PARRAMATTA ROAD would be carved open and an eight-lane motorway dug beneath in plans being developed for a huge expansion of Sydney's tollway network.
The plans, being drawn up by the government's infrastructure adviser, Infrastructure NSW, envisage three new motorways in Sydney, to be paid for partly by a new tolling system across the city.
The motorways - another M5 East tunnel, an M4 East running beneath Parramatta Road connecting to the city, Botany and the airport, and a link between the F3 and M2 - would be presented as one package to transform the economy of Sydney.
But they would cost $10 billion to $15 billion in government money, as well as tolls. And the scale of the projects would make any other big investment in transport beyond the north-west rail link unlikely for decades.
Advertisement Details of the plans remain patchy, with Infrastructure NSW not due to release its state infrastructure strategy to the O'Farrell government for another month. But officials and industry sources reveal a number of differences with previous proposals for an M4 East and M5 tunnel duplication.
One of the main differences is that the new plans contemplate cheaper but more "high impact" construction techniques - ''more surface construction to make construction cheaper'', one source said. Another source said this meant using "cut-and-cover" construction along Parramatta Road.
Previous plans for an M4 East tunnel envisaged drilling underground to extend the M4 from Strathfield closer to the city, with minimal disruption to the surface.
The cut-and-cover techniques would require tearing up sections of Parramatta Road, laying a motorway underneath, and relaying the surface road on top of the tunnel.
This would be significantly cheaper but intensely disruptive. It would probably also require the acquisition of property next to the road.
Another difference is that the new M5 East tunnel would connect to the extended M4 East near Sydney Airport. The M4 East would reach the airport by following the Alexandra Canal.
''It is no secret that Infrastructure NSW is considering a range of motorway projects - and specifically the M4 and M5 - as part of developing a 20-year state infrastructure strategy,'' a spokeswoman said.
''Infrastructure NSW is looking at a number of options that are aimed at one outcome: growing the NSW economy.''
The motorways would have dedicated truck lanes to improve freight access to Port Botany. Tolls would be reintroduced on the M4.
The development of the motorway plans comes amid sharpening divisions within the government over transport policy.
On Saturday the Herald revealed the top bureaucrat in the state transport department Transport for NSW, Les Wielinga, had quit the board of Infrastructure NSW last month.
Transport for NSW and Infrastructure NSW, established under the chairmanship of the former premier Nick Greiner, will unveil their respective plans for the state in coming months and they are expected to be completely at odds.
Infrastructure NSW will make the motorway plan a priority, while Transport for NSW will emphasise public transport. Mr Wielinga could not defend both.
It is understood Infrastructure NSW has had talks with private equity firms about making the package of motorway projects attractive to foreign investors and superannuation funds.
It is understood that Infrastructure NSW - not Transport for NSW - is pushing to manage construction and financing.
The government does not have to follow the recommendations of Infrastructure NSW, meaning the adviser's plans for Parramatta Road are not a fait accompli. But the government does have to release the plans to the public once it has received them.
Mr Greiner has often spoken of the need to redevelop Parramatta Road, saying it resembled ''Beirut on a bad day''.
Last year the NRMA proposed running light rail down Parramatta Road in the event an M4 East tunnel was built. But it is unlikely that Infrastructure NSW's plan recommends this.