Alice, the giant Tunnel Boring Machine (TBM), is back at work after a planned mid-winter maintenance break and has passed the halfway mark on the second leg of her deep journey underground at Auckland’s Waterview Connection project.
The TBM has constructed 1400 metres – 58% - of the project’s second 2.4km-long tunnel between the suburbs of Waterview and Owairaka to connect the city’s Southwestern and Northwestern motorways.
“The project team is very happy with progress, and we’re on track for a breakthrough in mid-spring,” says the NZ Transport Agency’s Highways Manager, Brett Gliddon.
Alice began excavating the first of the twin motorway tunnels at Owairaka in November 2013, arriving at Waterview last September. After the Waterview Connection’s successful operation to turn the TBM 180 degrees, it began its second drive – back to Owairaka - last April.
The TBM resumed work this week after a 5 day break to replace hundreds of steel fibre brushes on its shield or front section. The brushes help to form a waterproof seal when the concrete tunnel segments are lifted into place. There was a similar shutdown last year during the TBM’s first drive.
“It’s inevitable that there will be some wear and tear on the TBM given the scale of the project and the size of the tunnels we are constructing,” Mr Gliddon says.
Alice, which is the world’s 10th largest TBM, is averaging about 16m progress a day.
“She’s operating consistently. With the experience gained from the first drive, we’re very happy with her underground passage,” Mr Gliddon says.
The second tunnel will carry 3 lanes of northbound traffic towards the Great North Road Interchange. The first tunnel, completed last year, will carry traffic towards Auckland International Airport and further south.
Other work underway in the tunnel includes construction of the services culvert – a tunnel within a tunnel – which will carry electrical equipment to operate both tunnels and the backfilling operation before asphalt is laid for the new highway. Excavating the 16 cross passages connecting the two tunnels is underway, and the mechanical and electrical fit-out of the main tunnels is about to start.
The entire project, which includes construction of the motorway-to-motorway Great North Road Interchange, 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 47 kilometres 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 Spanish tunnel controls specialists SICE.