Summer holidays: just the break needed for the NAaN grid upgrade

27 February 2013

It's been a busy start to the year on all fronts for Transpower's grid upgrade project to reinforce electricity supply into Auckland and Northland.

The North Auckland and Northland (NAaN) project involves installing underground cables between Albany and Pakuranga substations, connecting through Penrose substation and new substations being built at Hobson Street in Auckland CBD and Wairau Road on the North Shore. Work has been progressing over the last two years.

Project Director Paul Duffy says the team maximised its opportunity to work over the holiday period when traffic volumes are relatively low.

It was an approach that paid off along Fanshawe Street, Auckland's main arterial route into the CBD for all North Shore buses and thousands of commuters daily.

"We were aware of the potential disruption as we were restricting traffic to two lanes, which included opening the dedicated bus lane to general traffic. Months of planning and modelling were undertaken with Auckland Transport, the Auckland Motorway Alliance, Joint Traffic Operations Centre and the NZ Transport Agency to ensure we got it right, Paul Duffy said.

"We finished well ahead of schedule and managed to avoid what is often referred to as 'March Madness' by transport operators, when university students return and commuter and public transport numbers radically increase," he said.

Transpower has now entered the final stages between the Albany and Hobson Street substations. All cables have been fully installed between Albany and Wairau Road and are currently undergoing pre-commissioning testing. Shortly, cables will be installed under the Harbour Bridge and along the Northern Motorway to complete the northern route between the CBD and Albany.

Construction will be completed mid 1013 with commissioning later in the year.

Progress is also being made between Pakuranga and Penrose with work advancing along Ti Rakau Drive.

"Fortunately we are able to excavate trenches in the section between the Ti Rakau Bridge and the Pakuranga substation at night to minimise impact on traffic during the day. However, the rest of Ti Rakau Drive will need to be done during the day time due to the number of residential homes along this section of the cable route," Paul Duffy said.

"On all sections of the project we have been grateful for the support and tolerance shown by people living and working along the cable route", he said.

Update on substations

The two new Transpower substations being built at Hobson Street and Wairau Road to reinforce the power supply in Auckland's CBD and the North Shore respectively are also well advanced. The existing Vector facilities at these sites are being upgraded as part of the project.

Hobson Street Substation

The location of this new substation on a constrained urban site has posed a number of challenges for the project team but the new 220 kV building is now structurally complete with a planned September commissioning on target.

The project has involved constructing a new tunnel and four buildings to house the Transpower and Vector substations.

Over 120 workers across the various trades are on site daily to see the substation through to completion. Roofing steel has been installed on the Vector and Transpower buildings and the cable tunnels, transformer enclosure walls and vent building walls are now all structurally complete. 

Mr Ryall says during the early civil works old piles, chimney bases, tunnels and extensive mass concrete foundations were exposed revealing the sites historical linkage to the electricity industry.

"Generation plant for Auckland’s electrical trams were located here and more recently Vector’s distribution station."

Wairau Substation

Commissioning is in sight as the final stages of construction at the Wairau Road substation are completed. Project manager Brett Stark says although the project is in countdown mode there is still a lot of work to be done with nearly 50 people still working on the site.

A key milestone was achieved in December with the delivery of the 106.5 tonne 120 MVA capable transformer – once installed, the transformer weighed 160 tonnes. Since then, all seven bays of the GIS and interconnecting bus bars have been installed and the Albany cable circuit has been terminated and is currently being tested.

The remaining tasks involved with the GIS installation will be undertaken in the coming weeks, followed by months of testing.

The nocturnal delivery of the transformer from Manukau to Wairau can be seen here: