Rail operator Govia Thameslink Railway has been locked in a bitter dispute with the RMT union for months over planned changes to the role of conductors, with drivers operating train doors instead.
The union has already held four walkouts already in 2016, with a two-day strike set to begin on Wednesday September 7.
According to Southern it will only be able to run 65 per cent of services against the revised timetable introduced in July through the use of contingency conductors.
Many routes will have fewer trains, while others will have none at all, with many parts of the network seeing trains start late and finish early.
If the strike goes ahead, no trains are set to run between Horsham and Dorking, Havant and Chichester, Uckfield and Hurst Green, and between Eastbourne and Hastings.
No trains will call at Plumpton or Cooksbridge, while a rail replacement bus service will operate between Seaford and Lewes.
Alex Foulds, passenger services director at Southern, said: “Passengers will be rightly dismayed that the RMT has chosen to disrupt services yet again.
“This two-day strike will achieve nothing. After many months of trying to reach agreement with the RMT, we are now moving forward with our plans for the benefit of customers and we urge the RMT to join us in putting passengers first.
“We have guaranteed all our onboard staff a job until the end of the franchise, with no reduction in salary. Our plans are safe, and will mean fewer cancelled trains. We are sorry that our passengers will once again suffer because of RMT intransigence, and we urge the union to work with us to find a sensible way forward.”
Passengers can find out details of how they may be affected so they can plan their journeys at Southern’s website.
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