Unions have threatened possible industrial action at Bus Éireann if staff are not given a pay rise.
Talks between management and unions, which took place at the Workplace Relations Commission over staff demands for increases, have been adjourned until 1 October.
Union sources said some progress had been made in the talks, and that management had accepted that a pay rise was warranted.
However, they cautioned that the two sides were "somewhat apart" on how the increase should be funded.
Unions are understood to be holding to their position that an initial increase should be a flat increase without productivity concession.
However, the union sources said that is that were secured they would be open to what they called "structural changes".
Last year, unions at Bus Éireann went on strike for three weeks, as the company sought pay cuts and redundancies in order to avert threatened insolvency at the State bus company.
A survival plan was agreed to resolve the dispute.
However, arriving for today's talks, National Bus and Rail Union General Secretary Dermot O'Leary noted that over the last 12 months, Bus Éireann had now expanded its services "immeasurably", with NBRU members contributing significantly to these improvements through work practice reform, more onerous rosters and other efficiencies.
He also said Bus Éireann's growth trajectory was evidenced by an increase in management positions.
Mr O'Leary said that while Bus Éireann staff had not had a pay rise in over ten years, transport colleagues in Dublin Bus, Iarnrod Éireann, the CIE group, Luas and workers elsewhere in the economy had seen pay improve over the last two years by between 2.5% and 3.75% a year.
He said staff had no desire to revist the "dark days" of last year and discommode customers, but warned that anything less than a pay improvement would inevitably lead to Bus Éireann staff demanding a ballot for industrial action.
SIPTU echoed the NBRU warning of potential industrial action if their pay demands were not met.
Transport Sector Organiser John Murphy said the real problem lay with the Government and the National Transport Authority to properly fund public transport.
Mr Murphy said that unless management could find finances through another mechanism other than payroll savings, they could end up in a situation where industrial action would remain a clear possibility.
He said some drivers were driving for 13-14 hours a day but only being paid for eight - and were coming home with less money than before the survival plan.
He said staff would view it as "death by a thousand cuts" if they were to concede further sacrifices.