Commuters are facing disruption next week after union bosses announced two further days of rail strike action.
The RMT Union said today (Tuesday) that its members will walk out for 24 hours on Monday and next Thursday, March 29.
Northern, run by Arriva Rail North, operates train services across Yorkshire, including in Leeds, Halifax and Wakefield.
It comes after talks broke down between the union and Northern Rail, in a dispute over driver-only operated trains.
RMT General Secretary Mick Cash said: “Every single effort that RMT has made to reach a negotiated settlement with Northern Rail over safe operation and safe staffing has been kicked back in our faces.
"No one should be in any doubt, this dispute is about putting the safety of the travelling public before the profits of the private train companies."
The strikes will be the latest in a series by members of the union over long-running disputes dating back more than 12 months.