1961 Construction of Power Transmission Line across the Naruto Strait
Unconventional Construction Method No One Had Ever Imagined
On June 6, 1961, a power transmission line was constructed across the Naruto Strait between Awaji Island, Hyogo and Tokushima. The construction project was later in the news around the world including in the U.S., Canada and Australia. Balloons were used to lay a power transmission line to the opposite bank across the strait spanning about 1,700m.
Balloons 2.7m in diameter were attached to a messenger wire 9 mm in diameter (weight: about 500kg) at 20m intervals at the bottom of a steel tower in Tosaki, Awaji Island. The wire was towed by a tugboat and extended while allowing the wire to float in the air. The messenger wire was suspended by 77 balloons in total. The red, yellow and pink balloons appeared to be flowers blossoming over the sky of the Naruto Strait. The wire reached the other side of the strait two hours later. The construction project, including the subsequent work, was completed safely and successfully.
Years later, Kazue Kitagawa, president of Sumitomo Electric at that time, stated, “The year 1961 when we launched new products and equipment marked a milestone in our history.” The success of this unique construction project that attracted the attention of the global community was one of the epoch-making events.