The geological structure of the Finne Tunnel
In this section, the new line crosses over from the Thuringian Basin, a geological downwarping structure, to an area known as Hermundurische Scholle, which has a structure caused by shifting tectonic plates.
These formations are separated by the Finne fault, where the Buntsandstein comes up against the Keuper.
The highly disjointed rock formations of the Finne fault pose a considerable yet surmountable challenge on account of the geological and hydrological situation. Moreover, parts of the tunnel are up to 50 metres below the groundwater level.
Extensive investigations were carried out before construction work began on the tunnel. The latest technology was used, including analysis of aerial photographs and pulse echo technology. 100 bore holes to a depth of almost 100 metres provided drilling cores. Investigations of the rock and water continue to be carried at every step of the way during tunnel construction.