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.
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