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70's-era CN Tower photos wanted: inside construction, antenna signing, opening day...

whatever

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First of all, I would like to thank everyone who provided their input on my CN Tower heritage project. That input lead to an expanded network of key personnel who had worked on the tower, and who are still alive. I have not come across any people who took pictures of the antenna signing yet, but I know such pictures must abound.

There's a few neat pictures from the tower's construction up on the walls of the Ironworkers hall (909 Kipling, call ahead), and I bet they have lots more pictures kicking around. Wouldn't surprise me at all if someone had pictures from the signing in a filing cabinet.
 

lansd

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I was always intrigued by the dark lines on the side of the tower from the forms

Having watched two 1975-era movies at the Toronto archives yesterday, and talking with Canron's field engineer, the raw concrete was covered with a "parging" of thin cement troweled on by workers. The make-up of each batch of concrete varied from day to day, leading to the banding you can see on the tower. He also mentioned that the banding should be less obvious on the south side of the tower due to the uv-ray bleaching of the sun. The crappy looking patches seen on the tower today are due to the parging falling off and being replaced.
 

lansd

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There's a few neat pictures from the tower's construction up on the walls of the Ironworkers hall (909 Kipling, call ahead)

I called them up in May 2012 but there wasn't much interest at that time. In the interim I've found the names of a lot of ironworkers and called them up directly and/or interviewed them. My photo collection and information is growing rapidly from them. Everyone has a good story to tell! I know of those large poster shots.
 

lansd

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Pulling up the tracks, east yard - Dec 8 1972.jpg


CN Tower - Start of construction. Pulling up the tracks, east yard - Dec 8 1972

December 8th 2012 marks the exact 40th anniversary of the CN Tower's physical start of construction. This photo, by way of George Rumble, shows Rumble Contracting removing the railroad tracks in front of the "shed". Teperman would also be removing half of this shed at the same time, with the other half being used by Foundation Co. (the main contractor) until 1976.

This image marks the first of 4 years of important moments in time that defined the CN Tower's construction timeline. Others will follow as each important event achieves its 40th anniversary.

The Metro Centre concept was unveiled to the public on December 19th 1968. The CN Tower's design and pre-planning took place from 1969 through to late 1971. Construction personnel were hired on during 1971 and into early 1972.

(As copied from my Flickr account)
 

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lansd

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February 6th 2013 marks the 40th anniversary of the start of the CN Tower's excavation work by George Rumble of Rumble Contracting. Excavation work proceeded quickly over a period of 6 weeks but got delayed a bit due to the warm winter temperatures and soft soil. Total contract value was $3mil in 2013 dollars. 65000 cubic yards of overburden and 15000 cubic yards of bedrock were removed using three Caterpillar D-8 dozers, three Caterpillar 463 scrapers pulled by three other Caterpillar D-8 dozers, two Caterpillar 621 scapers and a Terex TS18 scaper to excavate 'clayey' subsoil to the 18ft level. The remaining 12ft of overburden was removed by three Poclain 200 backhoes and a Liebherr 971 backhoe.

The next interesting anniversary dates will correspond with April 1973 (foundation development), May 1973 (building of the slip form) and June 26th 1973 (the first pour and jacking of the concrete slip form).

The Metro Centre concept was unveiled to the public on December 19th 1968. The CN Tower's design and pre-planning took place from 1969 through to late 1971. Construction personnel were hired on during 1971 and into early 1972. The project engineers (Foundation Company) came to the site in November 1972 and then the railroad tracks were cleared by Rumble Contracting on Dec 8th to 11th 1972.

Rumble Excavating the CN Tower Foundation - Feb and March 1973.jpg
 

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lansd

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March to May 2013 marks the 40th anniversary of the completion of the CN Tower’s foundation excavation and the laying of the foundation mat of concrete & rebar. The images show the early phase of the foundation mat being built. Once the rock was excavated, a thin layer of quick-set concrete was sprayed onto the rocks to keep them from drying out. Then a lattice of rebar was cris-crossed to form the lower, then upper, portions of the hollow foundation structure. While many people believe the foundation “must be hundreds of feet deep”, in actual fact it is a mere 18 feet high with a “toe” on the outside edges to prevent rock fracturing. The low centre of gravity of the tower keeps it upright even in the worst of windy conditions.
Foundation Construction - April 1973.jpg
 

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lansd

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May and June 2013 marks the 40th anniversary of the creation of the CN Tower’s “slipform†structure. The slipform was designed, engineered and put into operation by Doug Sumner, P.Eng between January and June 1973. The slipform is basically one massive and heavy “mold†into which workers placed rebar and concrete, after which the concrete set, the entire structure would be jacked up another inch every 5 to 10 minutes. This continued until the 1464ft level on Feb 22 1974.

