Photo: The underground road will cost about $1 billion per kilometre, according to Cabinet documents. (ABC News: Luke Rosen)
New underground tunnels linking Rozelle to the northern beaches will cost almost $14 billion to build, according to confidential New South Wales Cabinet documents, a major blowout from the original estimates of $7.5 billion.
Previous spending estimates were for the two undersea tunnels, with $4.5 billion for the Western Harbour Tunnel, and $3 billion for the Middle Harbour crossing near Seaforth.
The official costing — seen by the ABC and Fairfax — is made up of construction spending of almost $14 billion, combined with operations and maintenance expenses of $8 billion over a 35-year period.
That means the new 14-kilometre underground road will cost $1 billion per kilometre to build funded by taxpayers and tolls on drivers.
The figures are contained in a "final business case", greenlighted late last year by the State Government.
A $77-million program on geotechnical work, and community information sessions on the final route are underway.
Yesterday, Premier Gladys Berejiklian downplayed community concern over smokestack locations to ventilate the tunnels, saying they "had not been finalised".
A spokesperson for Roads Minister Melissa Pavey said the Government was still doing "its homework" on the project to ensure "the best deal for taxpayers".
The spokesperson said the final costs and user tolls were not yet determined.
Further social and environment costs revealed
The loss of homes, bushland and heritage are social costs are also revealed in the Cabinet documents.
The price of acquiring about 70 homes and businesses is calculated at about $340 million.
Of that, $300 million will be spent along the Warringah Freeway — including high-value industrial land at Artarmon.
The documents also warned of the temporary loss of open space during the lengthy tunnelling operations.
Much of the foreshore at Berry's Bay, Waverton, will close to become the home of a dredging operation, removing thousands of tonnes of sludge and mud from the harbour.
A list of major permanent social impacts also mentions the destruction of protected bushland along the Wakehurst Parkway.
The Government planners suggest the use of biodiversity offsets — funding purchase of unprotected land elsewhere in NSW — to compensate for the loss of rare vegetation, animals and green space.
The report also recommended clearing of tall trees around smokestacks in parkland at Gore Hill during construction.
It suggested that "replanting should incorporate low-growing species" in the pollution dispersal zone "to facilitate air movement through the vegetation".
Permanent damage to cultural heritage is also a concern, particularly at Aboriginal sites along the Wakehurst Parkway....Read more