Like the bowling enthusiast Hanada, Sato Kinichi, a famous tunnel man at the Seikan Tunnel, also came to Kyushu.
I heard that he was passionate about the fact that now that the world's longest undersea tunnel, the Seikan Tunnel at 53km, has been excavated, the only project remaining is the 235km Japan-Korea undersea tunnel.
Satokin (Kinichi Sato), who was an expert at using side dump loaders at the Seikan Tunnel, was able to carry it and enter Karatsu (in reality, he transported heavy machinery such as a long horizontal boring machine, side dump loader, and compressor that he had won at auction from the Seikan Tunnel by ship from the Tsugaru Strait to the Tsushima Strait).
Based on geological surveys conducted over a five-year period starting in 1982, a comparison route for Japan-Korea tunnels was drawn, and an inclined shaft base (approximately 200,000 square meters) was constructed in Karatsu, Saga Prefecture.
The entrance to the inclined shaft is opened, the pier, rails, and winch are installed, and it's finally Satokin's turn.
He excavated a total of 400 meters of inclined shaft without any accidents, with the first phase of construction being 200 meters and the second phase being 200 meters. (Currently, the third phase of construction, 150 meters, has been completed, and the inclined shaft length is approximately 550 meters. The target length is 1,200 meters.)
Furthermore, the biggest challenge in the aforementioned topographical and geological survey was to conduct a geological survey of the deep areas beneath the seafloor, including the unconsolidated sedimentary layers that extend more than 500 meters below the seafloor of the Tsushima Strait, so a research vessel conducted acoustic surveys (single and multi-channel) using sparkers and water guns over a distance of 16,000 km.
The person who guided us behind the scenes was Mr. Yuzo Takeuchi, who served as the section chief for the Seikan-Hankan and Kyushu-Shikoku Straits Lines. Mr. Takeuchi was the deputy director of Tappi at the time of the Seikan Tunnel flooding accident.
Additionally, we received full assistance from Engineer Takeishi of Hakodate in the design and modification of the research vessel (Teiyan Maru, 150 tons).
Through his connection with the sonic surveys conducted by these research vessels, Takeuchi is now acting as a matchmaker for Engineer Takeishi's eldest son.
We were also assisted with surveying and construction by surveyor Shintani from Hokkaido and architect Kawase.
The most impressive survey was the cross-sea survey of the Iki Channel (30km of sea area from the Karatsu area of Saga Prefecture to the Iki area of Nagasaki Prefecture), which was the second cross-sea survey using optical waves in Japan after the Seikan Tunnel.
Everyone really cooperated without any compensation, with the strong desire that the next step after the Seikan Tunnel would be the Japan-Korea Tunnel!
