West Gate Tunnel Project: 4000-Tonne Machines Excavate Arterial Route beneath Melbourne's West
The West Gate Tunnel Project is currently in full swing beneath Melbourne's inner west, with tunnel boring machines (TBMs) Bella and Vida spearheading the ambitious twin-tunnel construction.
TBM Bella, already operational, is excavating the 4-kilometre westbound tunnel. It will soon be joined by TBM Vida, tasked with digging the 2.8-kilometre eastbound tunnel. Together, these colossal machines are tunnelling through up to 27 metres of basalt and bluestone beneath Yarraville, connecting the Maribyrnong River with the West Gate Freeway.
Each TBM is an immense 4000-tonne structure, stretching 90 metres in length and standing 15.6 metres tall. Armed with 96 tools, their 450-tonne cutterheads rotate up to three times per minute when confronting dense rock. Operating at full capacity, they can excavate up to 9 metres of tunnel per day, working continuously around the clock.
Bella and Vida are anticipated to remove a total of 1.5 million cubic metres of soil and rock—enough to fill a sports arena. As they progress, each TBM installs a watertight concrete lining, forming a sealed tunnel structure in their wake.
Excavation of the tunnel commenced from Whitehall Street in Yarraville, with outbound and inbound portals positioned near the West Gate Freeway in South Kingsville. The outbound tunnel, already underway, is projected to take approximately 18 months to complete. TBM Vida achieved a breakthrough under Yarraville in February 2023, completing a 2.8-kilometre section.
Following the TBMs, work crews install road pavement, electrical systems, ventilation, and safety infrastructure. Up to 20 personnel can work inside each machine simultaneously, often in pressurized conditions up to 35 metres below ground. Operators undergo specialized hyperbaric training and may spend up to two hours decompressing after their shifts.
Meanwhile, a remarkable undertaking is unfolding above ground. A 116-metre-long launching gantry is constructing an elevated road over Footscray Road. Standing at 40 metres tall, it lifts and secures precast segments (manufactured in Benalla) using steel cable tensioning and grout injection to form spans. This innovative approach enables construction with minimal traffic disruption and preserves port access for freight.
Upon completion, the West Gate Tunnel will offer a vital alternative to the West Gate Bridge, enhancing travel times and redirecting over 9,000 trucks daily from inner-west roads.
Source: Infrastructure Magazine
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