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Tunnelling project hits milestones

The West Gate Tunnel Project will upgrade the West Gate Freeway and link it to the city and CityLink, providing road users with an alternative to the West Gate Bridge.

In preparation for the beginning of major tunnelling works in 2019, the North Yarra Main Sewer – a 100-year-old, 2.6 m diameter brick sewer routed below Whitehall Street in Footscray and Yarraville, carrying 20 per cent of Melbourne’s sewage – needed to be diverted.

A Herrenknecht microtunnel boring machine (MTBM) named ‘Mollie’ was launched in September and subsequently excavated 600 m in 35 days.

Moving at approximately 12 m/d, the MTBM created a new route as it installed glass reinforced plastic lining inside the tunnel to seal and strengthen the new infrastructure.

With breakthrough achieved, the MTBM has now been transported from the northern portal project site in Melbourne to Herrenknecht’s Thailand plant, where it will be sent off for use on another project.

At the northern portal, excavation of the launch shaft for the two tunnel boring machines (TBM) – ‘Bella’ and ‘Vida’ – ordered in January is almost 100 per cent complete.

The 15.6 m diameter TBMs will build a 6.8 km tunnel between the Maribyrnong River and the West Gate Freeway.

The gantry cranes are now in place to lift the heaviest parts of the machines into place, with one of the 450 t cutterheads already on site and ready to be lowered into the shaft.

On the western side of Williamstown Road, a pipejacking machine is now being used to relocate a 300 m section of a City West Water sewer main that crosses under the freeway.

Once this relocation project is completed, the TBMs will have the space required to breakthrough safely.

For more information visit the West Gate Tunnel Project website.

If you have a project you would like featured in Trenchless Australasia contact Assistant Editor Chloe Jenkins at

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