Conductors on Southern Rail are set to stage three 24-hour strikes on 26 April, 10 May and 12 May - because control of doors has been handed to drivers.
They're set to walk out at 11:00 BST on all three days, it's been reported
They're protesting Southern Rail’s plans to introduce "Driver Only Operation" rules, giving conductors new “onboard supervisor roles”.
The RMT union said the new rules will "threaten jobs, conditions and public safety”.
Southern Railway’s parent company, Govia Thameslink Railway (GTR), argued drivers opening and closing train doors will help staff provide better service to passengers.
A total of 306 members of the union voted in favour of the strikes while 14 voted against. Some 320 voted to one for other forms of industrial action.
RMT general secretary Mick Cash said: “RMT, supported by our Aslef colleagues, is wholly opposed to the attack on the safety-critical conductor grades and the threat of Driver Only Operation.
"Our members on Southern GTR have given loyal and professional service to the company and are being rewarded by being forced into a new grade, having their role and responsibility reduced and their hard earned terms and conditions attacked."
In a statement, GTR hit back: “A strike would be unnecessary and damaging. The changes we are making to the conductor role mean there will be no job losses and no reduction in salary for any staff, while passengers will benefit from having more visible staff on trains.
“We are preparing contingency plans in case a strike does go ahead but in the meantime we urge the RMT to return to the negotiating table and discuss the changes to the conductor role we are seeking to make.”