Bad Ems Tunnel

1,540 m long and with a central position in Bad Ems, the tunnel represents the core section of the B 260 Fachbach-Bad Ems bypass. It is located beneath a railway track and a local road on account of the lack of space between the neighbouring built up areas and the railway line. A roughly 30 m high steep slope had to be created at the west portal to obtain some room for tunnelling. This slope is approx. 230 m high with a maximum gradient of up to 45°. Rocky sections of the steep embankment were worked by chisel. Rock cutters were also used. Depending on the orientation of the dividing plane system, fractures were secured either systematically or one by one using rock nails. The steep slope that had to be secured was partly located in scree in a central area. The embankment was supported by means of a multiple anchored shotcrete shell. Altogether, around 35,000 running metres of rock bolts were installed. Securing this slope represents a very challenging engineering task. in order to control slope movements in every working phase, extensive measurements were undertaken using inclinometers, extensometers at geodetic points - and the results compared with previously produced FE analyses. The tunnel is produced by cut-and-cover over its entire length that has to be filled after its completion. The excavation wall was executed in various ways depending on the requirements involved, such as e.g. in the form of an anchored Berlin type support wall, steel sheet wall and drilled pile wall. The various types of wall had to be fixed in place with up to 4 layers of pre-tensioned pressure-grouted bolts. Altogether, it involved the drilling and installation of around 50,000 running metres of rock bolts. The ground conditions at tunnel floor level vary a great deal. Partially the structure is founded directly on rock, elsewhere it is located in extremely soft, pappy soils. Individual blocks had to be set up on concrete drilled piling in addition to flat foundations in order to limit the differences in Settlements of the various blocks. In one section, the soft alluvial loam soil had to be improved using gravel plugs. The tunnel was concreted in blocks in 2 sections. First of all, the base slab and the walls were produced followed by the ceiling. The block length amounts to 10 m. Internal joint strips and a watertight concrete lining assure that the tunnel is watertight. The structure additionally had to be provided with a 3 mm, greatly modified PE membrane to protect it against the groundwater, which acts very aggressively against concrete on account of the proximity of up to 80° hot thermal water.

• Country: Germany
• Region: Rhineland Palatinate
• Tunnel utilization: Traffic
• Type of utilization: Road tunnel
• Client: Federal Republic of Germany
• Consulting Engineer: Bung Beratende Ingenieure, Krebs und Kiefer Beratende Ingenieure für das Bauwesen, ELE Erdbaulaboratorium Essen
• Contractor: Walter Bau-AG
• Main construction method: Open
• Type of excavation: Excavator/Roadheader
• No. of tubes: 1
• Tunnel total length: 1,540 m
• Cross-section: excavation appr. 120 m², width 9,50 m x 4,70 m
• Contract Volume: approx. € 45 million
• Opening: 2006