Meanwhile, a train line to the airport remains off the agenda.
A VicRoads spokeswoman yesterday confirmed preliminary work had been done on plans for the freeway link, which would in effect extend the Tullamarine Freeway by about seven kilometres to Sunbury. The freeway would link the airport to the planned outer ring road, a 73-kilometre, eight-lane freeway that travels north of the airport.
The ring road will not be built for a decade, but its route is being decided now.
A final proposal for the ring road, released yesterday, shows the new link from the airport would either pass around the township of Bulla or through Oaklands Junction.
The freeway extension was proposed in June, but was not part of the outer ring road plan. While the Brumby Government is willing to consider another freeway to the airport, a rail line from the CBD remains off the agenda.
On Monday, speaking at a transport conference, Roads Minister Tim Pallas said it was not a priority. ''It's time we recognised the SkyBus service to Melbourne Airport is an enormously popular form of mass transit that successfully fulfils the need for public transport to the airport,'' he said. ''Should taxpayers devote a couple of billion dollars to a huge infrastructure project so Melbourne can boast of the dubious honour of an airport rail link?''
Before the 1999 election, Labor promised to build a ''rapid transit link'' to the airport.