Semi-permanent Strand Anchors Stabilize Smoke Removal Structure

Within the scope of the major project Stuttgart 21, approval section 1.5, Lot 3, the Bad Cannstatt Tunnel is being advanced. The approximately 3.8km long railroad tunnel will connect Stuttgart Main Station with the new Neckar Bridge.


In order to provide mechanical ventilation of the tunnel and the station in the event of a fire, several smoke removal structures must be built. This project also includes the smoke removal structure near the intersection of Heilbronner and Moenchhalden Streets. It incorporates a ventilation shaft that will be connected to the tunnel tubes via ventilation galleries. The structure consists of a mainly subterranean operation and ventilation building, two 5m high vent stacks above ground and a staircase.


The excavation was built using a Berlin-type support system and tied back using strand anchors. Construction work is scheduled to take more than 2 years. Therefore, semi-permanent anchors were used instead of temporary anchors because they are suitable for a service period of up to 10 years. An internal company approval from the Client – the Deutsche Bahn AG – was necessary before the semi-permanent DYWIDAG Strand Anchors could be used. As the DYWIDAG Strand Anchors comply with a general technical approval, they were approved by the test association Dr.-Ing. A. Städing, and DYWIDAG’s customer GBS Grundbau received the DB AG’s permission for installing them.

419 semi-permanent Type 4-0.6" DYWIDAG Strand Anchors including anchor heads were installed in the walls of the Berlin-type support system. The strand anchors had a total length of 8,750m and a total weight of 40t.

ProductionSupplyTechnical Support

Joint Venture Tunnel Cannstatt S21, Germany

GBS Grundbau Bohrtechnik Spezialtiefbau GmbH & Co. KG, Germany

Wayss & Freytag Ingenieurbau AG, Germany