Weekend strikes by railway staff could carry on until Christmas, operator Northern has admitted.
The company's services have been running on a reduced timetable every Saturday since September because of industrial action being taken by the RMT union.
Workers are at loggerheads with Northern bosses over plans to remove guards from trains.
Passengers were already facing disruption this weekend and next because of the row, with Northern admitting last month that there was "no end in sight" to the strikes because the company and unions were no longer talking.
And at a meeting in Wakefield on Thursday, the operator's stakeholder manager Pete Myers said the situation remained unchanged.
On Friday, the RMT confirmed they have now instructed members not to take on shifts on November 17 and 24 and December 1, 8 and 15.
Speaking to passenger representatives from across the Wakefield district, Mr Myers said: "I genuinely apologise to customers because I know they're facing disruption.
"At the same time I know they don't want to hear me apologise, they just want their service back.
"It's bad news for commuters and bad news for the economy of the north, which really has suffered as a result of the problems this year.
"About a month ago I'd have been more optimistic and said we were in a good position. But then the goalposts shifted.
"The RMT can call strikes at two weeks' notice. The rumour mill has it that it could carry on until Christmas. So that's where we are."
Both sides have confirmed that negotiations have broken down.
In a statement, RMT general secretary Mick Cash urged Northern to return to the table.
He said: "RMT continues to make every effort to get serious and meaningful talks going with Northern, but the company are not interested and would prefer to continue to bury their heads in the sand regardless of the impact on the travelling public.
“German-owned Northern Rail want to run nearly 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 secured agreements on other English franchises that enshrine the guard guarantee. Similar agreements have also been reached in Wales and Scotland.
"Arriva Rail North need to do the right thing and come to an agreement that secures a guard on their trains too.
“We thank the public for their support and understanding throughout this dispute over rail safety and access and the union remains ready for genuine and serious talks.”