The National Bus and Rail Union is rallying its members ahead of next week's all out strike.
Staff are set to walk off the job from Monday over a €12m cost cutting plan.
The company says it has to implement tough measures or Bus Eireann could go bust by May.
The NBRU says the dispute is so complex, it would be almost impossible to find a resolution between now and Sunday night.
It's advised its members to prepare for the "mother of all transport dispputes."
It's feared Dublin could be badly hit by Monday's action because there'll be workers taking to the picket lines at depots they share with Dublin Bus and Irish Rail.