Work to build a new access road for Melbourne Airport's Terminal 4 – set to begin within months – is putting the Andrews government under pressure to decide on the location of the long-promised airport train station.

Motorists sitting in traffic jams on their way to the airport will soon be able to use a $60 million road designed to stop queues from spilling onto the Tullamarine Freeway.

How the new Terminal 4 access road will look.

Between October and December this year, Melbourne Airport plans to start building an elevated road linking the freeway and the Terminal 4 car park, which is scheduled to open by 2021. Fresh plans for the road were released on Thursday.

It's the start of a major $350 million road revamp being rolled out over the next four years to deal with a doubling of passengers between now and 2040.