The further line with the name 'Dreiseenbahn ' makes an elegant curve to pass now the opposite side of the Titisee.

In the direction of Titisee, where the line branches off to Neustadt and then, no longer electrified, on to Donaueschingen, it now goes slightly downhill. In Hinterzarten there is a crest of the line at 893 meters. A few kilometers further on, the route crosses the Ravenna Gorge on a 40-meter-high viaduct. The highlight is the passage at the so-called Hirschsprung, where, according to legend, a stag escaped its hunters by jumping the few meters across the narrow valley. Looking out of the window, you think you can touch the rock walls. After about 15 km, the valley becomes narrower and narrower and lives up to its name. Between Freiburg and Neustadt, a total of nine tunnels are traversed. The Höllentalbahn or three-lake railroad from Freiburg to Titisee and Seebrugg/ Schluchsee (51 km) is almost continuously single-tracked. Georgen) and in the 900 m long Hattingen Tunnel (between Immendingen and Engen). On its way from north to south, the line crosses the European watershed (Rhine/Danube) twice in a tunnel: in the 1,697 m long Sommerau Tunnel (between Triberg and St. In Donaueschingen, the Black Forest Railway meets the Höllental Railway, from Freiburg the second most important railroad line in the Black Forest after the Black Forest Railway. Behind Villingen, the line leaves the Black Forest and crosses the Baar plain.

A few kilometers after Sankt Georgen the Danube source river Brigach is reached, which the route follows for the next few kilometers. The 'Dreibahnenblick' near Triberg offers a good overview of the route. In the steepest and also most worth seeing part of the ascent, the valleys are repeatedly extended. Afterwards, the train passes several hairpin bends with numerous tunnels until it reaches Sankt Georgen, overcoming several hundred meters in altitude. The town of Hornberg itself is crossed on an impressive viaduct. Slowly the valley becomes narrower, Black Forest houses accompany the traveler.

In Hausach, the route changes to the Gutach valley as far as Hornberg. At Haslach, the track passes the dammed side arm of the Kinzig for a few hundred meters, a popular photo motif on windless days due to the reflections. Up to Hausach the railroad follows the Kinzig, at Gengenbach partly even directly on its banks. The Black Forest Railway connects Offenburg with Donaueschingen (100 km).

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