A Complete Guide To Westconnex


Image credit: The Australian.

With an estimated cost of $16.8 billion, the Westconnex project is referenced as Australia’s largest infrastructure project. Spanning 33 km of motorway (19km of which are tunnel, with 14 km aboveground), the finished product will connect the Port Botany and Kingsford Smith Airport precincts with Sydney’s west and south-west.

With the project breaking ground in 2015 and an anticipated completion date in 2023, the project centres mainly on the M4 and M5 corridors (including a tunnel which will connect the two).

What Westconnex will provide

In addition to the projected 10,000 jobs that will be created during the construction alone, the benefits that the project aim to deliver are as follows:

  • Greater connectivity and significantly reduced travel times
  • Reduced congestion (which has a $6 billion per annum impact in Sydney)
  • Improved liveability in Sydney, by enabling urban renewal and decreasing greenhouse gas emissions by over 610,000 tonnes per annum
  • Supporting long-term economic growth in Sydney through connection to key employment hubs and the west


A Sydney consortium, Sydney Transport Partners (led by Transurban) is delivering the project in conjunction with the New South Wales State Government. A 49% residual stake in the project will be retained by the Government. However, recent reports have indicated that the Government is considering selling its remaining stake to further bolster its war chest for its $97 billion infrastructure program. This would enable more hospitals and schools to be built, in addition to road and rail networks. Dominic Perrottet, the NSW Treasurer, stated that "the scoping study will look at all the available options".

Westconnex delivery timeframes

Given the scale and complexity of the Westconnex project, it will be a phased delivery:

  • Stage one (completed): the first underground part of the Westconnex, it offers twin tunnels with three lanes in each direction and connects to the widened M4. This was a 6.5 km section, of which 5.5 km was underground tunnel.
  • Stage two (86% complete): a duplication of the M5 East from a new St Peters interchange, through to the King Georges Road interchange at Beverly Hills. This stage will see the delivery of 9 km of twin motorway tunnels between Kingsgrove and Alexandria, both with two lane capacity in each direction and capacity for a third.
  • Stage three (59% complete): delivery two tunnels which connect the new M4 at Haberfield and the new M5 at St Peters. The most pivotal piece in the project, this involves dual 7.5 km tunnels between the new M4 and M5, each with capacity of up to four lanes in each direction

Similarly to the M7 motorway, the Westconnex will utilise a distance-based toll system calculated on the sections used and there will be a maximum cap applied.

Westconnex FAQ's

What does Westconnex provide for Sydney?

In short, catering for Sydney’s projected population growth effectively requires both public transport network improvements and enhanced road infrastructure. With an estimated additional 1.6 million people living in the Sydney catchment in 2031 than there were in 2011, greater capacity for passenger, freight and commercial traffic is required to accommodate this growth.

Surely funding public transport initiatives to incentivise less car travel is a wiser investment?

Westconnex is one of 80 projects listed in the NSW Long Term Transport Master Plan, aimed at meeting the growing demands on Sydney’s transport network. The Plan takes a holistic view of the transport system, with the four-year $41.5 billion investment encompassing both roads and public transport projects. These include Light Rail, Metro and bus fleet upgrade projects. It is worth noting, however, that by 2036:
  • in excess of 70% of the portion of increased travel in Sydney will be by car
  • bus travel will represent around 45% of all public transport, which is entirely road-network reliant

Who are the Westconnex contractors?

By stage, the key design and construction partners are:
  • Stage one - M4 East: CPB Contractors, Samsung C&T Corporation and John Holland JV
  • Stage two - New M5: CBP Contractors, Dragados and Samsung JV
  • Stage three - M4-M5 Link Tunnels: Lendlease, Samsung C&T Corporation and Bouygues Construction JV


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