By Ashley Karen
The most crucial stage of Australia’s largest road project is said to be finished in early 2023.
Sydney’s $3.2 billion motorway will link the M4 at Haberfield and the M8 at St Peters with up to four lanes each way, aiding cut travel times.
Motorway operator Transurban is increasing commissioning sharply every day to get the 7.5km mega tunnels safe and ready before the opening.
Dr Johnson Shen, a University of NSW (New South Wales) construction expert, expressed that constructing subterranean tunnels like WestConnex is one of the most complicated engineering tasks in the world.
Dr Shen stated: “If we look at other highly populated cities such as Singapore or Tokyo, they have extensive networks of underground tunnels to support their above ground transport system. Why? Because when you have limited space but still need to make the city livable for its residents, you either must start building bridges which is often impractical, or build tunnels deep below the ground,”
“No infrastructure project is ever cheap, but the benefit to the community is priceless. There are so many moving parts but ultimately, the end goal is to connect communities and make it easier for people to move around quickly, but safely too.”
He claimed that an Australian record 28 road-headers were used, mining 8.7 million tons of spoil, much of which was used in the Sydney’s second airport construction.
Shen also added: “With bulldozer-style tracks on the road-header chassis and pineapple-like heads fitted with metal picks to excavate the rock, they have done a remarkable job in these tunnels.
“They have carved out tunnels that are wide enough for an average of four lanes in each direction with the capacity to carry up to 100,000 vehicles a day.”
Andrew Head, Transurban’s WestConnex Group Executive noted that one of the little-known but most complicated parts of the project was installing a giant bridging slab.
Mr. Head pointed out: “The slab is a massive underground load-bearing structure underneath Leichhardt, that alone took 75 days to build. It involved six weeks of intense work to pour 17,000 tons or close to 1,000 truckloads of concrete, and 940 tons of custom-made steel reinforcement.”
He continued: “A prototype was developed and tested off-site first before construction started underground. We had to build it to allow one of the ramps leading to Rozelle Interchange to safely pass
overhead. Even for people who’ve worked in tunnels their whole life, this was a once in a career challenge.”
“Over the last five years, almost 12,000 people have been part of an incredible team involved in building this stage of WestConnex, making it a sustainable, safe, efficient and world class operation, largely invisible to the motorist,” Mr. Head said.
Transurban will give the community a preview in the tunnels, which link the M4 at Haberfield with the M8 at St Peters, at the commence day on 18 December at St Peters, with all public free underground bus tours booked out.
