Alice, the world's 10th largest tunnel boring machine, is due to finish half her journey next month. Steve Mutton, NZ Transport Agency's acting highways manager, says the first tunnel will be finished soon so the massive machine can begin the second tunnel.
"On her arrival at Waterview in September, Alice will be turned around over the following three months and re-launched on her southbound journey early next year, building the second (northbound) tunnel as she goes," NZTA says.
On August 4, John Burden, project manager for the Well-Connected Alliance, gave an update on progress of the tunnel boring machine. "The TBM is about 1500m or two-thirds of the way to Waterview and approximately 750 tunnel lining rings in place."
The agency says construction of the two tunnels will be finished at the end of next year, when they will be fitted out with the services needed to operate them.
"These include ventilation fans, communication systems and fire protection. Sixteen cross passages -- one every 150m -- connecting the twin tunnels will also be built. The entire project, which includes the motorway connections either end of the tunnels, is due to be opened in early 2017."
The Waterview Connection completes Auckland's Western Ring Route. The alternative to the SH1 Southern and Northern Motorways will be 47km long between Albany and Manukau. The Western Ring Route will improve city and regional transport connections, and is identified by the Government as a Road of National Significance because of its importance to New Zealand's economy.
The Waterview Connection project is being delivered by the Well-Connected Alliance which includes the Transport Agency, Fletcher Construction, McConnell Dowell, Parsons Brinckerhoff, Beca Infrastructure, Tonkin & Taylor and Japanese construction company Obayashi Corporation. Sub-alliance partners are Auckland-based Wilson Tunnelling and the Spanish tunnel controls specialists SICE.
Herald readers asked if there were any plans to open at least the first tunnel once it was finished, rather than waiting for both.
But they were told that as much as NZTA would like to be able to deliver some of the benefits of the Waterview Connection project early, it was not possible for a number of reasons, including that ramps and connections between the Northwestern and Southwestern motorways, and other improvements along the Northwestern Motorway, need to be completed as part of the huge job.
Rory Bishop, construction manager of McConnell Dowell Constructors in the Well-Connected Alliance says speed underground depends on many different factors including the density of the ground being dug, sharpness of the teeth on the tunnel borer or whether equipment such as cables needed to be changed.
McConnell Dowell has a $400 million share of the job and Gwyn Jones, McConnell Dowell's Melbourne-based tunnel and underground project manager, says Alice is fast compared to the far smaller tunnel-boring machines that built the new Singapore Downtown Line 2 MRT where he has worked.
Progress on that A$3.6 billion, 16km-long, 6.6m diameter train tunnel was around only 140m/month in extremely hard conditions but even in soft conditions, only 250m/month.