A 10-YEAR-OLD design for a future railway line to Melbourne Airport is ''no longer viable'' because the regional rail link is being built on the reserved corridor of land.
The loss of what was previously considered the best pathway for an airport railway line makes the Baillieu government's pledge to begin developing the airport rail link more difficult.
The former Bracks government reserved a corridor of land in Melbourne's western suburbs for two future tracks to the airport, after it decided in 2001 that an airport rail link was not then economically viable. The route was proposed to run alongside the Sunbury line to Albion, then branch off to Tullamarine using the Melbourne-Sydney goods line, which it would share with freight trains.
This route remains the preferred option in Melbourne Airport's most recent master plan, and is the only airport rail route for which land has been reserved.
But a recent study found building the rail link along the corridor would mean ''considerably increased land acquisition, social impact and cost'' than had been assumed in 2001, when the former Labor government first moved to reserve the corridor.
In a 2011 briefing to Public Transport Minister Terry Mulder, released to Fairfax Media through freedom-of-information, the former director of public transport, Hector McKenzie, advised that ''the design scheme used for the 2001 business case is no longer viable''.
Two tracks are being built alongside the Sunbury line as part of the $5.3 billion regional rail link project, which will separate Geelong, Ballarat and Bendigo trains from Metro trains when it opens in 2016, removing rail bottlenecks.
''The study recommended that a new investment decision process be undertaken considering alternative airport link options around new rail routes,'' Mr McKenzie wrote.
A map, separately obtained by Fairfax Media, reveals a string of other possible alignments for an airport rail link. They include: a spur through Westmeadows, branching off from either the Craigieburn or Upfield line; extending the Showgrounds spur line through Maribyrnong and Essendon, with new subway stops at Highpoint Shopping Centre and Essendon Fields; and a tunnel all the way from Southern Cross Station to Tullamarine.
The Baillieu government is part-way through a two-year, $6.5 million study of a Melbourne Airport rail link. Mr Mulder said the government had not ruled out any options.
''The government's promised airport rail link study started with no preference for any particular route, nor did it rule any potential route out. We are seeking the best option for Victoria,'' he said. ''The study takes into account all previous studies, current data on population, transport and the needs of our growing city.''
Public Transport Victoria spokeswoman Andrea Duckworth said the Albion corridor was still a viable option for an airport rail link, although the design from the 2001 business case was outdated.
''The shape of the Melbourne rail network has changed significantly since 2001, with construction of the regional rail link currently under way, the recent completion of three new stations, and the extension of the network to South Morang,'' she said.
''The Airport Rail Link Study will prepare a new business case in light of all the changes to the rail network in recent years, including the construction of the regional rail link.''
Ms Duckworth added that the airport rail link would not be built before the Melbourne Metro tunnel, a planned new subway beneath the city centre connecting the Sunbury and Pakenham lines.
''In order to proceed with projects like an airport rail link, Melbourne's rail network needs more capacity through the city,'' she said. ''The Melbourne Metro project is so important to the future of the rail system because it will provide the extra capacity that will enable projects like a rail link to Melbourne Airport to become a reality.''
About 40 million people a year are expected to visit Melbourne Airport by the end of the decade. The Tullamarine Freeway is currently the only route to the airport, and is already beyond capacity in peak times.
Travel times along the freeway between the airport and Melbourne's CBD are forecast to gradually get worse if nothing is done.