Stadtbahn Köln, Baulos Deutz-Messe

The geological and hydrogeological conditions in the zone touched on by the Cologne Underground railway system are governed by Rhine deposits from various ages. In undisturbed areas, the following typical formations are to be found:

• high-water surface layer and river bank loam 2-6 m thick
• sands and gravels from the diluvial Rhine Lower and Middle Terraces 8- 30 m thick
• tertiary sands and browncoal clays as from approx. 20.0 m below sea-level, corresponding to a depth of 20-36 m related to the elevation of the terrain.

Initially, when the Cologne Underground system was first being built, efforts were made to steer clear of the groundwater. The tunnel was created directly below the road consolidation and the groundwater pumped away if necessary and fed into the Rhine. Starting with the Rheinufer Tunnel and the Deutz-Messe Underground railway construction lot, underwater concrete bases were usually created without reinforcement. The base was calculated as a plate subjected to stress at one side and as an arch supporting framework. The bending strengths of the plates were restricted. As in the case of reinforced bases, support was provided by cavities included in the curtain wall. Doing away with the reinforcement made work much easier. In addition, the production of the base could largely be mechanised. The combination of curtain wall and underwater concrete base applied since 1974 is known as the wall-base construction method. The two elements create a closed, watertight construction trench system. Interference with the hydrological cycle and in turn, uncontrolled settlements in areas with say, valuable buildings, is excluded. Growing awareness of environ mental considerations and the priority of undisturbed groundwater conditions, practically do not allow any alternative in terms of enclosing the excavation for Underground railway construction sites.

• Country: Germany
• Region: Nordrhein-Westfalen
• Tunnel utilization: Traffic
• Type of utilization: Underground, urban and rapid transit
• Client: Stadt Köln
• Main construction method: Open
• Type of excavation: Cut-and-cover
• No. of tubes: 1
• Tunnel total length: 505 m<input type="image" class="c-inputButton" name="_saveandclosedok" src="http://www.daub-ita.de/typo3/clear.gif" title="Dokument speichern und schließen" />
• Cross-section: 40 m²
• Contract Volume: ca. 80 mill. DM
• Construction start/end: 1979-1981 (24 months)
• Opening: 1981