NOVEMBER 27, 1975
The CN Tower
AN ADDRESS BY Malachy Grant,
DIRECTOR OF DESIGN AND CONSTRUCTION, CN TOWER
CHAIRMAN The President,
H. Allan Leal, Q.C.
Mr. Grant, ladies and gentlemen: We bid you welcome to this meeting of The Empire Club of Canada.
We are holding this luncheon meeting in the Imperial Room not through choice but because this was the only accommodation available to us, the Royal York having committed all other space to their convention clientele. Your executive held the view that it would be preferable to accept this accommodation rather than to cancel the meeting or to go elsewhere. We hope that you will bear with us. May I say, as well, that we all have terms of reference within which we must operate, and one of these for the management of the Royal York is that they are requested to show a profit on their operations. We have reason to be grateful for their splendid assistance and co-operation on other occasions.
Our distinguished guest today is Malachy Grant, Director of Design and Construction of CN Tower Limited. I hope he will forgive me, but I am intrigued with his given name and this has driven me in my researches to the New Westminster Dictionary of the Bible. There I find the doubt expressed whether Malachi was really the proper name of the Old Testament prophet or whether it was descriptive of one of the other prophets. The name Malachi meant in Hebrew "my messenger or messenger of Yahweh".
In any event, it is a fact that the biblical Malachi wrote the last book in the Old Testament. Mr. Grant is here today to give us a description of the last word on free standing structures and for that purpose he is the messenger of CN Tower Limited.
He is an Irishman, having been born in Newry, County Down, and educated at St. Mary's College, Dundalk and the Bolton Institute of Technology in Dublin.
Before coming to Toronto, he ran his own consulting company in Montreal, specializing in project construction and management. In those lines of endeavour he was involved in the planning and construction of Habitat, the La Ronde amusement area and many other major elements in Expo '67, by which this country and its technicians gained a justifiable international reputation for excellence.
In Toronto, he served as Manager of Design and Construction for Metro Centre Developments Limited from 1969-72 before applying his energies and talents to similar tasks on the CN Tower.
Whether as a mammoth harbour light guiding the homeward steps of her native sons, or as an intricate and advanced communications link bringing the world community to our doorstep, it stands now and for generations to come as a symbol at the very heart of a vital and throbbing major world community.
We welcome Mr. Grant here today to tell us more about it and I am happy to invite him to address you.
Mr. Chairman, ladies and gentlemen: first, may I thank you for giving me the opportunity to address you. My subject, the CN Tower, makes it a very pleasant task.
Over six years of effort have gone into the exercise of producing what you see today as the most prominent feature on the northern shore of Lake Ontario.
Since time is limited in this luncheon and even a limited presentation on the CN Tower would likely take more than one hour, perhaps you will bear with me if I limit myself to certain aspects of the project. I feel sure that some people here have probably already attended a presentation on the CN Tower, or heard or read about it in fair detail in the news media. I will try to be brief on the items covered most adequately by the news media, and perhaps give you an insight into the people and events which made it all possible.
In 1968, I was approached by "Bud" Andrews, the then President of the Metro Centre Developments Group, to head up a design and construction team to convert an artist's concept into the reality of the present structure.
It would be remiss if I did not make mention here of some of the early participants involved. Howard Hilliard of the CBC was one of the originators of the tower idea. I believe that it takes men of courage and foresight to advocate and finally make the big decision to proceed with what could have been a controversial project. The executive of CN, Mr. Norman MacMillan, the past Chairman, and Dr. Robert Bandeen, the President, were responsible for the decision which permitted us to proceed.
As one can imagine, the design team of the CN Tower encompasses a very wide range of disciplines and a large number of consultants. They range through architects, structural, mechanical and electrical engineers, psychologists, soil investigation engineers, ornothologists, vibration engineers, lightning consultants, hoisting consultants, material testing consultants and so on. The principal consultants were: Webb, Zerafa, Menkes, Housden, and John Andrews, Architects; Roger Nicolet & Associates, Structural Engineers; Ellard-Willson & Associates, Mechanical and Electrical Consultants; Cordon Elder, Transmission Consultant. We also had as a consultant a very prominent member of the Empire Club, Bud Hoffman, because of his experience in the construction and operations in the Skylon Tower. He advised us on crowd control and operations.
