Sydney opens new underground highway 01 Aug 2019

The M4 element of the WestConnex underground highway in Sydney, Australia, has opened to traffic, while work on the other project contracts, including the M5 route, the M5-M4 link, and the Rozelle interchange, continues. The 5.5km M4 route features twin tunnels with a three-lane highway in each direction and was finished on time and within its budget of AU$3.5 billion, ready for its grand opening in July (2019). The M5 link is currently 84% complete and on track to open for traffic in early 2020. Running through the west of Sydney, excavation of the M4 section was completed by the CPB/Samsung/John Holland JV and was undertaken by 21 roadheaders and 11 Robodrill bolting rigs working across four sites. The route also includes 50 cross passages for a total underground excavation of about 14km.

Fig 1. Full scope of the WestConnex project

Excavation work on the AU$4.3 billion WestConnex M5 contract by the CPB/Dragados/Samsung JV was completed in December 2018. The 9km twin three-lane tunnels linking Kingsgrove to a new St Peters Interchange to the southwest of Sydney was also a roadheader operation with 20 roadheaders and 11 Robodrill bolters working from four construction sites. In addition to the main tunnels, the M5 route includes 75 cross passages.

The Lendlease/Samsung/Bouygues JV began excavation on the third element of the underground network, the M4-M5 link, in March 2019. The 7.5km twin four-lane route connects the M4 at Haberfield with the M5 at St Peters (Fig 1). Other elements of the contract include:

• Ramps between the main tunnels and the surface interchange at St Peters
• Ramps between the main tunnels and the surface connection at Wattle Street
• A ventilation facility at St Peters
• Integration with the ventilation facility at Haberfield

Stub tunnels to connect the underground road network to the Rozelle Interchange and to future extensions for the Western Harbour Tunnel and Beaches Link are also part of the contract.

The final contract for the current programme of contracts is the Rozelle interchange, an AU$3.9 billion underground junction that will be one of the largest in the world. The JCL John Holland/CPB Contractors JV, was selected in December 2018 as the successful design and construction contractor. Design plans are continuing and construction is expected to begin this year (2019).

The new Concord Interchange with entrance to M4 tunnels

Both M4 and M5 excavations were supported by specialist tunnel construction software developer, VMT, who supplied the guidance systems for the roadheaders, ensuring they excavated the designed tunnel profile and that bolters correctly positioned the tunnel support. VMT provided full-time service for seven months on the M4 excavation and for a period of about two years on the M5 project. Both were “positive projects,” said Matt Jarvis, VMT Regional Sales Manager.

VMT is now working on the M4-M5 link element of WestConnex with the same teams involved as the initial M4 and M5 projects and a new generation of equipment. The major change to the VMT system is an updated user interface, which is better lit and can be accessed without opening the housing. This eliminates the risk of water and dust ingress, while also allowing for quicker and easier troubleshooting by the project team. VMT have also bid for the final WestConnex contract, covering the Rozelle Interchange. Award of that contract is imminent.

“The M4 tunnels are a game changer for the people of western Sydney, doubling the capacity of the corridor between Homebush and Haberfield,” said Deputy Prime Minister of Australia and Minister for Infrastructure, Transport and Regional Development, Michael McCormack, at the opening. “We know congestion in our cities is a real problem and the Australian Government is doing everything it can to fix it through our record AU$100 billion pipeline of infrastructure projects over the next decade.”