and cost reductions compared with traditional fully wired systems, while avoiding the need for lengthy and disruptive bridge closures.

Cabinet Secretary for Transport and North Wales, Ken Skates said: “This is a landmark moment for rail in South Wales.

“We are finally seeing our ambition become a reality thanks to our unprecedented investment of more than £1bn to transform the CVL, with £800 million on new trains, and years of hard work and commitment from TfW.

“New, faster, modern trains, offering increased capacity and more frequent services helping to transform passenger experiences.

“This is another significant milestone on our mission to transform our railways.”

‘Landmark’

Dan Tipper, Chief Infrastructure Officer at Transport for Wales, said: “Completing the electrification of the Core Valley Lines is a landmark achievement for our infrastructure teams and construction partners.

“This has been one of the most complex engineering programmes undertaken in Wales in recent decades and delivering it safely and efficiently is a testament to the skill and dedication of everyone involved.

“I’m immensely proud of the work delivered and the benefits it will unlock for passengers across the Valleys, with greener and faster services connecting communities.

“We’re hugely grateful to our communities who have at times been heavily impacted by the work. They will now be able to reap the benefits of the improvements through faster, greener, more frequent and reliable services.”

With the network electrified and live, TfW is reminding communities of the dangers of trespassing near the railway and urges passengers and residents to stay alert and report any concerns by texting 61016.

Timeline

The Bay line transformation project, part of the wider Core Valley Lines transformation for the Metro, has been part-funded by the European Regional Development Fund through the Welsh Government.

In 2020, work began to install Overhead Line Equipment (OLE) across the Core Valley Lines and in 2023, the first lines were electrified through Aberdare, Merthyr, and Pontypridd to Cardiff.

In early 2024, the Treherbert line was electrified following nine months of extensive engineering works.

Following this, the Coryton and Rhymney lines were electrified in 2025, marking 99% of the CVL network electrified.

In 2026, the Cardiff Bay section tested in preparation for 100% electrification of the CVL network.