The principle and active members of the design and construction team are seated here in front of the head table: Ned (Edward) Baldwin, Architect; Roger Nicolet, Structural Engineer; Franz Knoll, Structural Dbsigner; Frank Tam, Structural Site Engineer; Jules Petrinec, Mechanical Engineer; Jim Armstrong, Electrical Engineer; Andre Jordan and Jack Whyte of Foundation Company of Canada, who were responsible for the construction. Together with these men we worked not in the luxury of a downtown office building, but in the mud and dust of the construction site, where we figured out the detail and solved the problems to accomplish the feat of making the CN Tower a reality.
Visits to other towers dictated that there were certain aspects to which we should pay particular attention in the CN Tower.
The juncture of the massive structure to the ground line would be a design problem. We incorporated a reflecting pool which gracefully solved the problem. We wanted to avoid a clutter of buildings at the base of the tower. All service entrances to the tower are underground and service buildings, loading docks, and so on are located at a distance.
Most towers provide an elevator ride, a view, and a ride back down again. We resolved to make the tower visit an exciting and memorable one, so that the public would not feel they were being ripped off. We have built in many attractions and added features for the entertainment of the visitors.
As you are probably aware, the budget which was originally just under $30 million has now increased to over $50 million. A good part of that increase was the result of increased facilities, such as an extra floor in the sky pod level and the observation deck known as the "Space Deck" at the 1500 foot level, and the doubling of the facilities around the base of the tower. Also, an appreciable amount of money had to be spent on bridges and roads because of the shelving of the Metro Centre Project. Of course, inflation didn't help.
On the other hand, the CN Tower has carried out a truly remarkable marketing program under CN Tower General Manager, Eldon Dolphin, and the projected income has maximised to a degree I did not believe possible two years ago.
My mandate, as defined by CN, was that the tower should be structurally sound, functional, economical and esthetically pleasing with sculptural qualities. I think we have succeeded on all counts, as you will see in the slide presentation which follows.
The original concept of the tower was a three tube structure, connected with concrete bridges every 150 feet in height.
This exciting design had a restaurant designed like a Saturn Ring which was attached to the structure in only three locations. It had the unique feature of being able to view both inside and outside at the restaurant level.
We spent the best part of a year on this design before coming to the conclusion that it was nearly impossible to construct, very difficult to design structurally and the cost would be astronomical. An evaluation of this original three tubed structure resulted in the present graceful profile.
The majority of visitors will arrive at the tower from the north side. A large 700 car parking lot is located just south of the entrance on Front Street.
An attractive, glass-enclosed pedestrian bridge affords access across the present railway tracks into the main lobby of the tower.
Tour buses, taxis and paraplegics arriving at the tower will come from the south, through the extension of John Street, to arrive at a well-appointed plaza just west of the tower entrance.
There is a fast food outlet and a commercial area which occupy a portion of the Entrance Building. In the main lobby, a large multi-screen display will show all of the TV programmes being transmitted by the tower facility and also all those which the tower is capable of receiving. Another glass-enclosed bridge gives access from the Entrance Building, across the reflecting pool to the central lobby area which contains the main tower elevators.
Extensive research and expert psychological advice has resulted in the design of elevators that give a very secure and safe feeling, even to the most nervous passenger.
The ride in the elevators should prove to be a very exciting experience. The elevator shaft is enclosed on its front face by a wide fourteen foot glass window. The front of the elevator cab, the side of the cab and portions of the roof are also transparent. This enables one to look up the elevator shaft to see the other elevator descending towards you.
The elevators will discharge onto a floor of the sky pod which is known as Main Observation Level. In this area we have designed a number of attractions.
One of these is an array of six telescopes. The telescopes are a much superior instrument to any viewing telescope installed in other towers anywhere in the world. We undertook a very elaborate research and development program in order to produce the telescopes. The zoom will produce a 200:1 magnification. If the telescopes were used at night, about half of the moon's surface would fill the telescope viewer.
