Canada’s Engineering Marvel Celebrated

Toronto’s CN Tower celebrated a quarter-century on June 26. The tower took 40 months to erect and was opened to the public 25 years ago on June 26, 1976. It is still the world’s tallest building and free-standing structure, standing at a height of 553.33 metres or 1,815 feet. In 1995 it was classed as one of the Seven Wonders of the Modern World by the American Society of Civil Engineers.
Unfortunately, in all the hoopla that attended the celebrations last week, there was no mention of the engineers who helped to raise the landmark — arguably Canada’s most distinctive monument. Nicolet Carrier Dressel & Associates of Montreal were listed as the civil engineers when it won a Canadian Consulting Engineering Award of Excellence in 1977.
The tower cost $63 million to build, or about $300 million in 1998 dollars. In recent years, $40 million has been invested in expanding its underground facilities and on renovating its revolving restaurant in the pod.
Building the slender tower took 40,500 cubic metres of concrete, 128 kilometres of post-tensioned steel, 4,500 metric tonnes of reinforcing steel, and 540 metric tonnes of structural steel. The tower is used to transmit UHF and VHF television, FM Radio, microwave transmissions and fixed mobile systems. During high winds (120 mph with 200 mph gusts) the shaft will sway 1 foot 7 inches from the centre, the antenna moves over 6 feet from centre, and the sky pod moves over 3 feet from centre. Wind studies were done at the Boundary layer Wind Tunnel Laboratory of the University of Western Ontario in London when it was designed.
Glass-fronted elevators climb the tower at 22 kph to take 58 seconds to reach the pod. The pod platform has a solid glass floor that could withstand the weight of 14 large hippos.

List of World Federation of Great Towers
1. CN Tour, Toronto, Canada, 553 metres
2. Ostankino Tower, Moscow, Russia, 540 metres
3. Empire State Building, New York, U.S.A., 443 metres
4. Tianjin Tower, Tianjin, China, 415 metres
5. Tashkent Tower, Uzbekistan, 375 metres
6. Fernsehturm, Berlin, Germany, 365 metres
7. Tokyo Tower, Japan, 333 metres
8. Sydney Tower, Australia, 304 metres
9. Olympia Tower, Munich, Germany, 290 metres
10. Barcelona Tower, Spain, 288 metres