Nollinger Berg Tunnel (2nd tube)

The Nollinger Berg Tunnel had to be built in conjunction with the High Rhine motorway A 98 Weil am Rhein-Waldshut, contract section Waidhof-Rheinfelden/Karsau and the Rheinfelden link with Switzerland (A 861).The eastern bore together with an approx. 940 m long escape tunnel with 4 cross-passages started operating in December 2002 with directional traffic (Underground Construction in Germany 200, pp. 318/ 319). The 2nd tunnel tube has been opened to coincide with new motorway link (A 861) with Switzerland becoming operational at the beginning of 2006. The 2 separate tubes have a centre distance of approx. 20 to 30 m and are connected by means of 4 cross-passages. The maximum overburden amounts to some 65 m as opposed to approx. 12 m minimum overburden. The clearance width constitutes 2 lanes (each 3.50 m), the marginal strips (0.25 m) and the emergency footpaths (each 10 m). The clearance height amounts to 4.5 m. ln the rock debris zone at the south portal, the western bore was produced over a distance of 45 m using pipe umbrellas and base invert. ln the drained section that followed a standard cross-section without invert with an excavated area of some 87 m² as well as the lay-by cross-section (length 40 m) with an excavated area of around 115 m² was driven over a length of some 520 m. ln the roughly 680 m long pressure water retention zone the excavated area amounted to around 100 m². In the transition area from the drained to the pressure water retaining zone, a retaining ring was set up as ballast in order to avoid the draining effect of the southern tunnel section acting on the underground water balance. The escapeway (standard cross-section approx. 12 m²) that had already been produced over a roughly 940 m long section was mainly excavated in the crown area when the western drive was being tackled. Geologically speaking, the rock and in turn, the tunnelling methods can be split up into 2 sections:

From the south portal till approx. tm 650 chalky-dolomitic layers of Upper Shell - lime and Letten Keuper were mainly encountered, which exist in the form of undisturbed and mostly solid and largely stable rock
From approx. tm 650 to the north portal at approx. tm 1,230 leached out gypsum keuper marl predominates, which more or less tends towards crumbling causing rock deformations and the build-up of water pressure.

On account of the prevailing geological and hydrological conditions a drive using the NATM was chosen for excavating the tunnel. The overall cross-section was tunnelled in 3 part-excavations (crown, bench and partially base invert). In the southern half the rock was mainly loosened by gentle blasting. This area was produced as a drained tunnel with umbrella seal without base invert. In the northern part the rock was loosened via excavator. A base invert is required in this section as it has to retain pressure water. Supporting was by and large, carried out with shotcrete, reinforced concrete mats, steel rock bolts, steel lances, steel arches and in some sectors with pipe umbrellas and face rock bolts. The lay-by within the shell lime was immediately produced as part of the excavation as an open cross-section. The floor slab as well as the plane was produced by a cold milling machine.

Country: Germany
Region: Baden-Württemberg
Tunnel utilization: Traffic
Type of utilization: Road tunnel
Client: Federal Republic of Germany, Land Baden-Württemberg
Consulting Engineer: Bung Beratende Ingenieure, Müller+ Hereth, Prof. Dr.-Ing. Dieter Kirschke
Construction monitoring: Bung Beratende Ingenieure, Müller+ Hereth, Prof. Dr.-Ing. Dieter Kirschke
Contractor: Östu-Stettin, G. Hinteregger & Söhne, Jäger Bau GmbH
Main construction method: Trenchless
Type of excavation: Drill-and-blast/Excavator
Lining: Concrete formwork
No. of tubes: 1
Tunnel total length: 1,260 m; 1,248 m of which driven by trenchless means
Cross-section: 85 m² (drained area), 100 m² (water-retaining area), 115 m² (lay-bys)
Contract Volume: approx. € 23 million
Construction start/end: July 2003 to June 2005
Opening: 2005