Transport for Wales (TfW) has officially completed the full electrification of the Core Valley Lines (CVL), marking a major milestone in the delivery of the South Wales Metro and one of Wales’ most ambitious rail infrastructure transformations to date.
The final piece of Overhead Line Equipment (OLE) — an 800‑metre section between Cardiff Queen Street and Cardiff Bay — has now been installed and tested. This achievement moves TfW closer to full electrification across the 170 km network, concluding a six‑year programme launched in 2020.
Dubbed the “Welsh Tube”, the £1 billion CVL upgrade has already introduced electric tri‑mode trains to the South Wales Valleys in 2024. This spring, TfW will debut the first of 36 fully electric Class 398 tram‑trains, initially operating between Pontypridd and Cardiff Bay. These new units will support cleaner, more frequent, and more punctual services across the South Wales Metro.
Over the past six months, passengers have already benefited from improved reliability, with the Core Valley Lines becoming one of the most punctual networks in Great Britain.
Engineering at Unprecedented Scale
Since 2020, TfW and delivery partners have executed a vast engineering programme, including:
- 281.5 miles of overhead wiring
- Over 3,100 steel posts and 8,200 supporting components
- 14 track lowerings to accommodate wiring beneath bridges
- Five new substations
- Extensive vegetation clearance and new security fencing to reduce trespass risks
Working alongside Amey Infrastructure Wales, TfW deployed a world-leading Smart Electrification System, integrating wired and wire-free infrastructure. This innovation, enabled by tri‑mode and bi‑mode trains, allows seamless switching between overhead power and battery — cutting carbon, reducing cost, and avoiding lengthy disruptions typically associated with bridge reconstruction.
Government and Industry Praises
Cabinet Secretary for Transport and North Wales, Ken Skates, emphasised the significance of the achievement:
“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.
TfW’s Chief Infrastructure Officer, Dan Tipper, also praised teams across the project:
“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.”
Safety Reminder as Electrification Goes Live
TfW is urging residents and passengers to stay vigilant around the now‑energised infrastructure and to report any concerns by texting 61016.
The Bay Line transformation — part of the broader CVL programme — is part‑funded by the European Regional Development Fund through the Welsh Government.
Image credit: Transport for Wales
