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There have been various forms of Sydney Bypass for decades. Some have taken the form of local suburban roads which have gradually become more and more congested until they were no longer effective as a bypass. Others have been proposals that never eventuated. When freeways were first built in the Sydney region, they were all designed to radiate from the city's central business district.
Disjointed sections 
Some disjointed sections of such planned roads were built but during the 1970s, the focus changed and many sections of these proposed roads were never built. Such disjointed segments of freeway can be seen in such places as Hunters Hill near Gladesville Bridge, where segments of the North West Freeway were constructed.
Around this time, freeway planning shifted to building freeways as bypasses.
For decades, it has been desired to construct a Freeway standard bypass of Sydney as part of the National Highway, connecting the Sydney-Newcastle Freeway to the Hume Highway to allow through traffic to be separated from local traffic.
The North West Freeway was originally intended to fork in the Lane Cove Valley, with one fork following what is now the M2 corridor and the other following what is now the Sydney-Newcastle Freeway. If these had been built, traffic would have looped at that fork in much the same way as traffic from Burns Bay Road loops around the approach to Gladesville Bridge to turn west on Victoria Road. The Lane Cove section was abandoned for environmental reasons, leaving the Sydney-Newcastle Freeway to terminate at Pennant Hills Road.
Recent proposal 
In recent years,[when?] the Federal Government proposed that the M7 would form part of a bypass route, with a new road branching off the Sydney-Newcastle Freeway near Mount White and crossing the Hawkesbury River with a new high-level bridge to join the M7 at its distinct northwestern corner. Hence, the road would avoid the steep grades of the Mount White section of the Sydney-Newcastle Freeway immediately north of the existing low-level bridges across the Hawkesbury River and would be a quite direct bypass of Sydney that would be separated from much of Sydney's Commuter traffic.
A study was undertaken into options for connecting the Sydney-Newcastle Freeway with the M7. At the preliminary stage of that study, the Roads and Traffic Authority decided that the primary goal of the new road was the best possible relief of traffic on the existing route, Pennant Hills Road. Corridors for that proposal were broadly defined as types A, B and C.
- Type A options were essentially from the existing end of the Sydney-Newcastle Freeway to somewhere on the M2.
- Type B corridors branched off the Sydney-Newcastle Freeway in the vicinity of Berowra and crossed the environmentally sensitive Galston Gorge.
- Type C corridors were along the general lines of the Federal Government proposal.
The need to reduce traffic on Pennant Hills Road made the reduction of commuter traffic more urgent than that of traffic bypassing Sydney. As such, type B and C options were rejected early in the planning process.
Four type A options were identified. All involved extensive tunnelling. One of these, following the Hornsby - Epping railway line near the F3 and underneath Pennant Hills Road towards the M2, was selected as the preferred option.
The background documents to the route study indicate that it is predicted that the Sydney-Newcastle Freeway will need to be upgraded to 3 lanes each way plus climbing lanes up the hills and will still run out of capacity by 2021, at which time a type C corridor will be needed in addition to the type A tunnel currently proposed.
Independent review 
On 17 February 2007, the Hon Jim Lloyd MP (the federal Minister for Local Government, Territories and Roads) announced the establishment of an independent review of the F3 to M7 Corridor Selection. The review was carried out by the Hon Mahla Pearlman AO, who is a former Chief Judge of the NSW Land and Environment Court. The report was released on 14 September 2007. The conclusions of the report were that the proposed tunnels should proceed but that planning for the longer term connection between the Sydney-Newcastle Freeway and the M7 should also commence immediately.
- http://commcons.skm.com.au/f3tosydneyorbital F3 to Sydney Orbital route study
- http://commcons.skm.com.au/f3tosydneyorbital/documents/cfg2_dural_31july2002.pdf Dural meeting 31 July 2002 - Note traffic predictions on page 5
- http://www.dotars.gov.au/roads/F3toM7Review/index.aspx Review of the F3 to M7 Corridor Selection
See also