On the Main Observation Level, we also have incorporated two audio-visual ,mini-theatres which should prove to be an exciting attraction.
From the Main Observation Level, one can take an elevator to the uppermost observation level, known as the "Space Deck". This top viewing level, which is the highest observation deck in the world, gives an absolutely different appreciation of the view than one gets at the sky pod level.
One appreciates the beauty of Metro Toronto from this high vantage point: the beautiful harbour, lakefront and beaches, and Lake Ontario; the constant activity of automobile traffic, the Island Airport, boating on the lake, air traffic to Malton Airport. The panorama is always active and exciting.
Having examined many of the towers around the world, the design team came to the conclusion that the restaurant patron should be handled separately and this is one of the reasons that the dining floor is the uppermost of the three public floors.
The food facilities will be operated by CN Hotels. They have perfected a highly sophisticated computer-controlled system of handling restaurant patrons, establishing table readiness status and the booking of tables. I am convinced the restaurant design will win many awards and will prove to be a most inviting and comfortable experience.
From the 1500 foot level, the steel antenna mast structure extends to over 1800 feet. The steel mast serves as a support for the antenna elements and the feedlines serving, in the future, up to fourteen FM stations and eight TV stations. This total steel structure, complete with the antenna elements and feedlines, is enclosed by a heavy fibre-glass cylinder of various diameters. This is to prevent ice accretion on the antenna elements and the creation of a hazard to downtown Toronto by heavy pieces of falling ice.
With regard to the construction phase of the tower, here are some items of interest which I will cover very briefly.
To form the concrete 1500 foot shaft of the tower, we used what is known as a slipform method. This consists basically of forming a very large mould, jacking it skyward and filling it with steel and concrete and extruding the concrete shape of the tower out of the bottom of the mould. This type of operation had never been attempted before in an area as big as the tower.
It was very complicated as you can imagine with over 30,000 items to be built into the concrete walls. The tower shape centres around a 34 foot hexagon with 90 foot projections or legs and it was difficult to hold them in line, but we succeeded in finishing the tower and the whole structure is within one inch of being absolutely plumb and in a proper alignment from the top of foundation to the top of concrete.
Of the 100,000 tons of concrete used in the tower shaft, not one bad mix of concrete was actually deposited in the forms. No man was killed or injured seriously as a result of the height of the tower.
We inserted 144 groups of heavy cable, each of these groups, which extend in varying heights from 300 feet up to 1500 feet, have had exerted on each of them a tension of up to 350 tons. This helps to give the tower structure the degree of rigidity demanded by the broadcast elements. In a very high wind, say 100 mph, the top of the concrete shaft is likely to move out of the perpendicular only about 18 to 20 inches.
You should not think of the tower as swaying like a pendulum. It merely deflects out of the perpendicular in one direction. The active portion of that 18 inch arc is probably about from 12 inches to 17 inches, so that the movement even in a very high wind is hard to detect in the concrete shaft. Recent tests have shown that the tower performance even surpasses design expectations under wind-loaded conditions.
The tower rests on a foundation which in turn rests on rock. In order to determine the rock's bearing capacity to ensure the integrity of the rock at depths well below the foundation, we drilled test holes, up to 300 feet. In our final phase of soil investigation, we drilled holes 30 inches in diameter 130 feet deep in the rock, and soil investigation engineers from the University of Toronto, Drs. Eli Robinsky and John Morton, actually went into these deep holes and examined, took samples of and photographed the various layers of rock to ensure a positive foundation condition.
Models of the tower had been subjected to testing in wind tunnel facilities at the University of Western Ontario to determine structural requirements and we also learned of one or two unexpected features. It is interesting that the model was required to match the tower in scale not only in height, width and other dimensions but it also was constructed to match the strength and other characteristics of the concrete and steel to be used in the actual construction.
Like every high-rise building the tower is occasionally struck by lightning. The tower lightning arrestor system has been called into operation many times and lightning has absolutely no effect.
