Technical details
CPB, Dragados & Samsung C&T JV (M8), Lendlease, Samsung, Bouygues JV (M4-M5 Link Tunnels)
Sydney, NSW, Australia
Joint Venture with KBR for independent certification services
AECOM (M4-M5 Link Tunnels, Rozelle Interchange), John Holland, Samsung, CPB joint venture (M4)
Project management and advisory, design and delivery, specialty engineering

WestConnex is Australia’s largest road infrastructure project and is a critical part of a broader plan to get Sydney, and Australia, moving again.


WestConnex will provide motorists with a continuous, 33km traffic-light free motorway network, comprising over 19km of tunnel and connections for future projects linking the north shore and northern beaches, Sydney Airport and the southern suburbs. 

Project - WestConnex


WestConnex M8 

The M8 opened in July 2020, with 9km twin tunnels connecting the M5 at Kingsgrove to a new interchange at St Peters. SYSTRA Bamser were engaged to assist the WestConnex Delivery Authority with tunnel constructability analysis during evaluation of contractor tenders. This included:

  • Reviewing tunnelling methodologies, geotechnical design reports and proposed tunnel design
  • Providing strategic advice on tunnel construction site suitability.

In addition, SYSTRA Bamser provided experienced personnel including tunnel construction, back-end works construction, and mechanical and electrical engineers to provide support the delivery phase of the project. 

WestConnex M4-M5 Link Tunnels 

Stage one of the M4-M5 Link Tunnels opened in January 2023, with a twin tunnel between the M4 at Haberfield and the M8 at St Peters and stub tunnels to the Rozelle Interchange. SYSTRA Bamser assisted AECOM by providing tunnel constructability inputs and advice during development of the Concept Design to be used in preparation of the project’s business case. This included the provision of:

  • The provision of technical and construction guidelines to inform engineering design development.
  • Review of constructability issues.
  • Advice on tunnelling site locations and space requirements.

In addition, SYSTRA Bamser provided experienced design review engineers, tunnel construction and back-end work construction engineers and a construction director during the project’s delivery phase. 

WestConnex M4 

The New M4 opened in July 2019 with 5.5km twin tunnels connecting Haberfield to Parramatta and the M4. SYSTRA Bamser were engaged to assist the WestConnex Delivery Authority with tunnel constructability analysis during evaluation of contractor tenders. This included:

  • Review of geotechnical design reports, proposed tunnel design, ground support, and ground water control strategy.
  • Review of tunnelling methodology.
  • Providing strategic advice on proposed tunnel construction sites and the commercial risks related to the construction program.

In addition, during the delivery phase SYSTRA Bamser supplied a construction manager, design engineers, tunnel construction, back-end work constructions and specialist mechanical and electrical engineers. 

WestConnex Rozelle Interchange 

The Rozelle Interchange will connect the M4-M5 Link to the Anzac and Iron Cove bridges, and the future Western Harbour Tunnel and Beaches Link.  SYSTRA Bamser are assisting AECOM with the provision of tunnel and surface constructability inputs and advice.  This includes:

  • The development of technical/construction guidelines to inform engineering design development.
  • Develop construction methodology and delivery program for pre-tender engagement information sessions.
  • Providing constructability assessment, risk assessment, and scoring as part of project tender evaluation.


WestConnex is easing congestion, creating tens of thousands of jobs, and connecting communities. Being mostly underground, WestConnex is freeing up large areas in communities that are being turned into 18ha of parks, playgrounds and recreational facilities. In addition, WestConnex is delivering and planting more than 1 million trees and plants.  


WestConnex will remove traffic congestion, cut travel times and improve air quality by moving vehicles from local roads and to underground tunnels.