The Minister for Transport, Mr Cullen, has asked the National Roads Authority (NRA) to draw up outline proposals for a new outer ring-road around Dublin to relieve gridlock on the M50.
The proposals are expected to be considered as part of a major 10-year transport plan to be discussed by Government ministers next month.
Officials at the Department of Transport are currently finalising proposals for the multibillion euro plan, to be brought before the Cabinet committee on transport, which is chaired by the Taoiseach, Mr Ahern.
The proposals will include a metro link from Dublin city centre to the airport and Swords and a tunnel to connect Heuston Station to other Dublin rail lines and Luas.
Other proposals to be examined include a dual-carriageway linking the cities of Galway and Limerick, extending the DART to Kildare, and a new urban rail-line to Dunboyne.
In recent weeks, Mr Cullen asked the NRA to provide basic proposals on a new outer orbital route around Dublin, in the wake of growing support for the project.
According to sources in the Department of Transport, Mr Cullen is "anxious to accelerate the project".
"We need to learn from the mistakes of the past, where the plans weren't there to meet demand," according to one Department official.
The NRA has been asked for the feasibility of an optimum route, including financing possibilities. The authority is expected to provide details from an original feasibility study from three years ago, which traced a basic route from Drogheda, through Navan and on to Naas.
There are no detailed costs on the route at present, but the 70 kilometre route would cost up to a billion euro.
The NRA is understood to have told the Government that the project could not be delivered under existing budgets.