Melbourne Metro Tunnel
Victoria’s transformative Metro Tunnel project demanded ingenious engineering solutions to navigate complex site constraints whilst maintaining ambitious construction timelines.
The $11 billion Melbourne Metro Tunnel creates a new end-to-end rail line from Sunbury to Cranbourne/Pakenham, featuring twin nine-kilometre tunnels and five underground stations. This landmark infrastructure enables more than 500,000 additional passengers weekly to use the rail system during peak periods. The Cross Yarra Partnership consortium engaged ADG to provide critical construction engineering expertise across the Tunnel and Stations work package, requiring innovative temporary works solutions that balanced intricate site constraints with existing infrastructure protection whilst enabling seamless construction sequencing.
CONSTRUCTION VALUE
CONSTRUCTION SUPPORT
WORK PACKAGES DELIVERED
The project team dubbed ADG's tailored cradle design the 'swiss army knife of TBM cradles' - a multi-purpose solution that enabled the Melbourne Metro Project to progress seamlessly without construction delays whilst minimising impact on existing and future structures within the project site.
Managing Massive Machinery in Confined Spaces
Retrieving and relocating 600-tonne tunnel boring machines within restricted site boundaries near existing permanent structures demanded innovative solutions that minimised construction timelines whilst protecting surrounding infrastructure:
- Custom designed modular rail system enabling 180-degree rotation of seven gantry carriages (11 metres long, 130 tonnes each) within confined site space
- Retrieval cradle and stopper frame design allowing TBM to slide onto retrieval cradle for dismantling whilst enabling final tunnel segment construction
- Pulling frame and lug design facilitating movement of dismantled TBM pieces into lifting window
- Comprehensive inspection and certification of as-built structures ensuring structural integrity throughout relocation process
Innovative TBM Launching Solutions
Relaunching tunnel boring machines at ANZAC Station required sophisticated engineering that accommodated high support loads, maintained flexibility during installation and eliminated traditional formwork requirements within tight construction schedules. This included:
- False tunnel supports featuring unique screw jack arrangement with hinge mechanism enabling flexibility and tolerance during TBM componentry installation
- Bespoke transport cradle incorporating innovative grouting mechanism using lever system, eliminating formwork and underside access requirements
- Pushing frame design enabling TBM movement into break-in seal and final launching position
- Thrust frame installation and sequencing advice accounting for high support loads during launching operations
- Temporary works facilitating installation and removal of thrust frames and break-in seals, including stability assessments during construction and movement methodology
Multi-Purpose Cradle Innovation
Supporting 600-tonne tunnel boring machines through jacking, sliding and drive manoeuvres whilst minimising impact on existing and future structures required engineering solutions that delivered multiple functions without compromising structural integrity:
- Multi-purpose bespoke steel cradle design supporting TBM through jacking, sliding and drive manoeuvres to headwall
- Engineering design for cradle transport from lifting window and build site to launch area
- TBM assembly on transport cradle supporting sliding cradle during jacking manoeuvres
- Gantry ramp design for TBM backup gantries ensuring smooth operational transitions
- Rail section switching incorporating for-purpose pieces supporting transverse movement directions, optimising U-turn execution within limited space
ADG provided comprehensive construction engineering expertise across 120+ work packages spanning the project’s 2018-2025 timeline, delivering round-the-clock support during critical construction phases. The Melbourne Construction Services team developed innovative temporary works solutions that enabled continuous project progress whilst protecting existing infrastructure.
The centrepiece achievement involved designing and developing a multi-purpose bespoke steel cradle that revolutionised tunnel boring machine handling across the project. This versatile solution carried 600-tonne TBMs through complex jacking, sliding and drive manoeuvres, earning recognition from the project team as the ‘swiss army knife of TBM cradles’ for its adaptability and effectiveness.
TBM Retrieval at South Yarra encompassed pulling and rotating seven massive gantry carriages within severely confined site spaces using custom-designed modular rail systems. The team engineered retrieval cradles and stopper frames enabling seamless TBM dismantling whilst allowing final tunnel segment construction, alongside pulling frames facilitating movement of dismantled components into lifting windows.
TBM Relaunch at ANZAC Station required sophisticated secondary structure engineering enabling precise launching sequencing methodology. Solutions included false tunnel supports featuring unique screw jack arrangements with hinges providing critical flexibility during installation, and innovative grouting mechanisms incorporated into transport cradles using lever systems that eliminated traditional formwork requirements and underside access needs.
Structural Innovation and Coordination delivered pushing frame designs enabling TBM movement into break-in seals and final launching positions, thrust frame installation guidance accounting for high support loads, and comprehensive temporary works facilitating installation and removal operations. The team provided stability assessments throughout construction phases and developed movement methodologies ensuring seamless coordination across all work packages.
This integrated approach minimised impact on existing and future structures, reducing requirements for additional checks and repairs whilst maintaining ambitious construction schedules. The purpose-driven solutions enabled the Cross Yarra Partnership to progress works ahead of schedule, demonstrating how responsive engineering excellence delivers tangible value on Australia’s most significant transport infrastructure projects.
Risk Mitigation
Complex site constraints near existing permanent structures and utilities demanded proactive risk management throughout TBM retrieval and relaunch operations. ADG developed comprehensive temporary works solutions incorporating stability assessments, structural inspections and certification processes that protected surrounding infrastructure whilst maintaining construction momentum. The multi-purpose cradle design minimised potential impacts on existing and future structures, reducing requirements for additional checks and repairs whilst enabling 24/7 construction support during critical phases.
Delivering 120+ work packages across a seven-year timeline required exceptional coordination and responsive engineering support. The Melbourne Construction Services team provided continuous collaboration with specialist stakeholders, developing solutions that enabled seamless integration between new and existing infrastructure. Round-the-clock availability during critical construction phases ensured immediate technical support when required, whilst comprehensive inspection and certification processes maintained quality standards throughout all temporary works installations.
Technical Innovation
The bespoke steel cradle represented significant engineering innovation, incorporating unique features that addressed multiple construction challenges simultaneously. Custom-designed modular rail systems enabled precise machinery movement within confined spaces, whilst innovative grouting mechanisms eliminated traditional formwork requirements. Unique screw jack arrangements with hinges provided critical flexibility during installation, and for-purpose rail switching components optimised movement within limited site spaces. These purpose-driven solutions demonstrated how intelligent engineering creates value through practical innovation.
Purpose-driven engineering solutions enabled the Cross Yarra Partnership to maintain ambitious construction schedules whilst managing complex site constraints. The versatile cradle design streamlined TBM handling operations, eliminating delays that traditional approaches might have created. Custom rail systems and innovative mechanical arrangements reduced installation time and complexity, whilst comprehensive sequencing advice ensured smooth transitions between construction phases. This efficiency translated directly into schedule adherence and cost management across the broader project timeline.
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