Transport for Wales (TfW) has switched on overhead wires along the Rhymney railway line, marking a key milestone in the electrification of the South Wales Valley lines. The move follows the completion of work on the 25km stretch between Caerphilly and Rhymney, with the final section to Cardiff Bay expected to be electrified in early 2026.

The electrification of the upper Rhymney line will allow TfW to introduce tri-mode trains, capable of operating on electric, diesel, or battery power, replacing the last of the older diesel trains currently in service. This development forms part of the wider South Wales Metro programme, designed to modernise rail services across the region.

Dan Tipper, Chief Infrastructure Officer at TfW, praised the efforts of the teams involved:

“The electrification of the Upper Rhymney line has been made possible by eight months of intensive work by our infrastructure teams, including installing 903 steel structures supporting over 33km of overhead wires and laying 30km of high-voltage cable. I’d like to thank our teams for working around the clock to achieve this major project milestone. We would also like to thank our local communities for their patience as this transformation work was carried out through the day and night, as well as during disruptive railway closures over the Easter and Summer holidays.”

TfW also issued a safety reminder, warning that trespassing on railway lines is illegal and extremely dangerous, particularly on electrified tracks carrying 25,000 volts. The operator continues to promote its No Second Chances campaign, educating young people about the risks of railway trespass. By the end of 2025, over 42,000 students are expected to have taken part in sessions delivered by education provider Bollo.

Image: Transport for Wales