The bypass project had been planned many years earlier. During the years of planning a misunderstanding by residential developers led to new roads and housing being constructed on
Roads & Traffic Authority land at the end of Anzac Road in Bangor. This caused the proposed position of the bypass to shift slightly north Preparations for the Bangor Bypass included changing traffic flow between
Bangor,
Woronora and
Sutherland. This was largely due to a stretch of road known as the "Woronora bends", a collection of steep hairpin bends along Menai Road. In June 1990, a changeover from the bends shifted traffic from Menai Road onto a small stretch of Akuna Avenue and a new road called River Road. In 2001, traffic was shifted onto an extended River Road via the new
Woronora River Bridge, replacing Menai Road via the older Woronora Bridge. Construction on stage 1 of the Bangor Bypass was commenced by
Abigroup in June 2003 with it opening in February 2005. Stage 2 of the bypass project, commenced in 2009 and completed in early 2011, extended the Stage 1 New Illawarra Road southwards and joined it with the rest of New Illawarra Road at
Barden Ridge, allowing the then Metroad 6 (now A6) to bypass Old Illawarra Road. The passing of the
Main Roads Act of 1924 through the
Parliament of New South Wales provided for the declaration of Main Roads, roads partially funded by the State government through the
Main Roads Board (MRB). With the subsequent passing of the
Main Roads (Amendment) Act of 1929 to provide for additional declarations of State Highways and Trunk Roads, the
Department of Main Roads (having succeeded the MRB in 1932) re-aligned the western end of Main Road 663 (originally declared from the intersection of Princes Highway and Old Princes Highway at
Sutherland and along The Grand Parade, Linden Street, River and Menai Roads to the intersection with Old Illawarra Road in
Menai on 22 January 1993) along River Road and Bangor Bypass to the intersection with New Illarwarra Road, on 20 February 2009. updated road classifications and the way they could be declared within New South Wales. Under this act, Bangor Bypass retains its declaration as part of Main Road 663. ==Exits and interchanges==