It leads the Neudietendorf–Ritschenhausen railway beneath the Brandleite massif, a part of the ridge of the Thuringian Forest that reaches a height of 897 m a.s.l.

[1] The tunnel is mostly straight, only at the Oberhof end the tracks curve slightly towards the south.

[4] Plans to dynamite the tunnel in April 1945 were reportedly stopped by the actions of Reichsbahn senior secretary Ernst Kallert (1901-1947).

The Rennsteig road tunnel which was opened on 5 July 2003 crosses above Brandleite tunnel about 350 m from its western end at a vertical distance of 5 ... 6.5 m.[4][5] The effects of its construction, in particular on the water circulation[6] and the upgrade of the railway line for tilting trains were reasons to rehabilitate the aging tunnel during 11 months in 2004/2005, taking significantly longer than the originally planned 5 months.

Corrosion due to the damp atmosphere required frequent repainting of metal parts.

[1] Smoke from steam locomotives therefore tends to accumulate in the tunnel, so that it was referred to as the "forecourt to hell" by railwaymen.