Train passengers across the north of England are to be hit by strike action on two services at the same time, the RMT union has said.
Workers on Virgin Trains East Coast and Arriva's Northern service plan to strike on 28 April in a row about the role of on-board staff.
The Virgin stoppage will continue on 29 April but the firm said it planned a "near-normal" timetable.
The RMT wanted "explicit clarification" on the future role of guards, it said.
The union is also in a long-running dispute with Southern and Merseyrail over staffing and the same issue of who opens and closes train doors.
Staff at those companies are not striking on the same days.
Virgin, which runs trains on the east coast route between London, north-east England and Scotland, said there would be no driver-only trains and changes to staff roles would have a "zero impact on safety".
The train manager now carries out duties previously undertaken by guards as well as supervising on-board catering staff, the company said.
But the RMT accused Virgin of implementing changes without a formal agreement.
RMT general secretary Mick Cash said it was "simply appalling" Virgin had "refused to give basic assurances on the safety-critical role of the guard".
A union statement said the company had only repeated "the vague and non-committal mantra of 'within our discussions we have confirmed that the safety-critical duties of the guard will remain on the train'".
"This mealy-mouthed form of words gives no reassurance to RMT members," it said.
Northern's deputy managing director Richard Allan said it was "very disappointed".
"There is a lot to discuss and we urge RMT to get back round the table with an open mind as soon as possible," he said.
"In addition to protecting jobs and current pay, we are also willing to offer future, annual pay reviews for existing conductors if we can agree a deal with RMT."
Virgin Trains East Coast managing director David Horne said the strike was "pointless" as the company had guaranteed "no compulsory redundancies, no impact on safety and a near normal timetable in place during the walk-outs".
"Last week - the first full week since the changes - saw us achieve our second highest customer satisfaction score since taking over the franchise, so we are confident the changes are benefitting customers," he said.
The passenger group Transport Focus said it was "extremely disappointing" the strikes were spreading.
Director David Sidebottom said: "It is particularly uncaring to organise strikes on the May Bank Holiday weekend when many people make special journeys for holidays or to see friends and family."