Train passengers are reminded there will be no trains today (June 21) on the Uckfield Line.
Services have been withdrawn because of a strike by conductor members of the RMT Union.
Parts of the Southern network will see some services but the rail operator is warning about crowded trains, queuing systems at stations and no guarantees there will be trains to get passengers home.
It is the latest stage of an increasingly bitter dispute over the future role of conductors.
This is the fourth strike over the issue; previous ones were on April 26 and 27 and May 18.
It follows yesterday’s news that Southern’s poor performance is to be examined by a committee of MPs.
Southern is also suffering from a high level of staff sickness meaning many trains are cancelled at short notice.
The perennial problem of late running on the Uckfield Line continues.
For example, the service due into Uckfield last night at 8.22pm arrived 13 minutes late.
Brighton and Hove Buses will not be accepting Southern tickets during today’s strike.