Work has started on the four 900-tonne TBMs for Sydney’s $8.3 billion North West Rail Link.

The TBMs will arrive in Australia next year where they will set about constructing two 15km tunnels between Bella Vista and Epping – thought to be the country’s longest rail tunnels.

After undergoing tests in France, each TBM will be shipped to China, where the cutting faces and back-up trailers are being built, and then transported again to Sydney.

A joint venture of Thiess, John Holland and Dragados (TJHD) was awarded the project’s $1.15 billion tunnelling contract in June and has since appointed French contractor NFM Technologies to design and build its TBMs.

As well as the 15km twin-bored tunnels, the JV will be responsible for excavating the future sites of five new underground stations.

NSW Premier and Minister for Western Sydney Barry O’Farrell said: “We’re getting on with the job of delivering the North West Rail Link. The tunnel boring machines have been ordered and they’re being prepared right now.

“The North West Rail Link is the biggest public transport infrastructure project in Sydney since the Harbour Bridge almost a century ago.

“The first tunnel boring machine will be in the ground next year and the three others will follow soon after.”