The Fortress Tunnel, part of the Oslo Opera Tunnel, will be closed overnight for over a year due to rehabilitation.
From Monday, the tunnel will be closed in one direction at night. The work is scheduled for completion in November 2020.
The fortress tunnel is 1,764 meters long, and its lowest point is 45 meters below sea level.
The tunnel is one of the oldest tunnels in Oslo and is the western part of the E18 Operational Tunnel through the center of Oslo.
© NTB Scanpix / #Norway Today