With just days to go before the Rugby League World Cup First Great Western is advising customers to check before they travel, as Network Rail carry out essential engineering work in the Severn Tunnel.
The railway between Bristol and Newport will be closed on Saturday 26 October and Sunday 27 October for the works.
Trains from London will be diverted between Swindon and Newport towards Cardiff and journey times will be extended by up to an hour.
Rail replacement bus services will be in operation between Bristol Parkway and Newport.
Services between Bristol and South Wales
Trains between the South West, South Coast and Bristol Temple Meads to and from Cardiff Central will start and terminate at Bristol Parkway for bus connections.
Travelling to and from Bristol Parkway
A limited number of services will link London Paddington and Bristol Parkway. Frequent connections are also available from Bristol Temple Meads to Bristol Parkway. From South Wales change at Newport for bus services.
Travelling to and from Patchway and Pilning
Rail replacement bus services will link these stations with Severn Tunnel Junction and Bristol Parkway for onward train connections.