Emmerauen Tunnel - L614

The L 614 starts at the B 1 in Blomberg, leads on to the B 329 to the west of Schieder and then runs via Lügde to the regional boundary of Lower Saxony at Bad Pyrmont. Owing to the medieval road cross-section in the town of Lügde the 13,120 vehicles per day that pass through this bottleneck make it an unacceptable Situation both for motorists as well as local residents. The choice of a route for the bypass was governed by the town's location in the densely built-up Emmer basin. Between the railway line, town and River Emmer only the floodplains were available for setting it up. However, as the Emmer regularly floods these plains the only possible solution was a tunnel with a gradient protected against flooding. The covered tunnel section is 512.5 m long. A RQ 10.5t tunnel cross- section was selected. The longitudinal gradient in the tunnel amounts to 0.2 % and the clear height 4.95 m. The overburden amounts up to 2 m. The tunnel section crosses a sports ground, a road bridge (K64) and the "little Emmer': The prevailing subsoil is mainly characterised by diluvial and alluvial deposits in the form of ballast, gravel and alluvial clay. In the southern section from the start of the ramp to roughly 140 m into the tunnel mixed grain and sandy fills are to be found at depths of up to 2 m below a thin layer of topsoil. Underneath there are fluvial and alluvial clays up to a depth of 3.9 m. ln addition mud, sapropel and peat were traced. A series of strata several metres thick comprising gravels and sands was encountered underneath. It consists of boulders, gravel and sand of various origins and formation. For instance red mottled sandstones, shelllime, keuper residues as well as quartzite boulders, cemented by silt grains were encountered. In the northern section of the route the topsoil covering is superimposed on extensive fills, which extend down to some 4.80 m below ground Ievel. These are located on the fluvial gravels also present in the southern sect ion, which in part contains a layer of mud. The groundwater is to be found close to the surface and correlates with the Emmer's water levels without any time delay. Owing to the described geological and hydrogeological conditions as well as the proximity to historic buildings that are susceptible to settlement a watertight excavation pit consisting of overlapping bore piles and an anchored underwater concrete floor were created. The pit was divided up into 7 individual sections with lengths varying from 30.5 to 180m. Back anchoring of the excavation pit walls was not feasible on account of the proximity to the river and the town wall so that stiffening was applied. The possibility of the excavation pit flooding during the construction period was taken into account. The tunnel and the troughs were produced as watertight concrete structures in accordance with ZTV-ING Part 5. The tunnel's closed frame structure was executed monolithically at the floor and walls. An evacuation staircase and the operations centre are set up roughly in the middle of the tunnel. The troughs are lined with standard layers of masonry and extended roughly 1 m above ground level for noise protection reasons. The operation technical furnishings and tunnel operation are commensurate with the RABT2006.

Country: Germany
Region: North Rhine Westphalia
Tunnel utilization: Traffic
Type of utilization: Road Tunnel
Client: Land of North Rhine Westphalia
Consulting Engineer: Wesselmann und Brune, Münster/Landesbetrieb Straßenbau NRW ; RNL Ostwestfalen-Lippe
Construction monitoring: Landesbetrieb Straßenbau NRW ; RNL Ostwestfalen-Lippe
Contractor: Strabag AG, Chemnitz Branch Office
Main construction method: Open
Type of excavation: Cut-and-cover
No. of tubes: 1
Tunnel total length: 512.5 m
Cross-section: approx. 90 m²
Contract Volume: approx. 16 mill. Euros (roughwork, road building), approx. 3.5 mill. euros (tunnel furnishing)
Construction start/end: September 2005 till December 2008
Opening: 2009