The work will cover a ten mile stretch of the line to remove, clean and replace ballast.
Network Rail aims to complete the work over an 18-week period – ending in August – however requires changes to the late evening Southern services to do so.
The changes will take place Monday to Thursday evenings from April 4 until August 22.
There will be a two week break from Monday June 6 where no changes will be made to the services.
The changes will be:
The 21.32pm Victoria to Portsmouth and Southsea service will be diverted after Three Bridges, calling at Haywards Heath, Ford, then as timetabled.
The 21.40pm Portsmouth Harbour to Three Bridges service will be diverted after Ford calling at Haywards Heath and Three Bridges.
The 22.32pm Victoria to Chichester service will terminate at Horsham.
The 22.40pm Chichester to Three Bridges service will not run.
An additional train service will run as follows:
00.09am Horsham to Three Bridges calling at Littlehaven, Ifield, Crawley and Three Bridges.
Replacement bus services will run as follows:
22.59pm and 23.39 Horsham to Chichester calling at Christ’s Hospital, Billingshurst, Pulborough, Amberley, Arundel, Ford, Barnham and Chichester.
23.00pm and 23.40pm Horsham to Bognor Regis calling at Christ’s Hospital, Billingshurst, Pulborough, Amberley, Arundel, Littlehampton and Bognor Regis.
01.02am Chichester to Portsmouth & Southsea calling at Fishbourne (A259), Bosham, Nutbourne (A259), Southbourne (A259), Emsworth, Warblington, Havant, Fratton (Goldsmith Avenue) and Portsmouth & Southsea.
22.26pm Barnham to Horsham calling at Arundel, Amberley, Pulborough, Billingshurst, Christ’s Hospital and Horsham.
22.57pm Barnham to Three Bridges calling at Arundel, Amberley, Pulborough, Billingshurst, Christ’s Hospital, Horsham, Littlehaven, Ifield, Crawley and Three Bridges.
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