Microtunnelling, Pipe jacking, Tunnelling

NZ TBM ready for tunnelling

The tunnel boring machine’s (TBM) huge cutter was recently officially switched on by the Minister of Transport, Hon. Gerry Brownlee.

After two ceremonial rotations of the cutter head, the machine was shut down for final preparations.

The TBM, dubbed “÷Alice’, will excavate the twin motorway tunnels for the $A1.4 billion project.

The TBM has an outside diameter of 14.46 m, which makes it the 10th largest tunnel boring machine in the world.

The machine will bore two tunnels, 2.4 km long and both wide enough for three lanes of traffic. The tunnels will connect the Northwestern and Southwestern Motorways (State Highways 16 and 20) and complete the Western Ring Route, a motorway alternative to State Highway 1 through central Auckland.

“It’s an exciting and huge milestone for New Zealand’s largest ever roading project,” said Transport Agency Highways Manager for Auckland and Northland Tommy Parker.

“It’s taken 18 months and 2.5 million challenging work hours in some very demanding conditions to get everything ready, and when we’ve completed our final run-through, Alice will have her first encounter with real dirt next week.”

Mr Parker congratulated the Well-Connected Alliance – which is constructing the Waterview tunnels – for completing the project’s most significant milestone “bang on target.”

The Alliance is made up of New Zealand Transport Agency, Fletcher Construction, McConnell Dowell Constructors, Parsons Brinckerhoff, Beca Infrastructure, Tonkin and Taylor, and Japanese construction company Obayashi Corporation.

“The innovation and practise already in use on the construction site is attracting a lot of international attention – this is a New Zealand project on a world scale. Overseas interest in our project is reflected by our guests here today, which include senior executives from leading infrastructure companies in Germany, Japan and China,” said Mr Parker.

The TBM has to first push herself through a circle of soft concrete covering the tunnel portal before it starts excavating dirt. It will excavate down to a depth of 45 m, travelling at a top speed of 8 cm a minute. It will take a year to travel north from Owairaka to Waterview, where the machine will be dismantled, turned around, and re-assembled to excavate the second tunnel.

It will take two years to excavate both tunnels. By the time the TBM finishes its journey, it will remove more than 800,000 cubic metres of dirt – enough to fill 320 Olympic-size swimming pools. The soil will be trucked to a disused quarry at Wiri in south Auckland.

After excavation, the twin tunnels will be fitted out with lighting, ventilation and safety equipment before being opened to traffic in early 2017.

The Western Ring Route – a 47 km-long motorway between Albany and Manukau – is one of the Government’s seven roads of national significance, and Mr Parker says the Waterview Connection is the “last piece in the ring route puzzle” that when completed will help develop economic growth for Auckland and New Zealand.

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