Tunnelling on New Zealand’s largest roading project – the NZ Transport Agency’s Waterview Connection in Auckland – will stop for two to three weeks on Monday (5 May) for essential maintenance work on Alice, the project’s huge tunnel boring machine (TBM).
Hundreds of steel fibre brushes installed on the shield (front section) of the TBM need to be replaced. The brushes help to form a waterproof seal as the concrete segments that line the tunnel are lifted into place by Alice as she journeys underground.
The NZ Transport Agency’s Group Manager for Highway and Network Operations, Tommy Parker, says replacement of the brushes was expected sometime during Alice’s 2.4km journey from Owairaka and Waterview to build the first of the twin tunnels.
“Tunnelling on this scale is a complicated task, and some wear and tear on the machine is inevitable. We decided it would be prudent to replace the brushes now, before we possibly encounter more onerous groundwater conditions later in Alice’s journey.”
Mr Parker says tunnelling is continuing until Monday and Alice’s progress to date has been excellent, with approximately 800 metres of tunnel now constructed. About a third of the 12,000 concrete segments that form the southbound tunnel’s lining have been erected.
“The maintenance work on the steel fibre brushes will not affect other construction work in the tunnel. In fact, we can use the time to make faster progress on the concrete service culvert which is being built behind Alice.”
The culvert will carry the services needed to operate the two completed tunnels, which are due to open in early 2017.
Mr Parker says, however, that the need to replace the brushes means Alice may now “break-through” at Waterview in late September, two to three weeks later than was originally planned. She and her trailing gantries will then be turned around over the following three months, ready to begin building the second tunnel from Waterview to Owairaki.
“Given the enormous difference this project is going to make for Auckland, it is worth taking the time we need to get everything right,” Mr Parker says.
The twin tunnels, both 13.1m in diameter, are being constructed to connect Auckland’s Southwestern (SH20) and Northwestern (SH16) motorways as part of the city’s Western Ring Route, one of the Government’s flagship Roads Of National Significance (RONS). Each tunnel will carry three lanes of motorway traffic.
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 Spanish tunnel controls specialists SICE.
For more information please contact:
Auckland/Northland Media Manager
NZ Transport Agency
T: 09 928 8720
M: 027 213 7616