AUCKLAND CITY COUNCIL

MEDIA RELEASE

1 May 2007

Last test before Central Connector gets underway

A geotechnical investigation found out exactly how strong rock beneath Grafton Bridge’s foundations is and how much work needs to be done to meet modern earthquake standards proposed by the Central Connector’s design.

The bridge, when complete, will be able to withstand a one-in-one-thousand-year earthquake. To get it to that strength requires the installation of piles at the base of the main piers’ foundations, the strengthening of the piers internally by inserting new steel reinforcements, and retrofitting the bridge deck with carbon fibre reinforced polymer.

The foundation testing on Friday, 27 April, was done by some of New Zealand’s finest geotechnical engineers, led by Beca bridge specialist Will Pank.

“The job was an especially complex one because of the age of the bridge, its construction details and its location across major motorway links,” says Mr Pank.

Mr Pank is excited that he has had the opportunity to work on two of Auckland’s most interesting bridges – Grafton and the Harbour Bridge.

“The Grafton Bridge upgrade is a unique challenge because of its age and the type and condition of its foundations. The bridge was built in 1908 and held the world record for the longest spanning concrete arch at the time of its construction, so it is a unique design and with some additional strengthening it should be able to serve Aucklanders well into the future,” says Mr Pank.

“What makes this job challenging is the need to design strengthening that does not impact on the architectural heritage of the bridge and to build in resistance to earthquakes.”

The council has consulted with one of New Zealand’s premier specialists in bridge and geotechnical engineering in the design process, the objective being that the bridge remains a world class structure.

Friday’s borehole test was the last investigative procedure before the council begins constructing the biggest public transport initiative since Britomart in August.

The Central Connector will create a dedicated quicker bus route, reducing peak journey times by up to 14 minutes. The route will provide a rapid bus link from Britomart to Newmarket via Grafton Bridge. The bridge’s design has been future proofed so light rail can remain a transport option for the central city.

The main corridor is ready for construction, following an urban design review carried out late last year. The review has enhanced the initial design, incorporating improved safety, convenience and the attractiveness of the route.

Safer pedestrian crossings, new street lighting, upgraded footpaths and new street furniture will create a pleasant and effective route for the varied needs of the 65,000 weekday bus users says chairperson of the Transport and Urban Linkages Committee councillor Richard Simpson.

“This is the first time any major work will have taken place on Grafton Bridge since the 1930’s, so I am delighted to be part of this fundamental development. The testing is an important part of the project to ensure the future health of the bridge,” says Mr Simpson.

“If we want to build a great city for Aucklander’s and visitors to enjoy, we need to create better transport choices that provide real opportunities for pedestrians, cyclists, and all users of road and rail in our city,” says Mr Simpson.

Ends

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