The West Gate Tunnel Project is in full swing beneath Melbourne’s inner west, with tunnel boring machines (TBMs) Bella and Vida at the helm of the ambitious twin-tunnel build.
TBM Bella, already in operation, is digging the 4-kilometre westbound tunnel. The machine will soon be joined by TBM Vida, set to excavate the 2.8-kilometre eastbound tunnel. Together, they are boring through up to 27 metres of basalt and bluestone under Yarraville, linking the Maribyrnong River with the West Gate Freeway.
Each TBM is a 4000-tonne behemoth, stretching 90 metres long and standing 15.6 metres tall. Their 450-tonne cutterheads – each armed with 96 tools – rotate up to three times per minute when tackling dense rock. At full operation, they can excavate up to 9 metres of tunnel per day, running continuously 24/7.
Bella and Vida will jointly remove 1.5 million cubic metres of soil and rock – enough to fill a sports arena. As they move, each TBM installs a watertight concrete lining, creating a sealed tunnel structure behind them.
Tunnel excavation began from Whitehall Street in Yarraville, with outbound and inbound portals located near the West Gate Freeway in South Kingsville. The outbound tunnel, already underway, will take around 18 months to complete. TBM Vida previously completed a 2.8-kilometre breakthrough under Yarraville in February 2023.
Behind the TBMs, crews install road pavement, electrical systems, ventilation, and safety infrastructure. Up to 20 personnel work inside each machine at a time, often under pressurised conditions up to 35 metres below ground. Operators undergo specialised hyperbaric training and may spend up to two hours depressurising post-shift.
Above ground, a separate feat is unfolding. A 116-metre-long launching gantry is assembling an elevated road over Footscray Road. Standing 40 metres high, it lifts and secures precast segments (manufactured in Benalla) using steel cable tensioning and grout injection to form spans. This method enables construction with minimal traffic disruption and maintains port access for freight.
When complete, the West Gate Tunnel will provide a crucial alternative to the West Gate Bridge, improving travel times and diverting over 9,000 trucks daily from inner-west roads.
