Auckland Waterview Connection project update

By: Jenny Pretorius, NZ Transport Agency, Photography by: NZTA

Auckland Waterview Connection Auckland Waterview Connection
Auckland Waterview Connection Auckland Waterview Connection
Auckland Waterview Connection A segment being erected. Auckland Waterview Connection
Auckland Waterview Connection The tunnel portal of the first of the twin tunnels. In the top right corner of the image runs the 4.8m-high elevated conveyor belt that carries spoil from the tunnel face to the spoil handling building, situated 750m from the tunnel portal. Auckland Waterview Connection
Auckland Waterview Connection A trailer carrying the 10 segments that makes up a single lining ring weighing about 130T. Auckland Waterview Connection
Auckland Waterview Connection On board Alice: The TBM operating pressure is six bar, the maximum face pressure expected is 4.5 bar. Auckland Waterview Connection
Auckland Waterview Connection Auckland Waterview Connection
Auckland Waterview Connection Auckland Waterview Connection
Auckland Waterview Connection The cutting head: in the tunnelling phase, hydraulic thrust cylinders apply pressure of up to 22,800 tonnes to push the cutting wheel against the tunnel face. Auckland Waterview Connection
Auckland Waterview Connection The special 68m-long lifting gantry installing the 3.7m-wide, 2.2m-high culvert that sits on the floor of the main tunnel and will carry the services required to operate the tunnel. Auckland Waterview Connection
Auckland Waterview Connection Auckland Waterview Connection
Auckland Waterview Connection Auckland Waterview Connection

The NZ Transport Agency's Waterview Connection project in Auckland is moving along at a clipper rate. On the southern end, almost half of the first tunnel's 2.4-kilometre length has been excavated and on the northern end, the interchanges to connect SH16 to the tunnels are taking shape.

Tunnel borer machine (TMB) Alice has resumed operations building the southbound tunnel of Auckland's Waterview Connection, following a short scheduled service break in May.

This tunnel is the first of the twin motorway tunnels that will connect Auckland's Northwestern and Southwestern motorways. Each tunnel will carry three lanes of motorway traffic. Work is advancing well on both the south and north sides of the Waterview Connection project.

Progress on the south side

Alice is working in a northbound direction, constructing the tunnel that will carry southbound traffic. Starting work in November, 2013, she has now built 920 metres of the 2.4-kilometre-long tunnel, including simultaneously installing two-metre-wide concrete rings that will line and support the structure. She is working 40 metres below ground and the aim is to construct around 14 metres of tunnel per day on average.

Alice is expected to break through into daylight at the Waterview portal of the tunnel in late September. At that time, Alice will be turned around to be relaunched for her journey south, so she can build the northbound motorway tunnel.

Stefan Hanke, construction director for the Well-Connected Alliance, explains that to do this, the TBM will be moved onto a heavy-duty steel cradle located in the trench. The TBM and cradle will then be moved sideways and turned around 180 degrees into its northbound tunnel start-up position using strong hydraulic jacks. This process will take three months. The expectation is that Alice will start her return drive to Owairaka in early 2015. Supplies for and spoil from the northbound tunnel will be continued to be transported via the southbound tunnel.

Following closely behind Alice, a special 68-metre-long lifting gantry is installing a 3.7-metre-wide and 2.2-metre-high culvert that sits on the floor of the main tunnel and will carry the services required to operate the tunnel. The culvert will run below the completed motorway and will carry the cables for the ventilation, communication, fire detection, and lighting systems required to operate the tunnels after they open to traffic in early 2017.

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Alice paused earlier this month for replacement of the steel brushes that seal the TBM against inflow of cement grout associated with the installation of the tunnel lining. These brushes are located within the TBM shield and because they seal the machine from the surrounding ground, they are subject to wear and tear. Hanke expects the brushes will be replaced again during the TBM turnaround.

Community support remains at a high level. Alice is attracting huge interest locally, nationally, and internationally. She has her own Facebook page with nearly 3000 followers and has featured in a number of international construction and tunnelling publications. Youtube video clips posted by NZ Transport Agency showing her progress continue to generate a high level of viewing.

Concerning other work, construction of the motorway alignment linking the tunnels and SH20 has been completed. During construction, this link provides a direct link from the construction site to the motorway for heavy vehicles — in particular the more-than-100 vehicles a day that remove spoil excavated from the tunnels.

Other key enabling tasks have included the construction of a motorway overpass to take Richardson Road over the motorway; construction of an overpass above Oakley Creek (Auckland's longest freshwater creek); realignment and improvement of other sections of the Oakley Creek; relocation of a major Watercare sewer away from the motorway alignment; and construction of stormwater treatment ponds.

Progress on the north side

At the Waterview end, the northern tunnel portal is being prepared to the west of Great North Road. The trench approach to the northern tunnel portals has now been completed. The trench was built using the diaphragm wall to support the trench wall. The sandy soil was tricky to work with. The solution was to pump bentonite from the site's own plant into the trench excavation hole to condition the sandy soil and make it easier for the excavator to remove the spoil.

Nearby, a large project within a project is underway to build the interchange ramps to link the Northwestern and Southwestern motorways when the tunnels open. This work involves the construction of four ramps over existing motorways and local roads, comprising a total of 1.7 kilometres of new viaduct structures. The interchange will also provide direct motorway connection between Auckland CBD and Auckland International Airport and with the city's developing areas in the southwest and northwest.

The new interchange ramps require construction of 53 bridge spans comprising 54 columns founded on bored piles, 44 crossheads, three table tops, and 279 Super-T beams each up to 36 metres long. The alliance is using a purpose built 100-metre-long self-launching girder to place the Super-T beams. Viaduct construction started in 2013 and the first of the four ramps was completed in May this year.

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.

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It's in the genes

When the Waterview Connection was still a twinkle in Aucklanders' eyes, construction director Stefan Hanke was already building tunnels everywhere he could find a client wanting to connect A to B through a stretch of ground.

Hanke has come to the Well-Connected team via a raft of tunnelling projects worldwide. You could say that tunnelling is in his blood, as his father was involved in many tunnelling projects and he spent many school and university holidays visiting and working on construction sites. "Being underground felt always felt natural," says Hanke.

After studying civil engineering at university in Munich, Hanke went straight to his first tunnelling project in Lesotho, a mountain kingdom in the heart of South Africa. That began an exciting profession being involved in large infrastructure projects around the world.

He worked on the Hong Kong airport railway where he was in charge of tunnel construction on Lantau Island, before returning to Germany, where he had the opportunity to be involved in the construction of two of the countries longest and largest highway tunnels. Next Hanke moved to Sydney, where he worked on the M5 east tunnel, and then to Austria to manage the construction on twin highway tunnels near Vienna.

Hanke was also involved in the delivery of the Clem7 tunnels in Brisbane and after spending time in Germany and London, he joined McConnell Dowell to work on the Waterview project here in Auckland.

"The Waterview Connection project is impressive and we have a great team delivering this challenging infrastructure. Once completed, the Waterview Connection will provide a fully-integrated link between SH20 and SH16 that is efficient and safe to use, and I am confident it will improve the quality of life for many people in Auckland," he says.

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