Drivers at Dublin Bus represented by Siptu have voted overwhelmingly for industrial action as part of their ongoing pay dispute.
They voted by a majority of 95% for industrial and strike action, while Siptu clerical members also voted to support industrial action and strike action by 87% and 80%, respectively.
It follows their rejection of a recent Labour Court recommendation on pay at Dublin Bus.
All unions at the company submitted a pay claim of 15% over three years starting from January 2016, and agreed to seek a retrospective pay increase in lieu of the 6% from a previous national pay agreement that was deferred.
Improvements such as maintaining the link between pay and pensions and making shift pay reckonable for pension purposes in line with sister company, Irish Rail, are also being sought.
There are ballots by five other grades ongoing which will be completed by Tuesday, August 16.
Siptu Divisional Organiser for Transport, Energy, Aviation and Construction, Owen Reidy, said: "This result today demonstrates the determination of members to bring this pay dispute to a fair conclusion.
"Drivers and other workers at the company have not had a pay increase for eight years, have suffered reductions in earnings over the recessionary period and have been through three comprehensive restructurings during that time..
Mr Reidy claimed that Dublin Bus had started to make a profit again from November 2014 with passenger numbers and revenue increasing.
He said: "We are prepared to engage with the employer on issues of productivity in addition to a general wage round agreement.
We would urge Dublin Bus to return to the bargaining table immediately to reach a new agreement to avoid the very real prospect of 24- and 48-hour stoppages and perhaps an indefinite all out strike in Dublin Bus.
"We intend to meet with our members next week to discuss and plan a sustained campaign of action in order to reach a satisfactory outcome."