Southern Railway workers are to stage 14 days of strike action in five blocks from next month in the long running dispute over the role of conductors.
The Rail, Maritime and Transport union announced an escalation of industrial action which will bring fresh travel chaos for hundreds of thousands of passengers.
The strikes will start on October 11 and will be held intermittently until December 8.
The union has held a series of walkouts in recent months in protest against changes to the role of conductors at Southern, which is owned by Govia Thameslink Railway.
Conductors are to take strike action by not booking on for any shifts between:
• 00.01 on Tuesday 11th October and 23.59 on Thursday 13th October
• 00.01 on Tuesday 18th October and 23.59 on Thursday 20th October
• 00.01 on Thursday 3rd November and 23.59 on Saturday 5th November
• 00.01 on Tuesday 22nd November and 23.59 on Wednesday 23rd November
• 00.01 on Tuesday 6th December and 23.59 on Thursday 8th December.
RMT General Secretary Mick Cash said in a statement: “Yet again our members are being forced to take industrial action in a bid to maintain a safe and secure service on Southern.
“Govia Thameslink and the government have made it clear that they have no interest in resolving this dispute.
“Instead they have begun the process of bulldozing through the drive towards wholesale Driver Only Operation (DOO) without agreement and without any concern for the impact on safety, security and disability access.
“Last week there was a train derailment near Watford that involved two trains.
“The guards on both trains played a vital role in protecting the passengers and the trains in what were extremely frightening circumstances.
“If the train had been DOO and without a guard the consequences would have been far worse.
“This week we reached a deal with Scotrail that we are recommending for acceptance in a referendum of our members, that guarantees a fully competent conductor/guard on every new train.
“This agreement protects passengers, and guarantees a second safety trained member of staff on board a train, who can assist if there is an incident such as we recently saw near Watford.
“If an agreement can be reached on Scotrail, then an agreement can also be made on Southern.
“In the light of these recent developments it is disgraceful that neither the company or the Government are prepared to engage and are continuing to attempt to impose DOO in the interests of putting profit before safety.
“We call on them to get round the negotiating table as an urgent priority.”
GTR’s Passenger Services Director Angie Doll said in a statement: “The RMT’s desire to heap yet further travel misery on the public and affect the everyday lives of so many people is shameful.