The independent investigation team set up to look at how to secure the future of Dublin Bus has said it is "not credible" that further third-party intervention can help.
New proposals aimed at securing the future of Dublin Bus have been published by the independent investigators.
The team was appointed to examine why several previous proposals had been rejected by bus drivers.
According to the report authors, Noel Dowling and Ultan Courtney, their recommendations are the best that can be achieved.
They said that industrial relations procedures have been exhausted.
The recommendations are based on previous recommendations following Labour Court talks.
The report makes a number of recommendations regarding a variety of issues such as spare drivers, revenue protection, the working time directive, and travel/walking time.
It states that the recommendations are "the best that can be achieved in the current financial circumstances".
Any further concessions would "fatally undermine the company's cost saving plan".
The authors ask that the company, SIPTU and the NBRU endorse their report.
The level of the cash attrition from Dublin Bus is unsustainable, according to the report, and cost savings will not rescue the company.
The report's authors say they are satisfied the five-year plan produced by the company to ensure its survival will help secure its future.
However, the report points out that an increase in passengers will ultimately decide the fate of the company.
The report's authors said both the unions and the company were open in talking about the future that if there was no agreement and a lengthy strike, it would result in the orderly wind-down of Dublin Bus.
Other scenarios raised included the possibility of the company seeking examinership or being placed into receivership.
The fast-tracking of privatisation was also recognised as an option for the Government, the report states.
Dublin Bus has endorsed the recommendations made in the report and said it looks forward to a positive outcome in a ballot due to take place next week.
The Government set up the group in September to examine the dispute between unions and management.
Group set up to progress Labour Court recommendations
ICTU and Ibec proposed the establishment of the group tasked with carrying out an "urgent investigation" of how the Labour Court recommendation on cost-cutting measures at the company could be progressed.
Dublin Bus drivers have repeatedly rejected proposals, including a Labour Court recommendation and clarification, aimed at achieving financial stability at the company.
All other grades at Dublin Bus have accepted the cost reduction measures.
The Labour Court stated that its recommendations were based on the conclusion that the financial evidence, which was independently examined and verified by consultants nominated by the unions, showed that the savings were "plainly and unambiguously necessary in order to protect employment".