The arch is taking shape: Interior construction Riedberg Tunnel A9.

Currently, the Volken Group, as part of a consortium consisting of Frutiger AG and Prader Losinger AG, is constructing the interior of this highway tube near Gampel-Steg. The inner ring is a self-compacting concrete that is AAR-resistant (chemical reaction that can lead to cracks) and resistant to frost and de-icing salt. The construction of the tunnel vault from around 73 m3 of concrete is demanding, as all the pressure has to be absorbed by mobile formwork - a formwork carriage.