It's over a row about driver-only operated trains.
Up to 60% of services could be cancelled as members of the RMT union strike from Saturday to Monday.
Mersey Rail workers are also striking on Saturday and Monday.
Northern will run revised train timetables
People are being warned to give themselves extra time to travel.
Revised Northern services on Saturday and Monday will generally run between 7am and 7pm but will only operate between 9am and 5pm on Sunday.
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