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New Ebensfeld-Erfurt Line, Sandberg Tunnel

The German Unity No. 8 transport project relates to the route in a south-north direction linking Nuremberg, Erfurt, Leipzig/ Halle and Berlin. The VDE No.8.1 part-section is the Ebensfeld- Erfurt connection, in which the construction lot 3230 is located. This section of the route is to be found some 20 km to the south of Erfurt in the Ilmkreis to the west of the small town of Traßdorf and the municipality of Niederwillingen and runs partially parallel to the A 71 federal motorway, which is undercut by the tunnel with 45 m of overburden. The work to be performed in this section involves the construction of the 1,320 m long, twin-track Sandberg Tunnel including emergency exit, shaft building, rescue zones at the portals and linking the rescue zone accesses to the public road network. In stratigraphic terms, the mined part of the tunnel is located in Middle Mottled Sandstone with intermitting sandstones and mudstones, with the former clearly dominating. The ground is weakly fissured to compact. The free groundwater table is to be found beneath the tunnel floor. The vault was provided with a single-layer plastic waterproofing membrane (umbrella seal). The ingressing underground water is to be transferred to the base filter via the "Kammerdrain" geo drainage system. The relief and overflow system, which is connected above the "Kammerdrain" at the annular gap between the outer shell and the waterproofing, is linked to the DN 150 relief line via a siphon. The underground water that collects in this line is transferred to the drainage for the open section at the deeper lying north portal. The siphon effect is intended to prevent the danger of scale accumulating as happened in part in the case of other DB tunnels. The block lengths for the permanent lining in the running tunnel amount to 12.50 m. ln the portal zones, the block lengths are adjusted in accordance with RIL 853. The portals were produced in watertight concrete. Current fire and catastrophe protection requirements were taken into account when the Sandberg Tunnel was planned. On the surface, an emergency exit building with a two-winged escape door and safety lock is to be set up. The running tunnel and emergency exit building are linked by the 95 m long rescue gallery, whose exit is equipped with locks and storage space. The rescue zones at the north and south portals and the emergency exit building are to be fitted with extinguishing water containers with 100 m³ capacity. Driving operations began in July 2000 from the north with a staggered crown/bench/floor excavation using a tunnel excavator. The crown was broken through in the south in May 2001.The remaining bench/floor drive was subsequently tackled. There was no need for the "Kammerdrain" and the overflow system as was shown by the hydrological assessments during the tunnel drive and the considerably lower incidence of water (0.45 l/s on average), which contrasted with the initial specifications relating to the tunnel drainage system in its final state. The ingressing underground water is collected radially and lengthwise by means of napped membrane strips and transferred to the base filter via drainage seepage slots beneath the verges in the running tunnel. From that point it is passed into the groundwater in the form of seepage water (kf≥1,5 ∙10¯⁶m/s)  over the length of the tunnel. The permanent lining was installed in the tunnel from the north as from June 2001. Work on the emergency exit began parallel to the concreting Operations in the running tunnel (floor and vault).The permanent lining and the portal structures were completed in May 2002 so that construction was over in August 2002 after the rescue zones had been produced.


  • Country: Germany
  • Region: Thuringia
  • Tunnel utilization: Traffic
  • Type of utilization: Main-line rail
  • Client: Deutsche Bahn AG, represented by DB ProjektBau GmbH, NL Südost, PZ Erfurt
  • Contractor: Walter Bau-AG, Jäger Bau GmbH, Herzog Bau AG
  • Main construction method: Trenchless
  • Type of excavation: Excavator
  • Lining: Concrete formwork
  • No. of tubes: 1
  • Tunnel total length: 1,320 m, including 1,280 m produced by mining means, 40 m by cut-and-cover
  • Cross-section: excavation approx. 126 m², operation 92 m²
  • Contract Volume: € 18.6 million
  • Construction start/end: July 2000 to August 2002
  • Opening: 2015