The Rail and Maritime Transport Union says workers at KiwiRail's Hillside workshop in Dunedin will hold a stopwork meeting on Wednesday morning.
The Hillside workers are objecting to the state-owned enterprise offering them overtime and using contractors for urgent wagon maintenance just three months after making 44 people redundant from the site.
Kiwirail says the work was unexpected and will only last a few months.
The union's South Island organiser, John Kerr, says site delegates have decided their 110 members need to discuss the situation.
Mr Kerr says the company has agreed to the stopwork meeting.
He says union representatives expect to meet Kiwirail management on Thursday.