Melbourne’s biggest tunnelling projects – how Hydraulics steals the show
Hydraulics has been fundamental to the tunnel boring operations of Melbourne’s largest infrastructure projects over the last few years. It’s enabled precise excavation through complex Melbourne ground conditions, where you need to avoid disturbing existing underground infrastructure.
We’ve taken a “deep-dive” into the role hydraulics, and Flotek have played in these massive projects.
Powering the Push!
Hydraulic cylinders supply the force necessary to push the Tunnel Boring Machine (TBM) forward, pressing the rotating cutterhead into rock and soil. In projects like the Metro Tunnel, West Gate Tunnel, and North East Link, where Flotek was lucky enough to play a part, Hydraulic systems were responsible for moving the massive Tunnel Boring Machine’s through 1000’s of tonnes of earth, advancing underground at a speed of approximately 9 meters per day.
Hydraulic thrust mechanisms actually adjust in real time to the resistance of the various types of earth, ranging from hard basalt under the Yarra River, to solid rock, to softer silt layers, ensuring continuous and controlled progress.
Cutterhead Operations
Hydraulic motors drive the massive rotating cutterheads on the front of Melbourne’s TBMs, with some cutterheads measuring 15.6m in diameter, weighing up to 100 tonnes. These motors provide the extreme torque required to break through rock, which is surprisingly much harder than concrete, maintaining a constant cutting pace while minimising vibration and disturbance above ground.
Precision Segment Erection
During tunnel construction, hydraulics also control the positioning and installation of curved concrete segments that form the tunnel lining. These systems allow for swift and accurate placement, ensuring a watertight and structurally sound tunnel. Nearly 43,000 such segments were placed in the North East Link tunnels alone, demonstrating the scale and precision made possible by modern hydraulic controls.
Material Transport and Support Systems
Other hydraulic mechanisms inside the TBMs power conveyors, facilitate the continuous removal of excavated material and relocation of segments. This efficiency supports the 24/7 operation needed to meet Melbourne’s ambitious project timelines.
Notable Projects in Melbourne
Metro Tunnel Project: Used four mix-shield (slurry) TBMs weighing over 1100 tonnes, each employing hydraulic systems for propulsion, cutting, and segment installation over 9 km twin tunnels.
West Gate Tunnel: Deployed the country’s largest TBMs—up to 15.6 m in diameter and 4000 tonnes, advanced by hydraulics through the city's west over multi-year continuous operations.
North East Link: Herrenknecht launched two state-of-the-art TBMs (“Zelda” and “Gillian”) in 2024, each relying on hydraulic power for digging Victoria’s longest tunnels under challenging conditions.
Major Sewer Projects: Specialized TBMs for sewer construction used hydraulic pipe-jacking systems to push pipes through deep ground, enabling trenchless installations at significant depths.
Suburban Rail Loop – start 2026
So eventually when our roads are cleared of construction works, and running smoothly, remember that Hydraulics, and Flotek, played an important part.
Safety, Reliability, and Innovation
Hydraulic systems offer smooth, controlled power delivery, crucial for safe operation in confined and pressurized underground environments. They are engineered for reliability to ensure minimal downtime over multi-year projects and provide the adaptability to tackle mixed and unpredictable ground conditions found beneath Melbourne. Advancements such as split-flow hydraulic pumps allow for precise adjustment of thrust across multiple cylinders, increasing stability and control.
German company, Herrenknecht were responsible for supplying most of the Tunnel boring machines in these projects.
Conclusion
In Melbourne’s major tunnel projects, hydraulics power everything from the Tunnel Boring Machine’s push, to the minute positioning of tunnel segments and support systems. By enabling continuous, precise, and robust operations, hydraulic technology remains a cornerstone of the city’s most complex and transformative subterranean infrastructure works.
