Electric heating for an immersed tunnel in Norway.
The Bjørvika Tunnel is a motorway immersed on European Route E18 in the city centre of Oslo. The tunnel links Festning tunnel in Oslo west with Ekeberg tunnel in Oslo east. The completed tunnel has an unbroken length of 3.7 miles and is the first immersed tunnel in Norway.
To ensure the fast hardening of concrete during the tunnel construction under winter conditions
The immersed part of the tunnel is made up of six elements. Each element is 112.5 meters long, 28–43 meters wide and 10 meters high. The immersed tunnel consists of two tubes, with three lanes in each direction. The tunnel is 1,100 meters long, 675 meters of which are below sea level. The Bjørvika Tunnel is part of the Opera Tunnel complex, which is the interconnected system of tunnels between Ryen and Filipstad.
During its construction, electric heating solutions were used to harden the concrete in roof and walls in the immersed part of the tunnel. A uniform concrete construction may cause a problem, especially during the Scandinavian winter. Electric heating cables were chosen to make sure that hardening process unfolded properly.
A normal concrete hardening process during winter where temperatures often fall below the freezing point was reached due to electric heating solutions that maintained building process under harsh weather conditions.
1,100 meters of tunnels
675 meters of which is immersed