Up to 35 staff who work for a speed-camera operator have voted to go on strike.
SIPTU members employed by GoSafe Ireland were balloted because of serious concerns over working conditions.
Their union also claims the company hasn't implemented a Labour Court recommendation over union recognition.
SIPTU organiser, Brendan Carr, said in a statement: “Our members were left with no option other than to vote for industrial action due to the continued refusal of the company to implement a Labour Court recommendation which confirms that it is SIPTU representatives who have the sole right to negotiate on behalf of its members with management.
“Our members have serious concerns relating to working conditions at the company. The employees of GoSafe were frustrated in their attempts to negotiate with their employer as it refused to attend the conciliation services of the State.
“This dispute highlights the unacceptable practice of Government Departments issuing contracts for state services to companies who refuse to engage with the industrial relations bodies of the State.
“This is a completely unacceptable situation when such companies are in receipt of large amounts of public funds.”
He added: “SIPTU wrote to the Minister for Justice and Equality, Charlie Flanagan, in relation to our members’ concerns.
“Union representatives asked to meet with the Minister to discuss this dispute and seek his assistance in resolving it prior to any industrial action, which could impact on the operation of measures to ensure road safety.
“Unfortunately, the Minister declined to intervene, despite the possible serious implications on road safety which is one of his key responsibilities.”
