Hestenberg Tunnel - L697

The regional highway 697 starts in Attendorn and runs via Plettenberg to the B 229 to the east of Neuenrade. In Plettenberg it elf it links the parts of the town lying in the north and south with the town Centre. Furthermore together with the L 561 it is the most important road accessing the A 45 for the Plettenberg area. Through constructing a bypass the negative effects on traffic safety were to be removed and the urban development of the town Centre furthered. To come to terms with the forecast volume of 18,000 vehicles per day using the 734 m long tunnel a RQ 10.5T standard cross-section according to RABT was selected. By and large the alignment in the tunnel consisted of an arc. The gradient is at its highest point within the tunnel and from here it falls at 0.55 % towards the south and at 1.8% towards the north. The evacuation tunnel, which extends the entire length of the main tunnel, is parallel to it. The evacuation tunnel's cross-section possesses a horseshoe shaped clearance profile of 2.55 x 3.00 m. It is linked with the main tube by means of cross-passages set at 90 m gaps. The geology of the ground that was penetrated is made up of all kinds of rock layers, which fill out the tunnel cross-section to varying degrees and alternate in the longitudinal direction of the tunnel. Quaternary colluvium up to 3 m thick is encountered at the portals. This is underlain in the southern sector by finely grained sandstones belonging to the Siesel Layers, which contain thin beds of argillite. The Siesel Layers are separated towards the north from the Remscheid Layers, which constitute irregular intermittent beds of sandstones, silt stones and clay schist. After a further fault there are layers of lower and upper Mühlenberg Sandstones. The tunnel largely is located in water-bearing rock. At one time ore mining took place in the tunnel's catchment area so that old workings were to be reckoned with. Given the prevailing ground conditions the NATM (using drill+blast) was selected for producing the main tunnel and evacuation tunnel by mining means. The excavated cross-section was divided into crown and bench. The tunnel possesses a two-shell lining with an umbrella seal. The outer shell constitutes a combination of shotcrete, reinforced concrete matting, steel arches and an anchoring system. The inner shell produced as a watertight concrete structure (WUB-KO according to ZTVING Part 5) is executed in quality C 30/37 exposed concrete. The evacuation tunnel was lined with a 15 cm thick shotcrete shell and additionally secured with anchors and lances. To avoid water pressure load on the shotcrete shell 50 cm wide drainage mats were laid between the shotcrete and the rock at 2 m intervals over the periphery. The tunnel tube was driven from the north portal with a crown excavation followed by a bench heading. A short counter- drive took place from the south portal. The evacuation tunnel was driven as a full-face excavation both from north and south. The operating technical furnishing and the actual operation of the tunnel are commensurate with RABT 2006 specifications.

Country: Germany
Region: North Rhine Westphalia
Tunnel utilization: Traffic
Type of utilization: Road Tunnel
Client: Land of North Rhine Westphalia
Consulting Engineer: Prof. Wittke Beratende Ingenieure, Aachen/Landesbetrieb Straßenbau NRW; RNL Südwestfalen
Construction monitoring: Müller+Hereth, Freilassing/Landesbetrieb Straßenbau NRW; RNL Südwestfalen
Contractor: Züblin AG, Stuttgart/ Strabag
Main construction method: Trenchless
Type of excavation: Drill-and-blast
Lining: Shotcrete/Concrete formwork
No. of tubes: 1
Tunnel total length: 734 m
Cross-section: 80 m²
Contract Volume: approx. 25 mill. Euro (roughwork, road building, tunnel furnishing)
Construction start/end: January 2004 till April 2006
Opening: 2006