WestConnex: new M4 Tunnels

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Designing the missing piece to deliver a connected transport network for Sydney

The new M4 Tunnels constitute a $3.8 billion section of the greater WestConnex project, which will improve the movement of motor vehicles, public transport and freight, and support the government’s plan to revitalise the Parramatta Road corridor. This project extends the newly widened M4 motorway in twin underground tunnels from Homebush to Haberfield and Ashfield and it forms the first underground section of WestConnex. These tunnels will ultimately join the New M5 underground tunnels via the M4-M5 Link to create a seamless motorway without traffic lights, providing connections to Sydney’s wider road network.

The project features over six kilometres of mainline motorway, including 5.5 kilometres in tunnels, four major interchanges, seven new bridge structures, complex cut-and-cover structures, tunnel ancillary facilities and buildings, and improvements to the local and arterial road network.

AECOM supported the project at all phases, from providing environmental and planning services directly to Sydney Motorways Corporation (SMC) to secure planning approval, to providing civil, structural and building design services, as part of a joint venture, to the design and construct contractor, a joint venture between CPB Contractors, Samsung C&T Corporation and John Holland.

The planning team were able to prepare and deliver an Environmental Impact Statement, Submissions Report and Preferred Infrastructure Report with minimal objection from stakeholders, while faced with tight delivery timeframes arising from an unforeseen change in the procurement strategy.

AECOM was also commissioned by SMC produce a series of animations to verify safety features within the project. Created from a driver’s perspective, AECOM’s animations were turned into high-quality, rendered videos providing users of the tunnel with a preview of their journey to aid them in safely navigating through the new tunnels.

The design team worked closely with the construction team through the early stages of developing an innovative solution at the tender phase focused on delivering value for money, while working in concert with all stakeholders to develop the detailed design. AECOM also provided continuity in onsite-based design support to meet the client’s need for short design-turnaround times to resolve issues encountered during the construction phase.

The new M4 Tunnels were opened to the public on 13 July 2019, a month ahead of the previously announced opening date in August 2019.