Without reservations, I say that the CN Tower is the safest, best constructed, best designed, most efficient broadcasting facility, and probably, as I have already mentioned, the most rigid structure in the world.
Since the tower project did not have any predecessors upon which we could base our design approach, and since the construction methods to be used in the erection were very unusual, there were many difficult areas. Each operation was new and presented unique problems, and we had to invent and innovate from the start.
The antenna mast structure, after very deep analysis, was erected using a helicopter. The mast and the joint plates connecting the separate sections were lifted by the helicopter. The two ring elements are actually each ten ton pendulum-like weights used to dampen the tendency of the mast to deflect under high wind-load conditions.
Few people realize that we investigated the possibility of using a giant balloon to fix the antenna mast. Our engineers went to the west coast to watch large balloons bring twenty ton logs down the mountain sides in Oregon. We developed a method to use a balloon, but finally came to the conclusion that balloon technology was not sufficiently advanced and our chances of success were better with a helicopter. In the event that the helicopter solution proved, in practice, to be non-workable, we fabricated the antenna mast in such a fashion that if we were forced to we could have reverted to a regular piece by piece installation. It would have cost a great deal more in time and money, but I point this out to indicate to you that while we were innovative we could not afford to be boxed into a corner from which we could not find an alternate solution.
We had many anxious moments during the construction of the tower. One of them was when the cable hoisting system, which we used to bring up the brackets which support the sky pod at 1200 feet, failed when we first tried it. This operation required a 350 ton load, in six separate sections, to be hoisted 1200 feet in the air, simultaneously. The system failed on a trial run, and two tons of wire rope came tumbling down around the base of the tower. It took us a month to recover from this reversal and again it was the ingenuity of the engineering brains associated with the tower which came up with a solution. We tested it and finally used it successfully.
I suppose the most anxious moment, for me personally, was the very first lift of the helicopter operation. We had been over the details of this first lift many times, in which we were to pick off the very long, eighty foot front boom of the crane.
The helicopter only carried about fifty minutes of fuel, because of the fact that the operation was expected to take ten minutes. This was the first introduction of the helicopter to the tower project and it seemed that all Toronto watched the helicopter position itself above the front boom of the crane. It lowered the harness and the harness in turn was attached to the boom. It was planned that the iron workers would, on two sides of the boom, extract the pins which were then holding it together and let go the crane boom so that the helicopter could lower it to the ground.
Many aspects of the helicopter operation were to be determined that day: the effect of wind, the effect of the tower on the surrounding air currents, the up lift from the tower itself. However, when the ironworkers extracted the pins from the south side of the boom, it was found that the harness attaching the boom to the helicopter had not been exactly balanced and when the pins were extracted from the south side, the boom lurched and twisted. When the pins on the north side of the boom were to be extracted it was found that they were twisted and jammed. They could not be taken out in the usual fashion. Torches were brought into position and the slow process of burning out the pins took place.
The public generally were not aware of this fact, but as the minutes ticked by the helicopter was still hovering over the boom. After half an hour I could foresee the necessity, because of the lack of fuel, of the helicopter having to dump the load, the balance of the helicopter operations being cancelled and the whole project being held up for about six months while the antenna was erected in a conventional manner.
What happened, in fact, is history now. The iron workers successfully burned out the twisted pins, the boom swung loose, and the helicopter very slowly and gracefully lowered the boom to the ground.
All of the operations of a difficult nature were carried out successfully and efficiently on the tower project. There were many other instances of concern, frustration, and irritation, but these were far out-weighed by other occasions of satisfaction and of success.
There are many stories concerning the early design days and the final design and construction period which have yet to be told. There are other designers, the workmen on the jobsite, and some women all deeply involved in the project whom I have not mentioned. But, for now, I hope I have taken you a little closer and made you a little more aware of that extraordinary and unique project of which we all own a share, the CN Tower.
Our distinguished visitor and speaker was thanked by Mr. Charles C. Hoffman, a Director of The Empire Club of Canada.