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Eichelberg Tunnel

The sixth and last tunnel as part of the A 71, the Eichelberg Tunnel, was built between the Meiningen-Süd and Rentwertshausen junctions. The north portal for the 2 tubes, which pass below the Eichelberg nature protection area over 1,110 m (eastern tube) and 1,120 m (western tube) at a distance of 25 m, is located immediately to the south of the Meiningen-Süd junction. The tunnel is set in a dome, with the route from the south portal rising at a maximum of 4% reaching its high point roughly a third of the way along the tunnel. Each tube is being provided With a 750 m wide carriageway made of concrete and 2 emergency footpaths each 1 .0 m 10,74 9.50 wide. The clear height amounts to 4.50 m. The tunnels are linked to each other by 3 cross-passages, one of which can be used by vehicles. In addition, 2 lay-bys are installed in each bore. Both tubes were driven simultaneously from the north and south by drill+blast and by excavator using the NATM. The concrete permanent linings are set up on foundation verges throughout. Flat base inverts, however, were installed in the 2 portal areas. The shotcrete outer shell and the reinforced concrete permanent lining are separated by fabric and a sealing membrane. Any underground water present is collected in the wall drainage systems at the foot of the verges and transferred to the portals unpressurised. Stable slotted PE pipes with a white, co-extruded inner shell as signal layer, electro welded at the joints and enveloped with cement-bonded drainage gravel were installed. The north and south portals are cut to the level of the embankment fill and covered with red coloured elements to form collars. The tunnel is fitted with jet fans to provide longitudinal ventilation, which serves to ventilate it in standard mode and in the event of fire. It is controlled via visibility and CO measuring points as well as via the fire alarm installations. Mottled sandstone layers are to be found below the lower shell lime around the Eichelberg. The tunnel passes through the following formations:

  • Upper mottled sandstone - red pelite layers
  • Upper mottled sandstone - myophoria layers (roughly 20 m thick)
  • Lower shell lime/well bedded limestone.

Inclinometer measurements revealed that the high embankment at the eastern flank of the north portal is prone to landslides. Thanks to additional exploratory bores a slipmodel was devised and suitable ways to secure it discussed. Ultimately, rock bolts in 3 layers were selected on account of their robustness, which are protected against corrosion and installed in the rock. Inclinometer bores will be continued for some time to come with sensors in order to observe any subsequent slope movements and confirm the stability. Excavators began working in March 2003 in order to produce the cutting in front of the north portal. At the same time, the steep wall of the embankment was secured by means of rock bolts and shotcrete. Driving started in July with the excavation of the crown from the north. In late autumn, the southern cutting had also been cleared away and secured to such an extent that the counter-drives from the south could start. The mined driving operations were concluded when the final cross-passage was created in May 2004. Waterproofing and the reinforced concrete permanent linings were installed from June 2004 to February 2005.


  • Country: Germany
  • Region: Thuringia
  • Tunnel utilization: Traffic
  • Type of utilization: Road tunnel
  • Client: Federal Republic of Germany, Land of Thuringia
  • Consulting Engineer: DEGES Deutsche Einheit Fernstraßenplanungs- und -bau GmbH, Bung Beratende Ingenieure
  • Examination: Prof. Dr.-Ing. Dieter Kirschke
  • Contractor: Dywidag SF- und Ingenieurbau GmbH, Walter-Heilit Verkehrswegebau GmbH
  • Main construction method: Trenchless
  • Type of excavation: Drill-and-blast
  • Lining: Concrete formwork
  • No. of tubes: 2
  • Tunnel total length: 1,110 m (eastern tube), 1,120 m (western tube)
  • Contract Volume: € 43 million for roughwork, € 6 million for operating installations
  • Construction start/end: March 2003 to June 2005 roughwork, July 2005 to December 2005 operating installations
  • Opening: December 2005