Train services around Aldershot and west Surrey will be cancelled on Sunday morning while maintenance work is carried out on a bridge by engineers.
South West Trains said trains on the lines between Farnham and Woking, and between Guildford and Ascot via Aldershot, would be closed from 1.15am until 1pm on Sunday (January 5).
Hourly bus services will replace the cancelled services, however the operator has warned that the buses may themselves be delayed due to flooding on roads. The affected bridge is in Government Road, near to Aldershot railway station.
A spokesman for the South West Trains-Network Rail Alliance said: "A programme of routine bridge checks is currently taking place and, during a planned inspection prior to Christmas, our engineers identified that some work was needed to repair defects to the bridge near Aldershot station."
He said the first major stage of the work was completed on New Year's Day.
All lines between Guildford and Ascot were closed on Friday, with fallen trees blocking lines blamed for the disruption, which was expected to continue until 2am on Saturday.
As well as Aldershot, these closures affect trains travelling through stations in Ash, Ash Vale, Frimley, Camberley and Bagshot.
Buses will replace trains between Farnham and Farnborough to connect with trains to and from Woking and London, and also between Guildford and Ascot, stopping at all stations on the line.
A shuttle train will run between Farnham and Alton, calling at Bentley.
Valid train tickets will be accepted for the bus journeys.
If the necessary work is completed on time, the operator expects all services to be back to normal from 1pm on Sunday.