ADG’s outstanding bespoke cradle design has been effective in achieving time and cost savings for the Melbourne Metro Tunnel project, enabling construction works to move ahead of schedule.







project details


Melbourne, Victoria


Cross Yarra Partnership (CYP) — comprising Lendlease, John Holland, Bouygues Construction, John Laing and Capella Capital

Project timeline


lead contact
Matthew Obst

Practice Manager - Melbourne

Key Expertise

The Melbourne Metro Tunnel is a $11 billion project which will create a new end-to-end rail line from Sunbury to Cranbourne/Pakenham, with five new underground stations to enable more than 500,000 additional passengers per week to use the rail system during peak periods.

As part of a multi-billion-dollar availability based Public Private Partnership (PPP), the CYP consortium sought to design and construct twin nine-kilometre tunnels and five underground stations as part of the Tunnel and Stations work package, challenging site constraints and delivering purpose-driven practices to enable the proposed construction sequencing.
The ADG project team was required to work within intricate site and equipment constraints, manage specialist stakeholders to develop solutions that could enable works, and allow for consideration of the interface between new and existing infrastructure, with a site close to existing permanent structures and utilities.


ADG was consulted by the CYP consortium on more than 120 separate work packages, including construction engineering services, civil engineering and structural designs.
Works have ranged from provision of logistical work areas, safety and access platforms and secondary structures to the construction, launching, retrieval and demolition of the tunnel boring machines (TBM), that enabled tunnel works to be established and progressed.

Led by the Melbourne Construction Services team, assistance provided included:

Retrieval of TBMs at South Yarra and gantry crossover

  • Pulling and 180-degree rotation of seven gantry carriages (approximately 11 metres long and 130 tonnes) within a confined site space using a custom designed modular rail system
  • Switching of rail sections (including design of for-purpose pieces to support movement in transverse directions) to optimise and facilitate U-turn in limited space
  • Retrieval cradle and stopper frame design to enable the TBM to slide onto the retrieval cradle to be dismantled, and to allow the final tunnel segments to be constructed
  • Pulling frame and lug design to move the dismantled TBM pieces into the lifting window
  • Inspection and certification of as-built structures.

TBM relaunch at Anzac Station

  • Engineering and design of secondary structures to enable sequencing methodology for launching the TBM for tunnelling
  • Engineering design for false tunnel supports, including unique screw jack arrangement with a hinge to enable flexibility and tolerance during the installation and placement of the TBM componentry
  • Engineering design for the cradle to transport TBMs from the lifting window and build site to the launch area
  • Incorporation of a unique grouting mechanism into the TBM cradle using a lever system, eliminating formwork and access requirements to the underside of the cradle
  • TBM assembly on the transport cradle to support sliding cradle during TBM jacking manoeuvres
  • Pushing frame design to enable the TBM to move into the break-in seal and into its final launching position
  • Thrust frame installation and sequencing advice, incorporating consideration of the high support loads caused by launching
  • Temporary works to facilitate installation and removal of the thrust frames and break-in seals, as well as stability assessments during construction and movement methodology
  • Gantry ramp design for TBM backup gantries.

To date, ADG has provided the critical structural temporary works, enabling the retrieval of TBMs at South Yarra followed by the reassembly and relaunch at Anzac Station, with 24/7 support during construction works. This was achieved through the design and development of a multi-purpose, bespoke steel cradle that was used to carry the 600 tonne TBM during jacking, sliding and drive manoeuvres on its way to the headwall. The unique, for-purpose design has also been effective in minimising impact on existing and future structures, reducing the need for additional checks and repairs.

“Dubbed by the project team as the ‘swiss army knife of TBM cradles’, our tailored cradle design has allowed the Melbourne Metro Project to go ahead seamlessly without delays to construction timelines, also minimising the impact on existing and future structures within the project site.”

- Matthew McCormick, ADG Senior Construction Services Engineer
the Team
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