Claimed to be the largest single span reinforced concrete bridge in the world.
During Arthur Myers’s term as mayor, Auckland had a population of 60,000 people.
He predicted [correctly] that the population would double in 20 years time but few believed this.
Many thought that the city would never grow large enough to pay for such a massive piece of engineering as a bridge across Grafton Gully, from ridge to ridge. A loan was taken out to pay for it, and this raised concerns that it would become a burden to successive generations of ratepayers.
Myer’s vision for a four lane bridge met opposition inside Council and it was eventually built as a two lane viaduct.
Regarded as a waste of ratepayers’ money, many people called it “Myers Folly” for years.
Call the Aussies
Grafton Bridge was designed and built by an Australian firm, The Ferro-Concrete Company of Australasia Ltd. The bridge took two and a half years to build, and was opened in April 1910. It was claimed to be the biggest single span reinforced concrete arch bridge in the world at that time.
The bridge is 296m long. It is designed with a central span supported on parallel twin arches. The central span is 97.6m wide, rising 25.6m above the abutments and reaches a height of 43.3m above the valley floor.
Lots of wood: The timber formwork for the main arch consisted of 400,000 super feet (943 cubic metres ) of West Australian jarrah and Oregon pine. This massive amount of water- and rot-resistant timber was specially imported at great expense.
Difficulties arose for the Ferro-Concrete Company. The site, a steep-sided bush clad valley, proved more difficult than expected, with a combination of intractable clay and underground movement of water.
There was also trouble with the complexity of the formwork and getting it in place. All this work had to be done by hand - the photographs do not show the use of cranes or hydraulic lifts.
Concrete for the main arch: The pouring of concrete for the main arch took 13 days. All the 1200 tons of concrete for this project was mixed by hand and transported by wheelbarrows.
Going bust in the middle of it
Halfway through construction the Ferro-Concrete Company was declared bankrupt.
This was because of a contract clause which said that “…no progress payments should be made on the arch span till it is completed and tested.”
It is uncertain whether this clause had originated with Professor Moersch (a German expert on reinforced concrete construction, who had approved the bridge specifications) or within the City Council, but it led to devastating consequences for the Ferro Concrete Company.
Usually progress payments are made to a builder as each major segment of a project is completed and signed off.
On the Grafton Bridge project, payment for two earlier stages (creating the foundations and constructing the two approach spans) would have allowed the Ferro-Concrete Company to pay off suppliers and workforce.
The opening ceremony was marked by three speeches; first the outgoing Mayor Charles Grey, then previous Mayor Arthur Myers, followed by (big of him) Mr WA Robertson of the Ferro-Concrete Company of Australasia.
Robertson made no mention to the 1909 crisis and bankruptcy of his company. He praised the Council for their vision and commended the City Engineer WA Bush for his role in supervising completion of the project.
Also there were the Governor of New Zealand, Baron Plunket (who had laid the Foundation Stone) and the Prime Minister Joseph Ward, but neither made speeches.
At long last
A link across the Gully had long been needed, since the Auckland Hospital had been established on the east side, in 1848. At that time, the hospital was also deliberately situated to be out beyond the town boundaries, for quarantine reasons.
The bridge carried much traffic to the great Auckland Industrial and Mining Exhibition in the Domain,that ran from December 1913 to April 1 914.
On Monday 5 October 2009 the bridge was re-opened after being closed for reinforcing work.
Strengthening the Grafton Bridge was done as part of the Central Connector Project, a 3 km bus corridor connecting Auckland CBD and Newmarket.
The bridge had a $7 million carbon fibre strengthening upgrade to bring it up to current earthquake standards. It can now accommodate up to 1200 bus daily. The bridge now has a load-carrying capacity of 40 tonnes, up from the previous 13 tonnes.
The work entailed each vertical member of the structure having four holes drilled from top to bottom to receive carbon-fibre reinforcing. This precision work achieved drilling tolerances of 2mm per metre.
Members of the Grey family cut the ribbon at the re-opening ceremony with the original sterling silver scissors used to open the bridge 99 years earlier.
These giant columns supporting the main arch are hollow (but sealed), with staircases up inside them.
This poem by Yang Lian is on the New Zealand Electronic Poetry Centre website.
as you cross the cemetery beneath the bridge closes in
pinetrees raise suspicious faces
an ocean of the dead like iron, giving off a fishy smell
the rusty sunlight has passed by
sniffs at you like an old dog
a dog staring the scene is particularly clear from the bridge
a sky shrivelled by extinct volvanoes a dark red fist
a drop of the past's blood on a low-budget headstone
clouds merge into yesterday's storm
and are fouled by the claws of birds
transparent windows opened by the balustrade you
you cross the bridge at home
an entire city lodged in a sickroom
green weeds linking so many feet together
under a stone roof the roof master closes in
in an iron corridor the iron master closes in
fantasising with the eyes death need not speed up
that end where you go away and turn old
the dead on the lawn looking down at you are all the
same distance away
but you have to come back as though fettered by
handcuffs of glass
to overhaul every pier of today's sins
a child running crazy among snow-white seagulls
standing suddenly stull crying loudly for the stars
with a pain abruptly extended in the night bitterly weeping