This matches a previous commitment of $A 5bn made to the project by the Australian federal government in April this year. Current estimates put the cost of the project at between $A 8bn and $A 13bn, with private sector expected to finance the balance.

Following an assessment of four corridors undertaken by Transport for Victoria, the western alignment via Sunshine is now the state government’s preferred route.

Trains will reach the airport via a new transport hub at Sunshine, which will provide an interchange between the airport line and regional and suburban lines, including services via the new Melbourne Metro Tunnel.

From Sunshine, trains will head north utilising both the Albion East rail reserve and sections of tunnel to reduce the impact on homes and businesses, before connecting into Melbourne Airport at Tullamarine.

Earlier this month, Melbourne Airport released plans for a major redevelopment, including a new domestic terminal and upgraded international facilities. The number of passengers passing through the airport is forecast to reach 68 million a year by 2038.

The federal government was briefed on the outcome of the route options assessment earlier this month and work is underway on the full business case which will be completed by Rail Projects Victoria next year. However, construction is unlikely to commence before 2022.