Passengers planning to use the railway in May are advised to check before they travel ahead of a series of engineering works throughout the month.
Works will take place at various times in Bristol, Wiltshire, Thames Valley and in West London with services disrupted and buses replacing trains on some routes.
On three consecutive Sundays, May 8, 15 and 22, the line between Bristol Temple Meads and Bristol Parkway will be blocked with the Severn Beach branch line also closed. On the affected days rail replacement bus services will be running from Patchway, Bristol Parkway and Bristol Temple Meads, also covering Stapleton Road and Lawrence Hill.
In Wiltshire the Great Western main line will be closed near Royal Wootton Bassett from Saturday 27 May to Tuesday 30 May. This will impact services from Swindon to Chippenham and Swindon to Bristol Parkway with replacement bus services in operation. The same section of the railway will also be closed on June 10 and 11.
On those same weekends bridge work will also be carried out at Stratton St Margaret, Swindon, which means Ermin Road will be closed to traffic on both weekends.
In the Thames Valley and West London area no trains will stop at Taplow, Burnham, Hanwell or West Ealing from Saturday 29 April to Tuesday 2 May.
Lucy Elston, scheme project manager for Network Rail, said: “We would like to thank passengers and the local community for bearing with us while we carry out these works to Brunel’s railway.”
