SIPTU members at Irish Rail have voted for industrial action if management presses ahead with cost-cutting plans. Members have balloted by a ratio of 2-to-1 to support of official action.
The union says it would call a one-day work stoppage.
SIPTU members had recently voted by 51% to 49% against a Labour Court recommendation which involved pay cuts, redundancies and restructuring at the company.
In a ballot counted today, members voted by 66% to 34% in favour of industrial action - but also voted 64% to 36% against strike action.
According to SIPTU Organiser, Paul Cullen, industrial action will only occur if management "acts provocatively" by changing members' conditions of employment without agreement.
But he says the action would be a 24-hour strike.
Irish Rail management is considering the SIPTU initiative and has confirmed that it will respond shortly to the proposal.