Passengers are urged to check before they travel between Swansea and Llandrindod later this month, when Network Rail will be carrying out essential engineering work at a viaduct on the Heart of Wales Line.

Buses will replace trains between Swansea and Llandrindod stations from Thursday, November 21 to Sunday, December 1 inclusive.

Network Rail engineers will be renewing the bridge deck on Glantowy Viaduct, between Llangadog and Llanwrda stations in Carmarthenshire.

They will change 19 pairs of timbers - which were last fully replaced in 1990 - as well as carry out steelwork repairs to the structure holding the timbers in place.

They will also install 60 new sleepers and re-rail more than 200 metres of track, replacing 400 tonnes of ballast (track stone) in the process.

While the line is closed, engineers will also relay switches and crosses (moveable sections of track that guide trains from one track to another and allow them to cross paths) and points (the mechanical systems that move the switches and crosses) near Pontarddulais.

Rachel Heath, Network Rail Wales and Borders operations director, said: “Our teams will be working around the clock to carry out important renewals on the Heart of Wales Line.

“We recognise there is never a good time to close the railway for a period of 11 days. But, by completing this work in one stint, we will minimise wider disruption – and do the work in a more cost-effective way – than if we had to return over several weekend shifts.

“I would like to thank passengers for their patience and understanding, and urge them to check their journeys before travelling.”

Transport for Wales (TfW) rail replacement services will call at all stops between Swansea and Llandrindod. A quicker service calling at a limited number of key stations will also be available. 

Due to the additional time needed for road transport, the timetable will differ from the current rail timetable. 

Details are available in journey planners on the Transport for Wales website and passengers are strongly advised to check for the latest information before travelling.