Two-track railway tunnel. VDE 8.1 new railway section Ebensfeld – Erfurt, BA 3121, VP Coburg Ost, NBS Bau-km 19,1+30 – 24,8+95

The road project Coburg East is part of the road traffic master plan Deutsche Einheit Nr. 8.1, new highway Nürnberg-Erfurt-Leipzig/Halle-Berlin.
The contract embraces a 5.8 km long stretch including the tunnel Feuerfelsen 1’003 m, the tunnel Rennberg 1’032 m, five bridges, the roadwork and earthwork of 2.2 mill. cubic meter.

Execution and schedule :
The tunnels are realized with a two shell in-lining, being the outer shell of shotcrete and the inner one of concrete. The tunnel section has 160 m2 and both tunnels are excavated simultaneously. The excavation is realized applying the conventional NATM. Works started in August 2010 with the excavation of the trench of the Southern portal of the tunnel Feuerfelsen. The tunnelling work started in January 2011. For the completion of both tunnels a schedule of 21 months was set.

Length: 1 x 1’003 m
1 x 1’032 m
Excavation volume: 320’000 m³
Shotcrete/concrete volume: ca. 170’000 m³
Arming steel inner shell: ca. 8'000 t
Construction method: NATM
(D&B with heading, bench and bottom)
Pull length: max. 2,2 m
Diameter of the tube: 12 m
Minimal covering: 10 m
Maximal covering: 25 m
Escape gallery L = 150 m and escape shaft
Planned speed-limit: 300 km/h

Both tunnels Feuerfelsen and Rennberg are driven on their whole length through formations of coloured sandstone. The tunnels have a covering of 10 to 25 meters. Due to ground water the construction is shielded with a KDB insulation.