Sandvik Mining and Construction Australia has been awarded the contract to provide the majority of the roadheaders required for Sydney’s NorthConnex tollway tunnel project.
The contract represents the single largest order for Sandvik tunnelling roadheaders since it won the contract to supply the Sochi Olympic Park excavation in Russia over five years ago.
Thirteen of the 19 roadheaders required for the project are being supplied by Sandvik, including six MT720 units, six MT520 units and one MT620.
The MT720 is the largest of the three Sandvik models. It weighs in at over 135 tonnes and can bore a hole over 9 metres wide at its maximum digging width. The MT720 has been engineered to cut through hard and abrasive rock with a pressure rating of above 120 MPa.
The MT620 is its slightly smaller sibling, but still packs a punch with the same 300kW cutting motor as the MT720.
The six MT520 models ordered for the project are for smaller, more compact jobs. The MT520 features a modular design that offers more flexibility than the larger units, with different cutting heads easily swapped in and out as needed.
The tunnel work will be carried out by a 50-50 joint venture between two construction firms – Australia’s Lend Lease and France’s Bouygues. The partnership was originally formed to complete Melbourne’s East West Link before focus switched to the NorthConnex tunnels following East West Link’s cancellation.
The project is sponsored by the NSW Government, Transurban and the M7 Westlink Shareholders group.
When completed, the NorthConnex project will link the M1 Pacific Motorway at Wahroonga to the Hills M2 Motorway at West Pennant Hills, connecting Sydney’s north to the Orbital network and will form part of the National Highway route.
The scheme includes twin motorway tunnels running in each direction, with two lanes and a breakdown lane in each. The tunnels will be built with a capacity for three lanes in future, but will run with two at first.
The Lend Lease-Bouygues Joint Venture (LLB JV) determined that mechanical cutting using roadheaders was the most suitable excavation method for the project. LLB JV then selected Sandvik roadheaders for the job due to past experience and Sandvik’s support capabilities in Australia.
Sandvik roadheaders use electro-hydraulic power, which emits no fumes, the company says, adding that this makes them particularly suitable for urban tunnelling projects.
The use of Sandvik roadheaders for tunnel boring means underground chambers can be dug continuously without the need for explosives, the vibrations from which can cause structural damage on the surface.
The machines being provided for the NorthConnex project are controlled by PLC, an automated precision guidance system that allows for highly-accurate excavation and profile visualisation.
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