Sydney Metro West tunnels enter the final stretch as mega borers advance towards Parramatta

This latest milestone means more than 80 per cent of tunnelling for the city-shaping project has been completed.   

TBM Dorothy broke through to arrive at the junction caverns in February, after spending three months tunnelling 1.1 kilometres from Clyde.

TBM Betty is tracking slightly ahead, having arrived at the junction caverns in December 2024 after carving out the tunnel parallel to TBM Dorothy. TBM Betty spent seven weeks traversing the cavern and undergoing scheduled maintenance and is currently tunnelling towards Parramatta. 

The junction caverns are an important component of the new railway as they feature service tunnels linking to the above ground stabling and maintenance facility, where the network’s new fleet of trains will be housed when not in service.  

Since starting their westward tunnelling journey in September 2024, TBMs Betty and Dorothy have been working around the clock to excavate about 200 metres of tunnel each week.  

So far, the TBMs have carved out 5.7-kilometres of twin tunnels between Sydney Olympic Park and Clyde, removing more than 1.1 million tonnes of material, equivalent to about 180 Olympic-size swimming pools.  

Along the way, the TBMs have installed more than 41,000 precast concrete segments to line the new tunnel walls. Each precast segment weighs about 3.8 tonnes, with six segments pieced together to form one ring around the tunnel.  

Both TBMs will build a further 1.1-kilometre section of tunnels to reach the site of the future Parramatta Metro Station by mid-year. 

Tunnelling on the Sydney Metro West project has been ongoing since April 2023.  

Current TBM progress includes:

• TBMs Betty and Dorothy have each built over 75 percent of the nine kilometres of tunnel between Sydney Olympic Park and Westmead.
• TBMs Daphne and Beatrice completed 11-kilometre twin metro tunnels between The Bays and Sydney Olympic Park in October 2024.
• TBMs Jessie and Ruby have completed 33 per cent of the 2.3-kilometre tunnels between The Bays and Hunter Street in the Sydney CBD. The remaining 1.7-kilometres of the alignment is being excavated by roadheader machines.

As is tunnelling tradition around the world, TBM Betty and Dorothy have been named after notable women for luck. TBM Betty is named after Olympic champion and former Parramatta local Betty Cuthbert, while TBM Dorothy is named after human rights activist Dorothy Buckland-Fuller. 

Sydney Metro West is targeting an opening date of 2032.