The RMT union has been fighting Govia Thameslink Railway over plans to introduce driver-only operation, which involves drivers opening and closing train doors.
It has held numerous strikes since April 2016 and its latest 24-hour walkout began today.
Currently train drivers’ union ASLEF has an overtime ban in place forcing some changes to the Southern timetable, while it is balloting its members on strike action.
According to Southern’s website: “The RMT union announced a 24-hour strike between 00:01 and 23:59 on Monday 10 July. We do not expect this to have any effect on our service and plan to operate the amended timetable on this date.”
Mick Cash, general secretary of the RMT, said: “It’s time for the rail companies and the Government to get out of the bunker and get talks on that address the fundamental issues of safety, accessibility and the guard guarantee.”
The union has raised concerns about the potential loss of a second safety-critical member of staff on Southern services.