Two options were examined to achieve the exit of the Danube valley in the direction of Hegau. One option was to leave the valley near Geisingen, the other choice was to exit near Immendingen. Gerwig chose the latter option, as it turned out to allow for less complex track construction. He chose to artificially lengthen the route with two double slings in the Gutach valley near Triberg. Due to the many tunnels on a curved alignment, the section between Hornberg and Sankt Georgen ended up being the most complicated section of the route, and was completed last.