Tunnel construction in Japan

The Kobutsu Tunnel of the Chuo Expressway (about 1.6 km downhill and 2.0 km uphill), located at the headwaters between Tokyo and Yamanashi Prefectures, is frequently congested, not only on weekends.

In particular, there is a phenomenon of sagging in front of the tunnel on the uphill road, the downhill slope changes to an uphill slope, when the traffic volume increases, the slight increase or decrease in the speed of the vehicle in front will be transmitted to other vehicles and reduce the overall speed. This is believed to be the cause.

As part of this measure, construction is currently underway to build a tunnel on the upper line and create three lanes in front and behind. The plan is to add a new single-lane tunnel without making any changes to the existing double-lane tunnel and excavation work on the "Shin Kobutsu Tunnel"

When constructing the temporary road associated with the construction of the new Kobutsu Tunnel, the EDO-EPS construction method provided by Ribic Okazo was adopted because the construction in the mountainous area does not allow for a large area and the materials that can be brought in. were limited.
EDO-EPS weighs about 1/100 of the weight of conventional soil and concrete, which is useful for reducing the embankment load on weak ground and steep terrain. Because it is a lightweight component, it can be easily constructed by hand without relying on heavy objects. machinery, etc. can be constructed quickly. In addition, the block-shaped components are easy to handle and facilitate the dismantling of the structure after construction is completed.