The cost to taxpayers of building the first three stages of the proposed F6 Extension between Arncliffe in Sydney's south and Loftus has been put at more than $9 billion.
The figures, obtained from leaked cabinet-in-confidence documents, also estimate the government will be on the hook for an extra $2.2 billion in operational costs for the tollroad over 35 years.
Under the plans mirroring those for WestConnex, tolls for each of the three sections will range from about $3.50 to $3.80 – capped at just over $8 for a one-way trip along the entire motorway – in today's dollars and rising annually at the rate of inflation or 4 per cent, whichever is greater.
The leaked documents, obtained by Fairfax Media and the ABC, help explain why the government last month shelved plans to build a final stage between Loftus and Waterfall.
A new bridge is proposed to cross the Georges River alongside the Captain Cook Bridge as part of the second stage.Credit: John Veage
While it faced a backlash for the threat posed to the Royal National Park, an internal analysis reveals the final stage exposed the government to a "funding shortfall" of about $3.5 billion because it was the one section that was to be free of tolls.
The analysis says building only three stages covering about 23 kilometres is "more financially viable".
In committing last month to constructing the first stage between a junction for WestConnex at Arncliffe and President Avenue at Kogarah, Premier Gladys Berejiklian declined to release details about the design, cost and tolling, saying such specifics would be provided mid next year.
But a leaked business case prepared by Roads and Maritime Services details the project at length, including plans for a ventilation stack for the first stage at the corner of Marsh Street and an on-ramp to the M5 East motorway at Arncliffe.
The cost of the first three stages of the F6 Extension is put at more than $9 billion.Credit: John Veage
The document, marked "sensitive", says an interchange at President Avenue is critical because it is the only place for vehicles to enter and exit the new toll road north of the Georges River.
While not part of the project, the benefits of eventually building a direct link between the first stage of the F6 Extension and the northern end of General Holmes Drive are also outlined. It will help improve connections to Sydney Airport, Port Botany and the eastern suburbs.
The business case reveals about 60 homes will need to be acquired for the three stages, most of which will be between San Souci and Miranda.
But the number of homes acquired at San Souci can total more than 50 if a western portal to the roadway tunnels is chosen. The business case lists a central portal as the preferred option, which will require the acquisition of about 30 homes.
The tunnels needed for the F6 – also referred to in the documents as the SouthLink – are among the most expensive elements of the project, costing an average of almost $120,000 a metre.