| |
Concrete
Contractor Home > Historic
Concrete Projects > The CN Tower - Toronto, Canada
 The
CN Tower - Toronto, Canada
The World's Tallest Building, 1976
In the early 1970s the city of Toronto's building boom created
an interesting problem. Because the transmission towers of
the city's TV stations weren't tall enough, many people weren't
receiving high quality television reception. Canadian National
decided to solve that problem and in 1972 conceived of a tower
that would not only allow for uninterrupted broadcast signals,
but would also be the tallest building in the world.
The engineers had a huge challenge. They had to design a
tower with a base that was far underground. They tested the
soil to see how it would react to changes in hydrostatic pressure
and on February 6, 1973, they set to work. Before contractors
could pour the concrete and steel foundation, 62,000 tons
of earth had to first be removed. The base of shale was then
smoothed by both hand and machine and a foundation 22 feet
deep, containing 9,200 cubic yards of concrete, was poured.
In spite of the massive scope for this groundwork, it took
only four months from start to finish to complete the foundation.
Next came the building itself. In August of 1974, workers
began using steel and wood brackets that had to be lifted
up the sides of the tower by hydraulic jacks in order to complete
the building. The tower was topped by an observation deck,
constructed of brackets bolted to tensioned steel bars, concrete
and a three feet high compression ring. All in all, it took
40 months for the 1,537 construction crew members working
24 hours a day for five days a week to complete the CN Tower.
 Over
that time concrete contractors poured 53,000 cubic yards of
concrete, accounting for much of the building's 130,000 ton
weight. The total cost for this project was $63 million, which
would be about $300 million today.
The building stands more than 1,815 feet tall - that's over
six football fields standing end to end - and is visited by
about two million people every year. Located at 1,122 feet
is the outdoor observation deck, at 1,136 feet is a café
and indoor observation deck, and if you go just a bit higher
to 1,150 feet, you'll find an award-winning rotating restaurant.
At the very top is the Sky Pod, the world's highest public
observation deck.
The CN Tower has been recognized as the world's tallest building
by the Guinness Book of World Records and includes the world's
highest wine cellar and longest metal staircase. The tower
was named one of the Seven Wonders of the Modern World by
the American Society of Civil Engineers in 1995.
|
