The arch is taking shape: Interior work on the A9 Riedberg Tunnel.

The Volken Group is currently working as part of a consortium consisting of Frutiger AG and Prader Losinger AG on the interior construction of this highway tube near Gampel-Steg. A self-compacting concrete is being used as the inner ring, which is AAR-resistant (chemical reaction that can lead to cracks) and can withstand frost and de-icing salt. The construction of the tunnel arch from around 73 m3 of concrete is challenging, as the entire pressure has to be absorbed by mobile formwork - a formwork carriage.