About construction of Kumasaka tunnel construction of Joshin-Etsu Expressway (between Toyota Iiyama IC and Shinanomachi IC)

1 History

We received a report from the contractor that the thickness of the lining concrete in the tunnel was insufficient and that there were voids.

As a result, we confirmed that the thickness of the lining concrete was insufficient and that there were voids in some areas.

It was also found that the reason for such a construction failure was that the construction contractor did not report the matters to be reported to us, but carried out the construction at the contractor's own discretion.

2 Tunnel name

　熊坂トンネル 長野県中野市大字永江地内

3 工事請負契約の概要

Construction name
Joshin-Etsu Expressway Kumasaka Tunnel Construction

Contractor
Mitsubishi Corporation, Kitano Construction Co., Ltd.

Construction period
June 22, 2005-December 8, 2007

4 Other

We are currently reconstructing the defective parts and are planning to complete them by the end of March.

In addition, it does not affect the service period of the four-lane Joshinetsu Expressway (between Toyota Iiyama IC and Shinanomachi IC) scheduled for 2009.