Fresh strikes in the long-running dispute over the role of guards on trains will cause more disruption today and again on Saturday.
Members of the Rail, Maritime and Transport (RMT) union at Arriva Rail North (Northern Rail) will walk out for 24 hours on both days.
The row has been raging for over a year on Northern and two years on Southern, with three other train operators also involved in the same dispute - South Western Railway, Merseyrail and Greater Anglia.
Northern's services will be disrupted on both strike days.
RMT general secretary Mick Cash said: "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 battle to put public safety before private profit.
"The next phase of action on Thursday and Saturday goes ahead exactly as planned as the company refuse point blank to engage in talks.
"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.
"RMT has agreed arrangements in Wales and Scotland that enshrine the guard guarantee. If it's good enough for Wales and Scotland to have safe rail services, it should be good enough for the rest of Britain.
"We thank the public for their support and understanding throughout this dispute over rail safety and access, and the union remains ready for talks."
The company said in a message to passengers: "On Thursday, the majority of availabletrains will operate between 7am and 7pm as we focus on running as many trains as we can to get you into work and home again.
"On Saturday, most trains will run between 7am and 5pm as we work to get you to and from leisure destinations across the region.
"As the overall number of trains running will be reduced, we expect trains and any replacement buses we operate to be extremely busy. Please allow extra time for journeys, plan carefully and consider whether travel is necessary.
"During the RMT strike action, we expect all services to be busy, especially in the morning and evening peak periods, and advise you to allow extra time to travel."