On the history highway

Photo © BigStockPhoto.com
Photo © BigStockPhoto.com

How the CN Tower was constructed

For six decades, Construction Canada has been featuring challenging projects and engineering marvels to inspire readers to expand their horizons and find innovative applications for available building materials. The March/April 1973 issue of the Specification Associate carried a lengthy article on a Canadian marvel, the CN Tower, when it was under construction. An excerpt:

The tallest self-supporting structure in the world — an 1807-foot communications and observation tower to be known as CN Tower — is scheduled for completion in Toronto in 1974.

The multi-million dollar Tower will be one of the engineering and architectural wonders of the world.

Construction techniques are unusual. The site will be excavated through 35 ft. of overburden into some 20 ft. of rock and the foundation laid. Special forms will be set up and a concrete shaft will be poured continuously, round-the-clock, using a slipform method. The Tower will rise at the rate of 16 ft. a day.

To maintain non-stop operation, set of forms will be elevated by a ring of “climbing jacks” around the structure. As the forms move up they will leave a continuous extrusion of hardened concrete, reinforced by steel rods.

When [the] concrete reaches the 1500-ft. level large prefabricated supports of steel and concrete will be secured to the main shaft at [the] 1100-ft. level. Twelve supporting steel units will hold the deck on which the Sky Pod will be constructed. Then the 220-ton main antenna will be assembled at the base in sections, raised to the top and fixed in position.

 The CN Tower held the record as the world’s tallest freestanding structure for more than 30 years, until the construction of Burj Khalifa in Dubai, United Arab Emirates, in 2007. Designed and built by Webb Zerafa Menkes Housden (WZMH) Architects, John Andrews Architects International, and a team of engineers and contractors, the tower was completed in 1976.

CN Tower’s significant contributions to Canada’s architectural history and continuing relevance earned it the 2017 Prix du XXe siècle from the Royal Architectural Institute of Canada (RAIC) and National Trust for Canada.

Word processing lessons

Photo © Sailko/Wikimedia Commons
Photo © Sailko/Wikimedia Commons

Laptops, iPads, and smart phones are ubiquitous in this day and age. However, in the 1980s, desktop computers were making an appearance and word processing programs were a novelty and yet another skill for specification writers to master. In the November/December 1987 issue of Construction Canada, Wayne Watson, FCSC, RSW, CCS, addressed computer word processing for the preparation of project specifications.

What types of word processing programs are available? There are only a few good programs available for the Apple MacIntosh. The IBM PC and compatibles enjoy an offering of over 100 word processing programs offering various degrees of flexibility and ease of use.

Word processing software edits text in computer memory, and is either of two configurations. The first it terms “page oriented” and the second is “document oriented”. The “page oriented” word processing packages date back to the 1970s when the cost of computer memory, storage media, and floppy drives [was] expensive. This program type was structured to handle one page of text at a time. Processing of text is slow and awkward. Moving a paragraph of text from one page to another is cumbersome. Repaginating the document (or specification section) is slow.

The “document oriented” programs can load an entire document, or at least a major portion of that document into memory for rapid manipulation of text during the editing process. Why should you be concerned over which type is better? The basic difference is speed of operation. The latter is preferred for specification editing.

The specification writer of tomorrow: A forecast from the past

What did engineers in the 1960s think the role of specification writers would be in today’s construction industry? An article by J. P. Huza, P.Eng., in the June 1963 issue provides a clue. Here is an excerpt.

During his scholastic period, he [the specification writer of tomorrow] will have taken courses in systems and materials applications, and also specialized courses in engineering reports and engineering law… He will be an individual of a well-rounded technical background who could, and will, contribute to all phases of the planning functions, and will specialize in the composition and make-up of specifications. In the office, the specification writer of tomorrow…will contribute greatly to the selection of systems and materials, from the standpoint of both economics and correct applications. In other words, he will be an integral part of the engineering design unit… And, of course, the specification writer of tomorrow will have available standard specification formats produced by the Specification Writers Association of Canada which will be of immeasurable assistance to him.

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