Workers in one of the rail operators hit by disruption to services are to stage a series of fresh strikes in the long-running dispute over the role of guards.
Members of the Rail, Maritime and Transport union on Arriva Rail North will walk out for 24 hours on Tuesday, June 19, Thursday, June 21, and Saturday, June 23.
The action will hit the company's Northern Newcastle-Middlesbrough services passing through Sunderland, Seaham, Hartlepool, Seaton Carew and Billingham.
The company has been under fire in recent weeks because of daily delays and cancellations to rail services.
RMT general secretary Mick Cash said: "We have seen over the past fortnight that Northern is a company which has declared war on its passengers and staff alike.
"RMT will not stand aside while the threat to axe safety critical guards from Northern services remains central to the company plans.
"This company has reduced the timetable to total chaos and the union will not allow them to slash the safety culture to ribbons in the same fashion.
"It is a tribute to the determination and professionalism of RMT members on Arriva Rail North that they have remained rock solid for over a year now in what is a clear-cut battle to put public safety before private profit.
"German-owned Northern Rail want to run half a million trains a year without a safety critical guard on board in a move that would wreck both safety and access to services and they should listen to their front-line staff and pull back from that plan immediately."
Northern, as on previous strike days during the lengthy dispute, is expected to run a reduced timetable.
Deputy managing director Richard Allan said: "Northern is working extremely hard to stabilise and provide certainty in delivering a reliable train service on those parts of our network affected by recent very significant disruption and cancellations.
"We have apologised repeatedly and extensively to customers, are working urgently on our additional customer compensation offer, and our energy and focus is on providing a better service for customers.
"The May timetable problems and the latest RMT strike action will not deter us from delivering our modernisation plans for customers. £500 million of new trains which are currently under construction, better stations and more services by 2020.
"We are still prepared to guarantee jobs and pay reviews for conductors until the end of our franchise in 2025, with the Government guaranteeing jobs beyond that, but both guarantees depend on RMT ending its strike action."