The 4th Elbe Tunnel Tube in Hamburg
Between November 1995 and December 2003, Wayss & Freytag Ingenieurbau AG completed the „4th Elbe Tunnel Tube“ in Hamburg in a joint venture. The tunnel was driven with a mix-shield, which was the largest in the world at that time, under extremely difficult geological conditions – consolidated sands with enclosures of alluvial mud, marly till with water-filled sand lenses and layers of rubble with erratic blocks of up to 2 m in size. For the first time, a SSP-System (Sonic Soft Ground Probing) integrated in the cutting wheel was used to investigate the soil in front of the TBM, so that it was possible to locate and visualise on the screens any erratic blocks and other interferences in good time.
The tunnel, with a total length of 4.4 km between the districts of Othmarschen and Waltershof, consists of a 3.1 km long tunnel section; the tunnel of the 2.5 km long tube was carried out by a mix-shield Ø 14.20 m with a minimum ground cover of only 7 m. The cutting wheel consisted of five main and five secondary arms with a total of 111 scraper knives and 31 roller bits.
The structure is one of the safest tunnels in the world. During a fire, an innovative smoke detraction system extracts the dangerous smoke gas close to the fire source, since there are exhaust flaps every 60 cm. The tunnel lining was carried out with extremely heat-resistant fire-protection panels. Emergency bays, fire alarms and fire-fighting systems are available at regular intervals. The tunnel is under video surveillance 24 hours a day and a tunnel fire brigade is also permanently on duty.