A NEW train tunnel from the CBD to Tullamarine is being considered as part of a long-awaited rail link to Melbourne Airport.

A state government study into the feasibility of an airport connection has examined about 80 route options designed to ease traffic congestion and cope with the airport's future growth.

One of the options is a direct tunnel from the CBD that would cut through the north-west suburbs. Credit:Craig Abraham

One of the options is a direct tunnel from the CBD that would cut through the north-west suburbs. Another is a rail link between Albion North and the airport, connected to the city via the Sunbury train line.

Transport officials say both proposals are largely reliant on the Melbourne Metro rail project, a proposed tunnel between South Kensington and South Yarra that would involve building five underground stations: Arden, Parkville, CBD North, CBD South and Domain. The nine-kilometre tunnel would link the Sunbury rail line, in Melbourne's north-west, to the Dandenong rail corridor in the outer south-east, allowing an extra 24,000 passengers an hour to travel through the network.