Tens of thousands of train passengers are to face disruption to their journeys during a �130m engineering project that is set to start on Friday. Major work on signalling around Basingstoke will see lines at the Hampshire station closed to services.
Network Rail's project will last until 15 April and will see buses laid on and services across the South diverted.
A spokesman for South West Trains said the project would "result in a better, more reliable train service".
Buses will replace trains on routes to and from Basingstoke, between Andover and Winchfield, Andover and Farnborough/Woking, Winchester and Winchfield, Winchester and Farnborough/Woking and Winchester to Reading.
Delays of up to an hour are expected on the service running between Weymouth and London Waterloo, which will see trains diverted via, and stopping at, Fareham, Havant, Guildford and Clapham Junction.
Other routes will also be affected by delays and diversions and passengers are being urged to check journey details before travelling.