Sydney Metro West – CTP BURWOOD .

As part of the Sydney Metro West project, the Central Tunnelling Package (CTP) is being delivered by the Acciona Ferrovial Joint Venture (AFJV). This package includes the construction of twin 11-kilometre tunnels between The Bays and Sydney Olympic Park, as well as the bulk excavation of five station boxes at Sydney Olympic Park, North Strathfield, Burwood North, Five Dock, and The Bays.

At Burwood North, the station box includes two cast in-situ nozzle enlargements located at the eastern headwall. To accommodate a secondary cast in-situ thickening layer above the tunnel axis, concrete needed to be removed to provide sufficient space within the minimum clear opening and to properly prepare the concrete surface to ensure proper bonding of the new overlay.

Direct Inject was engaged to carry out precision surface preparation works within one nozzle enlargement. Using hydro-demolition, the internal face of the nozzle was broken back and scabbled to a max depth of 70mm to achieve a minimum distance from the theoretical minimum clear opening. The nozzle geometry comprised two radii, approximately 9 metres and 6 metres respectively. To ensure a consistent and controlled finish, Direct Inject designed and fabricated a custom mobile scaffold-mounted guide rail system tailored to the nozzle’s curved profile. This rail was paired with the Aqua Cutter Ergo-go robotic system, enabling accurate, hands-free operation to an area with restricted access. Our team worked collaboratively with our client’s survey team to generate benchmarks and offsets that allowed for efficient and real-time checks of the tunnel profile as works progressed.

Due to the high-risk nature of ultra-high pressure water jetting, works were carried out in isolation from other trades. A 5-metre-high scaffold access platform was erected by AFJV, upon which our bespoke guide rail system was installed. This setup allowed our team to execute the hydro-demolition works safely and efficiently within a controlled environment.