Tunnel boring machine (TBM) Ruby has begun work on the final section of the Sydney Metro West project, launching from The Bays to carve out a 2.3-kilometre twin railway tunnel beneath Sydney Harbour.

The tunnel will connect Sydney’s western suburbs to the city centre, complementing the efforts of TBM Jessie, which is working on a parallel tunnel.

TBM Ruby© Sydney Metro

TBM Ruby, named after Ruby Payne-Scott, Australia’s first radio astronomer and women’s rights advocate, is the sixth and final machine deployed for the 24-kilometre Metro West tunnel.

Weighing 1,100 tonnes, the TBM will operate continuously, moving past landmarks such as the Anzac Bridge and Darling Harbour before reaching Hunter Street in Sydney’s central business district (CBD).

Since commencing in June, TBM Jessie has excavated 615 metres and installed 2,238 concrete segments to line the tunnel walls. Together, both machines will excavate 460,000 tonnes of material and install over 16,500 segments to complete the tunnel between The Bays and Hunter Street.

This under-harbour crossing is Sydney’s second railway tunnel beneath the harbour, following the metro M1 line, which opened in August and has since seen 10 million passenger journeys.

TBMs Ruby and Jessie, designed to handle the high-pressure conditions beneath Sydney Harbour, are expected to reach Hunter Street by mid-to-late 2025.

Once operational, Sydney Metro West is set to double rail capacity between Greater Parramatta and the Sydney CBD, aiming to ease travel, connect new communities to rail services, and support growth in employment and housing across the region.