The tunnel's western portal, located in the middle of a residential area in Alt-Weil, is in the city of Weiler.

The structure initially runs straight from southwest to east, then curves to the right and comes within about 11 meters of the Swiss border.

The east portal, located in a wooded and impassable area, is also in the town of Weiler, just a few meters from the city limits of Lörrach.

[5] The railroad between Weil and Lörrach, planned as a strategic route to bypass Switzerland, required a tunnel through the Tüllinger Berg, which separates the two towns, because of their border location and the unavoidable intersection of the villages.

The Oberländer Bote reported on December 23, 1887:[6] "Construction of the new line has now begun on this side of the Tüllinger Berg and a number of workers are currently busy laying the track bed from Baseler Chaussee to the Wiese.

[7] The construction costs were estimated at 1 million marks, of which almost 40% was for earth and rock moving work and a good half for the lining and vaulting.

[8] The comparatively short construction time for the tunnel can be explained by the strategic military importance of the structure in terms of being able to relocate armed forces to this part of the country.

[9] Towards the end of World War II, on April 23, 1945, the Tüllinger Tunnel was to be blown up by a demolition squad because of the approaching French troops.