Even as Chinese-made tunnel boring machines are being assembled for a major project in Sydney, industry experts are already lauding the effort as a model of Sino-Australian partnership in advanced technology and engineering expertise.

Two of these machines — the largest of their kind in the Southern Hemisphere — will be used to construct a transportation tunnel beneath Sydney's iconic harbor. One of the machines arrived in the city late last month.

Designed with an excavation diameter of 15.7 meters and an overall length of about 113 meters, the machines include multiple intelligent technologies, including robotics for unmanned, high-precision work, according to their manufacturer.

The machines will operate up to 50 meters below sea level as part of the Western Harbour Tunnel project in New South Wales. A 6.5-kilometer tunnel is scheduled to open to traffic in 2028, the state government said.

Built by China Railway Engineering Equipment Group, or CREG, the machines are expected to complete their work in about a year. Mark McLean, CREG's general manager for the Australian market, said the machines, which use slurry technology, are "equipped and built to cope with the ground conditions we may encounter on the project".

"Why did we go to China to get our technology? The main reason is the steel manufacture, the design work — it's pretty much second to none anywhere in the world now," he said.

Emily Kahn, a mechanical project engineer at Acciona Construction Australia, the contractor delivering the project, said one of the two machines ranks among the largest tunnel boring machines ever deployed in the Southern Hemisphere, with a total weight exceeding 4,000 metric tons.

"It's going to excavate 1.5 kilometers of a three-lane motorway with twin tunnels. Unlike previous tunnel boring machines … the immense size allows it to fit three metro-sized tunnels within each tunnel … it highlights the unprecedented scale and capability," Kahn said.

Handling challenges

The section of the Western Harbour Tunnel to be bored lies beneath Sydney Harbour, where ground conditions are particularly challenging, she said, adding the machine is "well-equipped to handle these conditions".

"CREG is globally renowned for its technological capability in the production of very large tunnel boring machines. We've already experienced high levels of collaboration and are very confident CREG will meet expectations," she said.

Christian D'Hondt, construction manager of the tunnel project at Acciona, said the project was initially conceived as a submerged tube tunnel, which would have necessitated dredging operations and cofferdams, resulting in significant environmental and community impacts.

Acciona worked closely with CREG to design a bespoke machine suited for tunneling beneath Sydney Harbour, he said.

McLean of CREG described the Sino-Australian partnership on the project as a major achievement.

While language differences can sometimes present challenges, the teamwork has been excellent, he said.

The project can also help reflect the rising confidence in Chinese technology and expertise going global, he said. "I've been personally traveling to China for more than 10 years, and the change that I see is absolutely amazing in terms of the infrastructure that's being built. So, Australia leveraging off what's happening in China can only be a success."

Contact the writers at xinxin@chinadaily.com.cn