The cost of building a motorway to the new Western Sydney Airport risks blowing its $1.25 billion budget unless the road project's size is reduced or extra funding found, leaked government documents reveal.
The internal documents show NSW's transport agencies now estimate the cost of the M12 motorway at $1.38 billion – $130 million "above the available funding" from the federal and state governments.
The state's transport agencies have been investigating "options for securing additional funding" for the four-lane motorway, the documents show.
The new motorway will provide motorists a direct link to Western Sydney Airport.Credit: Rob Homer
Alternatively, the agencies "identified a reduced scope" for the project, which would allow it to be built within the approved $1.25 billion budget. The documents do not elaborate on what parts of the project could be scaled back.
Roads and Maritime Services and other agencies did consider a "tolling strategy" for the 16-kilometre motorway, which will connect the M7 at Cecil Hills to the Northern Road at Luddenham and offer motorists direct access to the new airport at Badgerys Creek.
However, the Berejiklian government in September ruled out tolling the M12.
Roads Minister Melinda Pavey.Credit: AAP
Labor's transport spokeswoman, Jodi McKay, said the Berejiklian government needed to "come clean" on how it would find extra funding for the motorway or whether it would be forced to reduce the size of the project.
"This is the sort of information that people deserve to know before they walk into a polling booth [in March for the state election]," she said.
"There is obviously going to be a nasty surprise waiting for us if we get into government. It is time they come clean on what is happening with major infrastructure projects like the M12."
Roads Minister Melinda Pavey said the business case for the motorway had yet to be finished as work continued to refine the design based on the identified road corridor.
But she reiterated the government's position that there would be no toll on the M12.
A spokesman for federal Urban Infrastructure Minister Alan Tudge echoed the NSW Roads Minister's comments but did not address questions about whether the Minister preferred to reduce the scope of the project or seek alternative funding.
The federal government has committed $1 billion in funding for the motorway, while NSW has allocated $250 million.
Under their plans, the M12 motorway is due to open before airlines are expected to begin passenger services at the $5 billion-plus western Sydney Airport in 2026. Initial earthworks for construction of the airport began in September.
The motorway will have a central median to separate opposing traffic flows and transport officials will make provisions for it to one day be expanded to three lanes in both directions.
An environmental impact statement for the M12 motorway is due to be released early this year.