Sky Tower

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Information
Sky Tower
Looking up at the Sky Tower / Sky Tower lit up at night.
Location	Auckland City, New Zealand
Status	Complete
Groundbreaking	1994
Constructed	1994-1997
Opening	March 3, 1997
Use	Communications, observation, mixed use
Height
Antenna/Spire	328 m (1,076.1 ft)
Top floor	222 m (728.3 ft)
Companies
Architect	Craig Craig Moller Ltd.
Structural Engineer	Beca Group
Developer	Harrah's Entertainment
Owner	SKYCITY Entertainment Group
Management	SKYCITY Entertainment Group

The Sky Tower is an observation- and telecommunications tower located on the corner of Victoria and Federal Streets in the Auckland CBD, Auckland City, New Zealand. It is 328 metres (1,076 ft) tall, as measured from ground level to the top of the mast,^[1] making it the tallest free-standing structure in the Southern Hemisphere, and the 12th tallest member of the World Federation of Great Towers.^[2] Due to its shape and height, especially when compared to the next tallest buildings, it has become an iconic Auckland structure, often used in logos and promotions.

The landmark is part of the SKYCITY Auckland casino complex, owned and operated by SKYCITY Entertainment Group. However, the complex was originally built for Harrah's Entertainment.^[3]

1 Uses
2 Construction
3 References
4 See also
5 External links

[edit] Uses

Sky Tower in the Auckland skyline.

The upper portion of the tower contains two restaurant levels (one, 'Orbit' with revolving seating, turning 360 degrees once every hour)^[4] and one cafe level, as well as two observation decks (including some with sections of glass floor).^[4] The tower attracts, on average, 1,450 visitors per day (over 500,000 per year).^[5]

The tower also features the SkyJump, a 192-metre^[6] 'fan descender' jump (an experience between a bungy jump and a base jump) from the observation deck, during which a jumper can reach up to 85 km/h (53 mph). The jump is guide-cable-controlled to prevent jumpers from colliding with the tower in case of gusts.^[7] Climbs into the antennae portion (300 m/980 ft heights) are also possible for tour groups.^[6]

As well as for entertainment, the tower is used for telecommunications and broadcasting with the Auckland Peering Exchange (APE) being located on Level 48. Several radio broadcasting companies co-locate transmitters and share antenna systems, while television company Canwest (who runs the TV3 and C4 channels) has secondary transmitters on the tower, their primary one being at Waiatarua.^{[citation needed]}

[edit] Construction

Sky Tower illuminated in Christmas colours. Various other lighting schemes and colours are also used.

Sky Tower as seen from Mt Eden at dusk.

[edit] Project history

Fletcher Construction was the contracted builder for the project while engineering firm Beca Group provided the design management and coordination, structural, geotechnical, civil, mechanical, electrical, plumbing, lighting and fire engineering services. It was designed by Gordon Moller of Craig Craig Moller, and has received a New Zealand Institute of Architects National Award as well as regional awards.^[8]^[9]^[1]

Taking two and a half years of construction time, the tower was opened on March 3, 1997, six months ahead of schedule.^[10]

[edit] Facts and figures

The tower is constructed of reinforced, high-performance concrete. Its 12-metre (39 ft) diameter shaft (containing three lifts and an emergency stairwell) is supported on eight 'legs' based on 16 foundation piles drilled over 12 m (39 ft) deep into the local sandstone.^[9]^[1] The main shaft was built using climbing formwork.^[1]

The upper levels were constructed from composite materials, structural steel, precast concrete and reinforced concrete,^[1] and the observation decks clad in aluminium with blue/green reflective glass. A structural steel framework supports the upper mast structure. During construction 15,000 cubic metres (20,000 cu yd) of concrete, 2,000 metric tons (2,200 short tons) of reinforcing steel and 660 metric tons (730 short tons) of structural steel were used. The mast alone weighs over 170 metric tons (190 short tons).^[1]^[11] It had to be lifted into place using a crane attached to the structure, as it would have been too heavy for a helicopter to lift. To then remove the crane, another crane had to be constructed attached to the upper part of the Sky Tower structure, which dismantled the big crane, and was in turn dismantled into pieces small enough to fit into the elevator.^[1]

[edit] Emergencies

The tower is designed to withstand wind in excess of 200 km/h (120 mph) and resist earthquakes with a 1,000 year return period. Analysis shows that an earthquake centered 40 kilometres (25 mi) away and reaching 7.0 on the Richter magnitude scale is expected to leave the tower practically undamaged. Even an earthquake measured at a magnitude of 8.0 (10 times stronger than a 7.0 quake), and located only 20 km (12 mi) away, is not expected to collapse the tower.^[1] As an additional safeguard against emergencies, fireproof rooms on the lower levels of the observation deck would provide refuge in the unlikely event of a conflagration, while the stairwell itself is also fire-safety rated.^[11]

The sky tower has so far been closed once for weather-related reasons, during a storm in November 2006, when the structure started to sway noticeably in winds of up to 150 km/h (93 mph). The closure was noted as not having been strictly necessary except for visitor comfort, as the tower has been designed to sway up to one metre (39 in)^[12] in high winds of up to 210 km/h (130 mph), which are expected to occur only once in 1,000 years on average.^[1]