Yamanashi Prefecture/New Misaka Tunnel Construction 2013: Geological Survey, Preliminary Design for Light Sections, etc.
April 21, 2025
Route Plan (from Yamanashi Prefecture Presentation)
Yamanashi Prefecture, which plans to build the "New Misaka Tunnel" on National Route 137, will conduct geological surveys and preliminary designs for light-rail sections in fiscal 2025, as well as make efforts to publicize the plan through public meetings and other means. The construction start date has not yet been decided, but the company plans to announce the tentative schedule when there is a clear prospect of land acquisition. The plan is to build a new tunnel about 100 meters lower than the current Misaka Tunnel. The prefecture will continue to discuss technical issues with experts.
The purpose of the new tunnel is to facilitate the passage of increasingly large logistics trucks, including the fact that the current tunnel was completed more than 50 years ago and is showing significant signs of deterioration, as well as sharp curves before and after the tunnel. The prefecture announced the proposed route in March 2020.
The name of the route is National Route 137. The planned section is from Kawaguchi in Fujikawaguchiko Town to Fujinoki in Misaka Town, Fuefuki City. The planned length is about 5.5 km, and the tunnel length is about 4.6 km (the current tunnel is 2,778 m long). The vertical gradient inside the tunnel is about 1%. The plan is to connect the Yamamiya Tunnel on the Fujikawaguchiko side, a section that has already been developed, in a nearly straight line to the entrance to the Kamui Misaka Ski Resort on the Fuefuki City side. Upon completion, the travel time through this section is expected to be halved from about 10 minutes to about 5 minutes.
On the technical side, the New Misaka Tunnel Construction Evaluation Committee on National Route 137 (chaired by Professor Sunagaya Shinji of Tokyo Metropolitan University) met five times to resolve issues. They exchanged opinions on how to handle intersections with fault zones, high pressure, and large amounts of seepage, measures for areas with large amounts of soil, results of hydrological and geological surveys, and confirmed points to note when making detailed designs. Preliminary design for lighted sections has begun, and the prefecture will accelerate the project's implementation.
When the proposed route was announced, Nagasaki Governor Kotaro commented, "The construction of the new tunnel will alleviate concerns about freezing and snow accumulation. We hope that it will ensure a solid road that can be used to accommodate increasingly globalized cargo traffic and as an evacuation and rescue route in the event of a large-scale disaster such as an eruption of Mt. Fuji."
