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The CN and John Street Towers
Toronto's largest landmark
The Canadian National Tower, better known as the CN Tower, is perhaps one of Toronto’s most famous landmarks. Completed in 1975, the CN Tower opened to the public in 1976 and was the tallest freestanding structure in the world until 2007. To accommodate the growing number of large condos and apartments in Toronto, Canadian National (CN) constructed the CN Tower to allow for the continued broadcasting of FM radio stations in the downtown core. Originally, the tower was intended to be part of a joint telecommunications subsidiary of both CN and the Canadian Pacific Railway (CPR), but CPR pulled out of the project. Over 1,500 workers helped to complete the tower.
Today, the CN Tower is one of Toronto’s most popular tourist attractions, with over two million annual visitors. The tower also holds annual tower climbs to raise money for charity. To date, the fastest time to complete the climb the Tower’s 1,776 steps was 9 minutes and 54 seconds by Shaun Stephens-Whale in 2017.
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The CN and John Street Towers
Construction begins
Construction of the CN Tower was a huge task. Workers needed to excavate 56 tonnes of rock to make the massive foundation for the building. One of the scariest moments occurred near its completion in March 1975. To install the 335-foot antenna on the top of the tower, workers needed to use a helicopter. Workers nicknamed the helicopter Olga.
Due to stronger than normal winter winds, Olga became tangled in construction cables and supports. With only a few minutes of fuel left, her operator finally untangled the helicopter and landed safely. Workers eventually attached the antenna in April after waiting for better weather.
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The CN and John Street Towers
In the shadow of the giant
In contrast to the CN Tower, the John Street Interlocking Tower is rather unassuming. Located just west of the CN Tower, this brick building is one of several interlocking switch towers operated by the Toronto Terminals Railways (TTR) and controls the signals and switches for rail tracks leading in and out of Union Station. TTR built three interlocking towers along the corridor, with the other two located on Cherry and Scott Streets.
Similar to other railway towers, the John Street Tower is two stories tall with the interlocking mechanism located on the top floor overlooking the tracks. The tower only controls the interlocking for a small portion of the corridor. This 1.3-kilometre area spanned from the tower itself to just west of Spadina Avenue. Workers used a system of loudspeakers to communicate between the towers.
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The CN and John Street Towers
Interlocking at John Street
Interlocking is an important process in busy rail corridors and can be thought of like traffic lights for trains. To ensure trains move safely along the tracks, workers use a series of signals and switches to control the movement of the trains on specific tracks. While labourers constructed the towers, the movement of the tracks required 60 workers manning switches along the corridor.
When the John Street Tower opened, it housed approximately 170 switches that controlled the rail signals. This included a system lights, as well as the mechanism that moved portions of the tracks. As a safety precaution, if certain switches were tripped, they remained locked until the controller switched them in reverse order. One unique aspect of Toronto’s rail lands is that much of the 1930s interlocking system is still intact and, until recently, in daily use by tower controllers.
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The CN and John Street Towers
Additional resources
CN Tower, “The CN Tower story”, 2022.
Dungeon Studio, “Union Station: Trains and Towers” [documentary], 2019.
H.L. Black, “Interlocking system installed at Toronto Union Station”, Railway Signaling, Volume 24(12), 1931.
Metrolinx, “Time in a Box: Union Station prepares to retire a vast interlocking system that’s guided every train in and out of Toronto for almost 90 years “, Metrolinx Blog, 2019
New York Central System, “The Railroad Signal” [documentary], 1948.
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