If the strike takes place it will affect Southern services across Sussex, with no service on many routes and only a limited service between approximately 7.30am and 6pm, according to Southern Railway.
Southern said it will extend the service hours if able to, but for commuters travelling from London to stations between Crawley and Chichester, Hove and Bognor Regis, or between Brighton and Eastbourne, the last connecting train may be as early as 4.30pm.
Queuing systems will be in place at many stations, but the railway company said they could not guarantee to get everyone to their destination.
Cycles will not be permitted on Southern, Gatwick Express or Thameslink trains (south of Blackfriars) on the date affected.
Gatwick Express and Thameslink services will be largely unaffected by the strike but some services are expected to be extremely busy on these days.
For live running information, including live departure boards and service alerts, visit the live running page here.
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