Passengers are being reminded about railway line closures between Barnham, Chichester and Havant starting in four weeks.
Network Rail will shut the line over nine days during the autumn half-term, as well as two Sundays and a further weekend to allow for 2.3km of new track to be laid and improvement works at several level crossings.
During the weekdays, from Monday October 28 to Friday November 1, buses will replace trains between Havant and Chichester and journeys will take longer than usual.
On the weekend dates the line between Havant and Barnham will be closed, meaning buses will replace trains between those stations on each date affected.
Work on the level crossings will result in some diversions on local roads.
Throughout the work there will be no Southern trains west of Havant to Portsmouth or Southampton. Great Western Railway services to/from Brighton will run to/from Portsmouth instead.
Trains to London will still run from Havant (to London Waterloo via South Western Railway) and Bognor Regis (via Southern).
During the weekdays, trains to London will also run from Chichester (via Southern).
Paul Harwood, investment director for Network Rail Southern, said: “Our information campaign has been underway for several weeks, but we will be stepping this up even more between now and the closure dates. We want to ensure that passengers are aware of the work and of the alternative transport arrangements which will be in place.”
He added: “We are working closely with the train operators, local councils and businesses to ensure that people are aware of the work and of the alternative transport arrangements which will be in place.
“Opting for this closure is the most efficient and least disruptive approach. The alternative would be many weekends of disruption. Once complete the work will improve the reliability of rail services on the line reducing delays for passengers.”
Keith Jipps, infrastructure director at Southern’s parent company Govia Thameslink Railway, said: “Our Southern services will be significantly affected by this vital work to improve reliability and passengers should check ahead and allow longer for their journeys.”
The planned dates for work are: Nine days from Saturday October 26 to Sunday November 3 inclusive, Sunday November 10, Sunday November 17, Saturday November 30 and Sunday December 1.