Waterview Connection project accepts 14.5m diameter TBM26 March 2013
The start of tunnelling on the NZ Transport Agency's (NZTA) landmark Waterview Connection project in Auckland has moved a step closer with the agency's Well-Connected Alliance formally accepting the machine it will use to construct the twin 2.5km-long tunnels, NZTA stated earlier this month.
NZTA announced that the 14.5 diameter machines is the world's 10th largest TBM to be built worldwide. According to the agency it has been designed specifically for the unique ground conditions on the USD 1.16bn Waterview Connection - the biggest transport construction project in New Zealand's history.
The handover earlier this month marks the completion of 14 months of design, build and testing of the giant machine. It will now be dismantled for shipment to New Zealand and is due to arrive in Auckland in July before being reassembled at the project's southern tunnel portal to begin tunnelling in October.
"The size of this project and the size of the tunnel boring machine are both on a scale the likes of which we have never seen before in New Zealand," said Tommy Parker, NZTA's state highways manager for Auckland and Northland. "Since mid-2012 we have been preparing a trench that will not only form the southern tunnel approach, but provide the TBM's launch pad. This requires us to excavate to a depth of 30m, initially, drilling and blasting through a 15m thick layer of very hard volcanic rock."
To construct two 2.5km tunnels, the TBM will pass beneath rock and tunnel through the softer clays of the East Coast Bay Formation. It is expected to take a year to complete the first tunnel, with the TBM due to emerge just beyond Great North Road in Waterview where work is already under way to prepare for its arrival and turnaround for the return journey.