Bus and rail services will be severely disrupted by a strike that has been called for next Tuesday, Transport company Translink has said.
Thousands of commuters could be affected by the one-day action.
The unions said the action was because of plans to restrict the right of public service pension scheme members to retire on a full pension at 60.
Unison members and Nipsa members will also be on picket lines that day because of the proposed changes.
Lily Kerr of Unison said a strike could hit services hard, with non-teaching staff in schools and colleges joining in the action.
"Everybody will be out from the school cleaner, the officer cleaner, to the chief executive," she said.
Alan Mercer, Translink's Director of Human Resources, said they were disappointed the trade unions ATGWU, Amicus, TSSA and Siptu were taking the action.
"These proposed changes, have not yet even been subject to consultation in Northern Ireland," he said.
"The major impact will be to inconvenience passengers, especially the 65,000 school children we carry to and from school each day and those others who depend on us for travel to work, medical treatment, education and visiting friends and relatives."
This strike action is the result of the proposed abolishment of "rule of 85" by government.
This allows anyone with a local government pension retire at 60 with their accrued pension if their age plus years worked equals 85 or above.
The consultation to end "rule of 85" in Northern Ireland is not due to start until later in 2006.
Consultation in Great Britain has already finished, and industrial action is planned in protests across the UK on 28 March.
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