Television, a technological wonder of the 20th century spurred the building of the era’s tallest freestanding structure. The signals from conventional transmission towers started getting problem because the skyscrapers in Toronto were creating disorders in transmission signals. The signals bounce off the city’s skyscrapers and create a lot of problem in television sets. Stronger and weaker signals were competing each other and in result viewers were getting two programs at once. To tackle this problem, Canadian National Railways or CN suggested building a transmission tower that would stand taller than all standing buildings in Toronto.
Description
CN Tower’s initial design was prepared by a Toronto firm along the enlisting of engineering experts world over. The initial or original plan was showing three towers linked by structural bridges but gradually the design was developed into a single 1,815.5-foot-tall tower comprised of three hollow legs.
Its foundation work was started in 1973. The giant backhoes dig out more than 62,000 tons of soil and almost 50 feet deep in earth along the shore of Lake Ontario in Toronto harbor. After that stretched wires and 22 feet thick reinforced concrete was put in Y – shaped order strengthened it. Every hollow leg of the Y is having capacity of carrying burden of 130,000 ton.
The foundation work was completed only in 4 months. But the height of the tower was a challenge because it was impossible to build it up with the technique of poured concrete. For this problem the engineers designed a huge mold known as a slip form. Concrete was poured in the molds 24 hours a day, five days a week and when it get hardened the molds were moved upward with the help of a ring of a hydraulic jacks. The ascending slip form gradually decreased in girth to give the tower its tapering shape.
SkyPod
SkyPod a seven-story structure consists of two observation decks, a revolving restaurant, a nightclub, and broadcasting equipment.
When the tower was constructed till the height of 1,100-foot mark then preparations were made to build SkyPod. 12 steel and wooden brackets were pushed up to the tower by 45 hydraulic jacks for stabilizing the SkyPod. SkyPod is having concrete walls and a doughnut shaped ring, called a radome that was added to its base to protect the delicate microwave dishes receiving radio and television transmissions. To access the SkyPod on the tower there are 4 high-speed glass fronted elevators.
The concrete tower ends up at the Space Deck 1,465 feet up. The Space Deck is having support of cantilevers that stretch out of the concrete section beneath it. A 58 second elevator ride from the SkyPod below, visitors can take a breathtaking view from a glass-enclosed balcony. On a clear sunny day 75 miles a way sites can be seen also.
In the last phase of construction a Sikorsky Skycrane helicopter were used to install the tower’s 335-foot communications mast.
The helicopter lifted up one by one 47-ton sections of the mast to the top of the tower where workers received them. At the top those sections were secured by a total of 40,000 bolts. After that whole mast was covered with a fiberglass-reinforced sheathing to prevent icing.
The CN Tower was completed in 1975 with the cost of $57 million.
The CN Tower’s wind tolerance standard is 260 miles an hour, which is well above nature’s most extreme demands. The antenna is having counterbalancing weights that makes it to not wobble in high winds. To protect it from lightening copper grounding wires were installed.
In new developments on the CN Tower are that two new elevators are gained to accommodate an increase in visitors. A glass floor is added on the SkyPod’s observation deck.
In height CN Tower is twice taller than Eiffel Tower and thrice than the height of the Washington Monument. The CN Tower is proud of the Toronto and most of all it expelled all ghost from the TV sets of Torontonians.
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