In the upper left image you can see the outline of the thin walls defined by the plywood structures. The tower crane is in the center shaft (which would ride up with the slipform). The orange steelwork is the “yokes†that allowed the rig to yank up the wooden mold walls.

The upper right and lower left images show the “spider network†of steel beams. This steel structure basically held up the wooden molds using “fingers†(yokes) and it was this steel structure which “sat†on the curing concrete before the entire structure was jacked up.

The lower right image shows the structure almost completed. But take note that the end portions were incomplete because Doug Sumner had no idea of how to design that portion of the rig until 5 months into the drawing and construction process. The ends were difficult because the wooden molds needed to be “pulled inwards†to form the tapering legs of the CN Tower. Fortunately Doug came up with a workable design and the entire structure could then start moving upwards on June 26th 1973 with its first bucket pour of concrete.

Slipform Construction - May 1973.jpg
 

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lansd

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June 26th 2013 marks the 40th anniversary of the completion of the CN Tower's concrete "slipform" and the first bucket of concrete being poured. June 26th also coincidentally, was the first public opening for the tower in 1976.

The slipform was used to create the concrete shaft from the foundation all the way to the 1464ft level (which was completed on Feb 22 1974), being jacked up one inch every 5mins. The slipform was designed, engineered and put into operation by Doug Sumner, P.Eng.

The slipform is a wooden form of 2 parallel walls using 4ft high plywood. Construction workers cross-tied rebar into the empty portion of the form, poured concrete into the wooden form, jacked the form upward, and repeated until the entire shaft was completed. The entire slipform structure, and its jacking mechanism, sat on steel rods placed within the curing concrete walls. Concrete is lifted from trucks on the ground to the slipform using a fairly simple and effective cable-hoist system, transferred to human transported wheel barrels on the top platform, and then poured into holes located on the top platform which route the concrete down flexible and moveable "funnels" to the second level where workers hand pour the concrete into the wooden forms.

The slipform had 3 main levels: the top level deck was where the workers carted the concrete via wheel barrels to the holes in the upper desk. The mid-level deck was where the concrete dropped down via a shute into the wooden forms (as seen in the lower-left image above). The lower-level outside and inside decks were where the cured concrete was manually finished off with toweling.

Upwards of 50 men would work in each shift, both on the slipform and on the ground as support personnel. There were 3 shifts per day allowing for continuous concrete pouring for 14 months, except for several weeks due to strikes. No work was done on weekends due to the cost of overtime. Work was done in rain, sleet and snow, regardless of the weather. Note: as a common myth and misconception, the entire shaft was not poured in one continuous run until completed – strikes by workers and weekends would bring the work to a halt.

Slipform Rising - June and July 1973.jpg
 

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Goldie

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This is an amazing story of an amazing Canadian engineering achievement - thank you, lansd!
 

vking

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When the tower was being built my father use to bring my brother and I every week to see how construction was doing and he would take pictures of every stage of it. My brother made a scrapbook of this... We looked high and low for this book in my parents basement and attic but to no avail...We later found out my mother had thrown it out. This book was loaded with pictures! Too bad :(..
 

someMidTowner

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When the tower was being built my father use to bring my brother and I every week to see how construction was doing and he would take pictures of every stage of it. My brother made a scrapbook of this... We looked high and low for this book in my parents basement and attic but to no avail...We later found out my mother had thrown it out. This book was loaded with pictures! Too bad :(..

It seems moms have been throwing out clutter that would have become valuable for generations. My father never shuts up about how his mom threw out his issue of Action Comics #1, which has since been valued at over $2 million because she never saw any potential for future value. Just think of all the obsolete electronics that we throw out now, and how in 30 years future hipsters will be buying the cameras of today in trendy vintage stores in the same way that I go nuts over cameras from the 70s and 80s
 

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