Syndey Metro City & Soutwest – TSE .
Contact grouting, concrete surface repairs, structural crack injection and polyurethane injection to treat groundwater ingress in segmentally and cast in-situ lined tunnels, station boxes and shafts.
The Sydney Metro – City & Southwest Tunnel and Station Excavation (TSE) project was delivered by the CPB Contractors, John Holland, and Ghella Joint Venture. It involved the construction of twin 15.5-kilometre tunnels between Chatswood and Sydenham, passing beneath Sydney Harbour and through the heart of the CBD. The scope also included the bulk excavation of station boxes at Crows Nest, Victoria Cross, Barangaroo, Martin Place, Pitt Street, and Waterloo, as well as dive structures at Chatswood and Marrickville.
Spanning a vast section of Sydney, this project encountered a wide range of geological conditions, including complex works beneath Sydney Harbour. With over 99,000 precast concrete segments required to complete the tunnel alignment, and numerous interconnected underground structures, the project faced consistent challenges related to groundwater ingress. Minor damage to precast tunnel segments—particularly at segment edges and vacuum erector cone pockets—was also observed during TBM operations.
Direct Inject was engaged to deliver specialised concrete remediation and leak-sealing services across multiple elements of the project. Our scope included treatment of defects and water ingress within the segmentally lined tunnels, cast in-situ cross passages and crossover caverns, as well as within the structural elements of station boxes and dive structures.
Our works involved a combination of polyurethane and acrylic gel injection techniques, along with concrete repair and surface restoration methods to ensure long-term performance and watertight integrity across critical interface points. Our flexible deployment model allowed us to respond to evolving site priorities and emerging conditions throughout the delivery phase.
During the delivery phase, our works were performed in a highly active construction environment, often during concurrent TBM excavation, segment placement, invert construction, and structural lining of the cross passages
Following completion of the project and its opening to the general public, Direct Inject has worked closely with this client to coordinate access and ensure our works proceed safely and efficiently during limited access windows, typically during night shifts or planned engineering shutdowns. Our team’s ability to mobilise quickly and operate in confined, high-risk settings has been essential to maintaining program momentum while delivering precise, high-quality outcomes.
