[E18] An introductory video for the renewal work on the Takaiwayama Tunnel Joshin-Etsu Expressway has been released!

On Thursday, May 15th, NEXCO EAST Nagano Construction Office (Nagano City, Nagano Prefecture) released an introductory video for the Takaiwayama Tunnel renewal construction work being carried out on the E18 Joshin-Etsu Expressway in Gunma Prefecture.
Please take a look!

Renewal work on Takaiwayama Tunnel Joshin-Etsu Expressway

This construction project aims to improve stability by installing an invert to create a cylindrical structure as a countermeasure against road surface upheaval in the Takaiwayama Tunnel on Joshin-Etsu Expressway.
This tunnel is close to the Usui Karuizawa Interchange (hereinafter referred to as "IC"), and it was predicted that severe traffic congestion would occur if lane restrictions were implemented, especially on holidays during the tourist season. Therefore, the construction schedule for the tunnel reinforcement work was carefully managed, and the work was carried out only on five weekdays. Since construction began in February 2021, it took about four years to install the 135m long tunnel invert, and the work was completed in March 2025.

You can check out the videos that have been released so far below.

Joshinetsu Joshin-Etsu Expressway Construction Site

This preventive maintenance work involved removing a 70m-high boulder located above the Kitanomaki Tunnel (Kitnomaki, Matsuida-cho, Annaka-shi, Gunma Prefecture) between the Matsuida-Myogi IC and the Usui-Karuizawa IC on Joshin-Etsu Expressway, in order to eliminate the risk of future rockfalls.

Joshin-Etsu Expressway Yomogidai Construction

This work involves installing box culverts on the Expressway and building a filling embankment on top of them as a landslide prevention measure on the long, heavy earthen slope between Sakaki IC and Koshoku JCT on the Joshinetsu Joshin-Etsu Expressway (Sakaki Town, Hanishina District, Nagano Prefecture).