The South Wales Metro project is transforming train services in South Wales with one of the UK’s largest-ever upgrades of railway infrastructure.

The upgrade is being celebrated by Transport for Wales, in conjunction with the Campaign for Better Transport, to mark Better Transport Week 2026, which runs from Monday, 15th to Sunday, 21st June.

One of the lines to benefit is that to Treherbert, where what was once a historic valley line is now a modern electrified railway served by brand-new trains. Until early 2023, trains on the line were controlled by a Victorian-era token exchange system. Before entering single-track sections, drivers used to leave their cab to collect a physical token and return it at the other end of the single-track section. The system was effective, but not appropriate for a modern, high-frequency railway.

To upgrade the Treherbert line, it was closed for nine months for extensive engineering works, which included the installation of a modern digital signalling system that is controlled from a new £100 million depot and Control Centre at Taff’s Well.

For passengers, as well as a more frequent service by modern trains, contactless pay-as-you-go ticketing provides them with the best-value fares. Since being introduced, passengers tapping in and out have made over 4.5 million journeys across the South East Wales metro network.

Other lines in the area upgraded include the Core Valley Lines, which have been electrified, and allowed Transport for Wales to introduce brand-new Class 756 trains. Known colloquially as FLIRTS, which stands for Fast Light Intercity and Regional Trains, Class 756s started running on the lines in February 2025. The Class 756s are also tri-mode, which can use diesel or battery power on non-electrified sections of line.

“The Treherbert line is one of our biggest transformations as part of the South Wales Metro, and we’re pleased to welcome representatives from Campaign for Better Transport to Wales and offer them the opportunity to visit the line and experience the wider South Wales Metro. We’ve been on a journey of transformation with rail in Wales and have replaced some of the oldest railway infrastructure with some of the most modern in Europe. Through this investment, we’ve also been able to remove older trains from the network and introduce brand-new, modern fleets, alongside electrification and upgraded infrastructure.”

“Just a few years ago, ‘pacer’ trains were running on these lines; today, customers are benefiting from faster, more reliable and accessible services that are designed around their needs. This transformation is already making a real difference—improving journey times, increasing capacity, and providing a more comfortable and sustainable experience for the communities we serve. None of this would have been possible without the dedication, resilience and professionalism of our amazing teams and partners, who have worked tirelessly to deliver such a complex programme of change while keeping services running for our customers.”

Marie Daly, Chief Operating Officer, Transport for Wales