SIPTU is calling on the Transport Minister Shane Ross to resolve a 72-hour strike by GoSafe speed van operators.
Safety chiefs insist speed-restrictions are being strictly enforced this bank holiday weekend despite the action.
A spokesperson for GoSafe said: “We have moved early to ensure disruption caused by SIPTU’s action will be minimised. Safety cameras will continue to be operational over the full weekend.”
The union's Brendan Carr said workers do not want to take action, but feel they have no other choice.
Mr Carr said: "It's the Minister who is responsible for road safety and the Gardaí who are responsible for road safety and both of those signed up to this contract with this company which clearly states that this company have to engage through the third-party mechanisms of the State.
"I'd ask the Minister to take his responsibility seriously and actually resolve this dispute and intervene to get this dispute resolved."