The Northern Gateway Alliance (NGA) is today celebrating the breakthrough of the southbound tunnel excavation at Johnstone’s Hill as part of Transit’s State Highway 1 Northern Motorway extension project (ALPURT B2).

Tunnelling began in February this year and a total of 333 metres were excavated to complete the “top heading” or top half of the first of the twin tunnels. The base section of the tunnel, or “bench” will eventually be excavated using earthmoving equipment. In the meantime the partially excavated tunnel will be used to provide access to the southern portal area for construction of the northern abutment of the Waiwera Viaduct.

"This is another piece of the ALPURT B2 jigsaw that's now in place on this complex and exciting project,” said NGA Project Director, Robert Jones. “The breakthrough in the southbound tunnel is a culmination of an enormous amount of effort the alliance team of tunnellers, geotechnical engineers and designers working closely together on a daily basis. The work has proceeded very smoothly with the minimum of fuss and is right on schedule and budget," he said.

Each tunnel is being excavated in two halves starting with the top half, a five metre high top heading which is excavated using a refurbished Mitsui Miike S200MA Roadheader machine. The remaining four and a half metre bench is then excavated using earthmoving equipment. Temporary reinforcing is added to the tunnel every 1.5 metres. Four metre long rock bolts are driven into the walls of the tunnel, creating a supporting arch which is then sprayed with a coating of reinforced shotcrete.

Excavation is followed by a year of lining works and another six months for fit-out for the tunnels, which will stand 15 metres apart, each measuring 345 metres in length, 12 metres in width and nine metres in height.

Once complete the twin tunnels will be New Zealand’s most sophisticated in their fit-out, the deluge fire suppression system being installed is a first for tunnels in this country. They will be concrete lined, fully lit, have traffic control systems and ventilation fans. The tunnels will be curved horizontally and vertically to align them with the Waiwera Viaduct to the south and the existing SH1 to the north.

Completion of the Johnstone’s Hill tunnels is expected in late 2007 or early 2008, the motorway extension is due for completion in mid-2009.

The Northern Gateway Alliance, which is project managing, designing and constructing the motorway, comprises Transit New Zealand, Fulton Hogan, Leighton Contractors, URS New Zealand, Tonkin & Taylor and Boffa Miskell. The Alliance has brought in two tunneling experts with international experience to help with the project.

30 September 2004

Media Release

Northern Gateway Alliance to establish ALPURT B2 project office.

Work will commence  in October on a project office for the proposed ALPURT B2 motorway between Orewa and Puhoi.

Noting that construction of the motorway itself remained subject to Ministerial approval and an Order in Council, Transit New Zealand’s Regional Manager Wayne McDonald said there were a number of benefits in establishing an on-site presence during the planning phase of the project.

“Establishing the office will be of significant benefit to the design process and our construction methodology planning,” said Mr McDonald.

“It will provide the design team with better access to the proposed route and we will be able to supervise on-site work, including ongoing research initiatives, trials and environmental mitigation activities, much more closely.”

“If Ministerial approval to toll is received, having an office already on site will also help us make a quick start to construction, which is very important from a cost perspective.”

The Northern Gateway Alliance, which is project managing and designing the proposed toll road, plans to locate the office near the roundabout at the current termination of Auckland’s northern motorway at Grand Drive, Orewa.  Access to the office will be via a road to be constructed off the roundabout.

The work, which is due to start on 4 October, includes the construction of an access road, car-park, building platform and associated drainage and facility services installation.

Mr McDonald said that prior to commencing work on the project office the Alliance would put a range of related environmental protection measures in place, including silt fences.  Construction work on the office itself will begin in three or four weeks.

The Northern Gateway Alliance comprises Transit New Zealand, Fulton Hogan, Leighton Contractors, URS New Zealand, Tonkin & Taylor and Boffa Miskell.  

ENDS

For more information: Catherine Etheredge, Ph 64 9 309 1494, 64 27 276 9172

You may ask - Who is in the Northern Gateway Alliance?

The Northern Gateway Alliance was formed in March 2004 to design and build the Northern Motorway Extension between Orewa and Puhoi, and to complete the procedures necessary to toll the route. Seven organisations make up the Alliance, and each member plays a critical role in ensuring the project is innovative, efficient and cost-effective.

The Alliance is a functional extension of Transit New Zealand, New Zealand's state highway manager. The other Alliance participants are Fulton Hogan, Leighton Contractors, URS New Zealand, Tonkin & Taylor, Boffa Miskell and sub-Alliance participant VSL.

Dedicated staff and resources from each of the participant organisations have been brought together into one team, operating at a single office, for the duration of the project.

Grant will be able to keep Association members up-dated on progress and any areas where we are able to have our say.