Hermann-Hesse-Bahn Althengstett Tunnel Forst

Situation de départ

The Black Forest Railway has been recently reactivated between the cities of Weil der Stadt  and Calw. The Hermann Hesse Railway  has now once again connected Calw to the Stuttgart region. A particular challenge was the 1200 meter long and up to 36-meter deep cutting between Althengstett and Calw, which dates back to 1872.

Its embankments were originally supported at the foot by up to 6 meter high natural stone walls, which in some areas are heavily weathered and are exposed to further erosion. In addition to the stability and economic efficiency, high demands on nature conservation  had to be taken into account during the rehabilitation. The entire cutting area is located in the Black Forest Nature Park.

Géologie

Middle Triassic strata of the Lower Muschelkalk

The region contains the Freudenstadt Formation, which is up to 55 meters thick and consists of clayey, sometimes also sandy dolomitic marls with intercalated harder dolomite layers.

The formation is underlain by an approximately three-meter red clay formation of the Upper Buntsandstein. The layer boundary is recognizable in the terrain by its colors gray-beige (Muschelkalk) to dark red (Buntsandstein).