Ems-Dollart Crossing

Currently a tunnel is being constructed below the River Ems near Emden in the direction of the Netherlands to adapt gas transportation in Europe to future requirements and circumstances. After completion the tunnel will accommodate a 48 inch large gas pipeline. The 4,016 m long tunnel starts at the German town of Knock, passes below the Ems and finishes up at Borgsweer in the Netherlands. The shipping passage of the Ems is 12 m deep where the tunnel undercrosses the river. Here the tunnel axis lies 23.5 m below sea level. The tunnel's maximum gradient amounts to 5 % shortly after the starting shaft. The tunnel route is located in the Ems estuary in various quaternary, glacial and post-glacial non-cohesive, cohesive and organic soft ground deposits. The overburden above the tunnel varies from approx. 4 m in the vicinity of the target shaft to approx. 17m on the Dutch bank of the Ems. The distance between the tunnel roof and the bed of the Ems amounts to some 11.5 m. The maximum water pressure in the tunnel floor amounts to roughly 3 bar at high water. The starting shaft for the drive is located on the German bank of the Ems. It possesses a maximum depth of 8 m and consists of sheeting walls and a base made of underwater concrete. On account of the prevailing geological conditions the tunnel excavation is carried out as a hydro shield drive. A pressurised bentonite suspension in the extraction chamber is applied to support the face. The Suspension is pumped to the access shaft together with the excavated material. There the suspension and the excavated material are separated from each other in a specially developed facility. The suspension is prepared and reutilised. The excavated material is deposited close to the construction site. A reconditioned TBM with a length of almost 13 m and 3.78 m external diameter is being used for the excavation. The trailers were completely replaced and are altogether some 80 m in length. The tunnel's external diameter amounts to 3.60 m and the internal one is 3 m. The tunnel is lined with segments with a ring consisting of 5 segments, which are 1.2 m wide and 0.25 m thick. Steel fibres are used as reinforcement. In order to facilitate spatial curves and compensate for driving tolerances universal rings with 30 mm conicity were applied. The segments are transported from the segment factory by train to the intermediate storage depot at Emden and then carried to the site by lorry. The tunnel excavation began in spring 2009. In early summer 2010 work is due to start on inserting the gas pipeline so that gas can be carried through the line in October 2010. The tunnel will be completely backfilled prior to it becoming operational so that it is no longer accessible. No servicing of the gas pipeline's outer jacket has been foreseen.

Country: Germany
Region: Dutch-German Border at Emden, Lower Saxony
Tunnel utilization: Utilities
Type of utilization: Gas Pipeline Tunnel
Client: Nederlandse Gasunie
Consulting Engineer: Wayss & Freytag Ingenieurbau AG, Technical Department, Frankfurt am Main/OSP Consulting Engineers GmbH, Munich (steel fibre reinforced segments)
Test engineer: Dr. Binnewies
Construction monitoring: Ingenieurbüro de Ia Motte & Partner GmbH
Contractor: Wayss & Freytag Ingenieurbau AG, Frankfurt am Main/BAM Civiel n.v., Breda
Main construction method: Trenchless
Type of excavation: Shield machine (SM)
Lining: Reinforced concrete segments
No. of tubes: 1?
Tunnel total length: 4,016 m
Cross-section: 10.9 m²
Contract Volume: 46 mill. euros
Construction start/end: June 2008 till September 2010
Opening: October 2010