The last 800m of overhead has been energised and tested between Cardiff Queen Street and Cardiff Bay, completing the six-year £1 billion project to electrify the Core Valley lines, which cover 170km.

Tram trains are now set to start entering service between between Pontypridd and Cardiff Bay.

Transport for Wales said more than 3,100 steel posts and five substations have been installed, and the track has been lowered under 14 bridges to create room for the OHLE.

The network has been partially electrified so that it can be used by bi- and tri-mode trains.

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 £1 billion 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. This is another significant milestone on our mission to transform our railways.’

TfW chief infrastructure officer Dan Tipper added: ‘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.’

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