Sky Tower Turns 25 Today

Published: Wed 3 Aug 2022 09:33 AM
Auckland’s iconic landmark the Sky Tower is celebrating its 25th birthday today (August 3). The Tower has gone from controversial beginnings – many objecting to a tower of its size dominating the Auckland skyline – to become a much-loved symbol and feature of the City.
More than 10 million people have visited the Tower since it was built by Fletcher Construction in 1997. At 328 metres it’s the tallest structure in the Southern Hemisphere.
SkyCity’s CEO, Michael Ahearne, says the Tower is one of the most visited tourist attractions in the country: “SkyCity owns the Tower, but really we’re just the custodians of it – it really belongs to the people of Auckland.”
A renowned feature of the Tower is its ability to light up in different colours for charities such as Pink Ribbon Day, community initiatives, national holidays, milestones or other celebrations or events.
Sky Tower has been designed and built with safety in mind and is designed to cope with the elements of nature.
The larger diameter base gives full resistance to seismic and wind forces. The Tower can withstand storms with winds gusting to 200kph/hour (125mph) – an occurrence which is predicted to happen only once in 1,000 years – and is capable of safely swaying one metre at the top.
Sky Tower is built to withstand an earthquake of a magnitude of 7.0 at 40 kilometres, or a magnitude 8.5 at 360 kilometres.
In the unlikely event of fire, Sky Tower is equipped with a fire hydrant system that pumps 2,400 litres of water a minute. The upper section of the tower contains a 3-floor refuge able to accommodate over 800 people.
In case of lightning strikes, a gold-plated spiked metal dynosphere, 50cm in diameter, is positioned at the top of tower’s 90 metre steel mast. This is designed to attract lightning, direct it down the cable and into the foundations where energy is dispersed into the earth.
Sky Tower has 65 levels, and a total of 1,267 stairs leading from the base to Sky Deck, the highest public observation level. The elevators will take you to:
• Sky Lounge (182 metres) where you can relax with a coffee in the highest café in New Zealand
• The Main Observation level (186 metres), the Sky Tower’s main viewing platform. Stroll over 38mm glass floors, check the up-to-date live weather feeds, find out about Auckland with live-camera touch screen computers, or simply sit and take in the spectacular view
• Sky Deck (220 metres) is the highest public observation level in the Southern Hemisphere and offers amazing views through virtually seamless glass
· At 328 metres (1,076 feet) above street level, Sky Tower is the tallest structure in the Southern Hemisphere
· It is the twelfth highest tower in the world, topping the Eiffel Tower in Paris by 8 metres and Sydney’s AMP Tower by 24 metres
· Construction took 2 year 9 months, with the Sky Tower opening to the public on 3 August 1997
· Sky Tower cost approximately $85 million to build and is owned by SkyCity Entertainment Group Limited, an NZX listed company.
· Materials used in construction include:15,000 cubic metres of concrete2,000 tonnes of reinforcing steel660 tonnes of structural steel260 panes of glass
· The Sky Tower is as tall as 37 buses laid end to end.
· The amount of concrete used to build Sky Tower could fill your gumboots 8,765,903 times.
· The empty building weighs 21 million kilos, which is equivalent to 6,000 elephants.
· The crane was struck twice by lightning during final construction. On both occasions the driver was pre-warned by a special weather station and computer in his cab and he safely evacuated in plenty of time.
· During construction of Sky Tower and the SkyCity complex, workers consumed 545,000 meat pies and drank 1,245,000 cups of tea.
· During a thunderstorm in July 1999, lightning hit Sky Tower 16 times in 30 minutes, providing a spectacular sight for many Aucklanders and resulting in television news coverage and front page of The New Zealand Herald. The lightning conductor on the mast ensured that there was no damage to Sky Tower.
· AJ Hackett completed a record-breaking bungy jump off Sky Tower on 5 October 1998, from the Outdoor Observation level.
· The glass-fronted public lifts travel at approximately 18 kilometres per hour (5 metres per second) with each ride taking around 40 seconds.
· The glass floors in the lifts are 38mm thick – they may be scary to walk on, but they are stronger than the concrete that surrounds them!CONSTRUCTION
Sky Tower comprises a hollow reinforced concrete shaft, 236 metres tall and 12 metres in diameter, which is supported on a concrete foundation pad. At the base, eight reinforced concrete legs, each 2m in diameter, help to spread the force load.
To ensure a perfectly safe “shift-proof” foundation, Sky Tower is constructed from a high strength, high performance concrete and its foundations go down more than 15 metres into the ground.Preparation
The demolition of old buildings and excavation on the 1.26 hectare site was the largest ever for a commercial project in New Zealand.
The construction site, measuring just 1,400 square metres, is not much larger than a standard residential plot, so extreme care had to be taken around the neighbouring properties.
Vertical precision was crucial in the Tower’s construction. Constant verification using the most sophisticated telemetry ever employed in New Zealand ensured the Sky Tower is perfectly straight.
During construction of the shaft, lasers on the base pad shining upwards in a grid pattern provided verticality readings. The tower’s exact position was verified by daily real-time readings from seven global positioning satellites.Building
The Sky Tower was built using a technique specially developed by Fletcher Construction from researching tower-building processes around the world and is believed to be a world first. A unique crane incorporating an automatic climbing technique enabled it to climb up the inside of Sky Tower and hoist building materials up where required.
But once you have a crane up a tower, how do you get it down? Here, another special procedure was developed. The 65 tonne crane was dismantled using a small derrick secured to the permanent mast of Sky Tower. The crane lowered itself hydraulically, below the derrick and was then dismantled bit by bit and each section was lowered to the concrete floor which forms the roof of level 52.

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