The cost of building roads connecting to the WestConnex motorway could hit almost $29 billion, according to an analysis by the City of Sydney council.
The council's analysis attempts to tally the budget impact of building and widening new and existing roads needed to support traffic flows from the 33-kilometre toll-road project, which is at least six years from completion.
The analysis, which is disputed by the state government, argues WestConnex and its connecting roads combined will cost more than $45 billion, after the extra roads are added to the project's $16.8 billion public price tag.
"Every extension of the toll network, every exit and every entrance associated with WestConnex generates hundreds of millions of dollars of publicly funded road upgrades required to funnel traffic to the toll way, and to take traffic from it," lord mayor Clover Moore said.
"Just one exit from WestConnex in St Peters, for example, will require more than $1 billion of publicly funded road upgrades to manage the extra 30,000 cars that will pour into the area daily."
The government, however, argues that the City of Sydney has double-counted the cost of some roads, while other add-on roads are needed to accommodate the growing city.
For instance, WestConnex will trigger the need for another road crossing of Sydney Harbour, because traffic from the motorway would otherwise overwhelm the Anzac Bridge.
This "Western Harbour Tunnel" is in turn planned to connect to a "Beaches Link" motorway to the northern beaches. The two projects, on the council's figures, would cost about $14 billion.
"Clover Moore has completely lost touch with the Sydney outside her council boundary," said Minister for WestConnex Stuart Ayres. "While that's great for winning her local votes, it's terrible for planning a wider city with 5 million people in it."
Another road project sparked by a local increase in traffic generated by WestConnex is a scheme to widen roads through Alexandria and towards Moore Park and the eastern suburbs.
The City of Sydney's analysis, which was developed through discussions with roads officials and its own experience as a roads agency, puts the cost of these works at $1.2 billion.
It also puts the probable cost of road upgrades needed for Gardeners Road at about $400 million, with another $1.4 billion required for changes to intersections and alignments around the Iron Cove Bridge at Rozelle.
The council also homes in on the unresolved question of how the motorway will connect to Sydney Airport and Port Botany - one of the major issues for the project.
The former head of the state's road and rail agencies, Ron Christie, warned five years ago that while it was "easy to draw lines on a paper" it was another matter to "overcome the intersection problems in the very confined area around Sydney Airport".
This warning appears to have been borne out. The government has not yet released any detail on how it plans to connect WestConnex to the airport and port, though has indicated it may move a rail freight line to do so.
The City of Sydney Council puts the cost of the Sydney Airport and Port Gateway project at an extra $2.5 billion. But Mr Ayres says the full cost of the Sydney Gateway is included within WestConnex's $16.8 billion budget.
