CN Tower

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In the previous post of architectural segment, we have cover about the Taipei 101. Today, we are going to see the tallest free-standing structure on land in the world, The Canada’s National Tower, or commonly used as CN Tower. Even though have a height of 553.33 meter, it is not considered the highest building in the world.

The CN Tower, located in downtown Toronto, Ontario, Canada, is a communications and observation tower. On September 12, 2007, after holding the record for 31 years, the CN Tower was surpassed in height by the still-under-construction Burj Dubai. It remains the tallest free-standing structure in the Americas, the signature icon of Toronto's skyline, and a symbol of Canada. The architect of the tower is John Andrews Architects in association with WZMH Architects.

In 1995, the CN Tower was declared one of the modern Seven Wonders of the World by the American Society of Civil Engineers. It also belongs to the World Federation of Great Towers.


CHARACTERISTICS

The CN Tower consists of several substructures. The main portion of the tower is a hollow concrete hexagonal pillar containing the six elevators, stairwells, and power and plumbing connections. On top of this is a 102-metre (334.6 ft) tall metal broadcast antenna, carrying TV and radio signals. There are two visitor areas: the main deck level (formerly known as SkyPod) located at 346 metres (1,135 ft) and the higher Sky Pod (formerly known as “Space Deck” at 446.5 metres (1,465 ft), just below the metal antenna. The hexagonal shape can be seen between the two areas; however, below the main deck, three large supporting legs give the tower the appearance of a large tripod.

The main level is seven stories, some of which are open to the public. Below the public areas — at 338 metres (1,108.9 ft) — is a large white donut-shaped radome containing the structure's microwave receivers. The glass floor and outdoor observation deck are at 342 metres (1,122.0 ft). The glass floor has an area of 24 square metres (258 sq ft) and can withstand a pressure of 4,100 kilopascals (595 psi). The floor's thermal glass units are 64 millimetres (2.5 in) thick, consisting of a pane of 25-millimetre (1.0 in) laminated glass, 25 millimetres (1.0 in) airspace and a pane of 13-millimetre (0.5 in) laminated glass. Some people experience acrophobia when standing on the glass floor and looking down at the ground 342 metres (1,122.0 ft) below. In 2008, one elevator was upgraded to add a glass floor panel, believed to have the highest vertical rise of any elevator equipped with this feature. The Horizons Cafe and the lookout level are at 346 metres (1,135.2 ft). The 360 Restaurant, a revolving restaurant that completes a full rotation once every 72 minutes, is at 351 metres (1,151.6 ft). When the tower first opened, it also featured a disco named Sparkles, billed as the highest disco and dance floor in the world.

The Sky Pod is the second-highest public observation deck in the world, surpassed only by the Shanghai World Financial Center. On a clear day, it is possible to see 100 to 120 kilometres (62–75 mi) away, to the city of Rochester across Lake Ontario in the United States, the mist rising from Niagara Falls, or the shores of Lake Simcoe.

A metal staircase reaches the main deck level after 1,776 steps, and the Sky Pod 100 metres above after 2,579 steps; it is the tallest metal staircase on Earth. These stairs are intended for emergency use only and are not open to the public, except for three times per year for charity stair-climb events. The average climber takes approximately 30 minutes to climb to the base of the radome, but the fastest climb on record is 7 minutes and 52 seconds in 1989 by Brendan Keenoy, an Ontario Provincial Police Officer. In 2002, Canadian Olympian and Paralympic champion Jeff Adams climbed the stairs of the tower in a specially designed wheelchair.


PURPOSE

The CN Tower has been and continues to be used as a communications tower for a number of different media, and by numerous companies.

Among the television broadcaster are CBC, CTV, TVOntario, and Citytv.

Among the radio broadcasting at CN tower are JAZZ.FM91, Kiss 92.5, and 102.1 the Edge. All operated in FM and no AM broadcasting from the tower.

Motorola also operated in broadcast from this tower.


SAFETY FEATURES


Among of the safety measures that been implemented at the tower.

1. the fireproof building materials used in the tower's construction
2. frequent and stringent safety inspections
3. an extensive sprinkler system
4. a 24-hour emergency monitoring operation
5. two 15,000-imperial gallon water reservoirs at the top, which are automatically replenished
6. a fire hose at the base of the structure capable of sending 600 imperial gallons a minute to any location in the tower

Officials also noted that the CN Tower has an excellent safety record and that there has never been an accidental fire in the tower since it was opened in 1976.

COMMENT

Up until now, I'm still confused what the characteristics of a structure are so that it can be considered as building. As you can see in the figures below, it is clearly shown that the tower can claimed the title of the world highest building.

Whatever the reason, it is still among the most spectacular tower I ever see..