More than 100 workers at KiwiRail's Hillside workshop in Dunedin have passed a motion of no confidence in their managers.
Members of the Rail and Maritime Transport Union held a stopwork meeting on Wednesday morning to protest against the growing use of contractors and overtime only three months after the company made 44 workers redundant.
KiwiRail says the work was unexpected and will only last a few months.
The workers have condemned the actions of the Hillside site manager and the national workshops manager and called for KiwiRail chief executive Jim Quinn to step in to resolve the conflict.
Union general secretary Wayne Butson says the workers are angry there appears to be no longterm plan or vision for the Hillside workshop.
Mr Butson says the motion shows how bad the situation has become, as in his experience a no-confidence motion in management is a rare step.
He says union attempts to rebuild the relationship with KiwiRail's management are failing.