Work between Llangadog and Llanwrda will disrupt rail services along the Heart of Wales line later this month.

Network Rail will carry out essential engineering work on the Glantowy Viaduct, affecting train journeys for 11 days from Thursday, November 21 to Sunday, December 1.

During this period, buses will replace trains between Swansea and Llandrindod stations.

The work will involve renewing the bridge deck on the viaduct, including changing 19 pairs of timbers, which were last fully replaced in 1990.

Engineers will also carry out steelwork repairs to the structure holding the timbers in place.

Additionally, 60 new sleepers will be installed, more than 200 metres of track will be re-railed, and 400 tonnes of ballast (track stone) will be replaced.

While the line is closed, engineers will also relay switches and crossings 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.