It will closed on the following days:
February 9 to March 3.
March 23 & 24.
March 30 & 31.
April 6 & 7.
Between February 16 – 19 and several weekends up to May 2019, the lines will be closed between: Three Bridges and Brighton; and Three Bridges and Lewes.
A spokesman said: “This will mean significant changes to train services across the Southern, Gatwick Express and Thameslink networks and longer journey times for some passengers.
“No trains will run between Three Bridges and Brighton or between Three Bridges and Lewes on these dates.
“Brighton and stations to the west will have trains to and from London, but these will be diverted via Littlehampton and Horsham.
“There will be no direct trains to London from Lewes or Eastbourne between these dates.”