Future sections of the M8 are being constructed as the Western Harbour Tunnel, which will connect the M8 at Rozelle Interchange to the A8 at Neutral Bay.

Tunnel connections to the future M6 Motorway towards Southern Sydney and Wollongong have already been built at where the route curves north.

[5] The route continues running parallel to Princes Highway past St Peters along the M4-M8 Link.

[8] The strategic concept for the M5 East Duplication was placed on public exhibition between November 2009 and March 2010 for community and stakeholder feedback.

The New M5 had the potential to impact the critically endangered Cooks River/Castlereagh Ironbark ecological community and the green and golden bell frog, which are listed under the Commonwealth Environmental Protection and Biodiversity Act 1999.

Environmental approval[2] from the federal Minister for the Environment was granted on 11 July 2016 and construction commenced later that month.

[3] The next section of the M8 that opened, the M4-M8 Link, is the third stage of the Westconnex project and has a long history in similar forms.

It was previously known as the "M4 South"[17] and follows much of the alignment of the Inner West Motorway which originally formed the northern end of the F6 Freeway in the 1948 Cumberland County Plan to build an inner-city bypass and link the airport and shipping terminals.