CN Tower Achieved 6-Meter Daily Ascent with Continuous Slip-Form Construction

Toronto, Canada – The construction of Toronto's iconic CN Tower, which reached a height of 553.3 meters (1,815 feet), employed a groundbreaking continuous slip-form concrete pouring technique that enabled the structure to ascend approximately 6 meters (20 feet) each day. This rapid vertical progression, sustained 24 hours a day for months between 1973 and 1976, was a defining feature of the ambitious project. The method was highlighted in a social media post by James Graham, detailing the initial phase of the tower's build.

The slip-form method involved a self-climbing formwork system that allowed concrete to be poured continuously, creating a seamless and incredibly strong central shaft. This engineering feat required meticulous planning and execution, with workers pouring concrete five days a week until February 1974. Vertical accuracy was paramount, maintained by comparing the slip form's position to massive plumb bobs observed from the ground, resulting in a remarkable deviation of only 29 mm (1.1 inches) from true vertical.

While the tweet's title also referenced the Coriolis Effect, experts confirm this phenomenon has a negligible impact on the construction of tall buildings. The Coriolis Effect primarily influences large-scale atmospheric and oceanic systems, causing deflection of moving objects over significant distances, but its forces are not substantial enough to affect the structural integrity or vertical alignment of a tower during its build.

The CN Tower project, undertaken by the Foundation Company of Canada, involved 1,537 laborers and consumed 40,500 cubic meters (53,000 cubic yards) of concrete and 5,000 tons of reinforcing steel. The tower officially opened on June 26, 1976, and held the record as the world's tallest free-standing structure for 32 years, showcasing a triumph of Canadian engineering and construction innovation.