Not until 2006 was comprehensive electrification and renovation work carried out as part of the development of the Freudenstädter Stern regional network.

Finally the line was integrated into the Karlsruhe Stadtbahn network and once again after a decade a direct link to Stuttgart was introduced.

The line runs to the south-west through the Horbe district, passing through some low forests and glades to Bittelbronn.

Running mainly west, the line crosses three large viaducts over the valleys near Dornstetten-Aach, Freudenstadt-Grüntal and Freudenstadt-Wittlensweiler to Freudenstädt Hauptbahnhof, which is in the southern part of the town.

The section of the line has numerous tunnels, and unlike the portion between Eutingen im Gäu and Freudenstadt, is not electrified.

It would connect the Württemberg capital of Stuttgart with the Black Forest and future railway lines in the Murg and Kinzig valleys.

Any problems due to a 1.56 km long section through Hohenzollern territory between Bittelbronn and Schopfloch had been resolved by a provision covering this possibility in a treaty between Württemberg and Prussia agreed on 13 March 1865.

[3] The Economic Committee of the Second Chamber stated, that "Württemberg [with the Gäubahn] is preparing to join the ranks of our competitors [especially Baden] on the route to the St.

Moreover, the Gäu Railway would result in an almost straight route which cuts through the kingdom from one end (Freudenstadt) to the other (the border at Crailsheim).

Morlok himself described the necessary large-scale cuttings through the wet rock formations at Schopfloch and the construction of the Ettenbach Viaduct at Wittlensweiler as particularly difficult.

At the end of the 1920s, construction began on a branch line to the Gäu Railway, which would run from Dornstetten via Dornstetten-Hallwangen to Pfalzgrafenweiler.

[4] A few days before the end of the Second World War and four hours before French troops invaded Freudenstadt, the Wehrmacht blew up the three timber viaducts of the Gäubahn.

[4] The popularity of long-haul destinations and the shift of traffic to road transport, among other things, led to a sharp decline in passenger numbers in the 1960s.

These provided for cost reductions through the greatest possible rationalisation of personnel and infrastructure, the introduction of an integraled timetable and services at least every hour.

One of the last projects of the regional network was the electrification of the Gäu Railway in 2006 as well as the construction and reconstruction of the crossing stations at Schopfloch and Hochdorf.

In order to improve the connection of the population of the eastern Freudenstadt district to the railway on the model of the Murg Valley Railway, new stations are planned in Freudenstadt-Grüntal, Dornstetten-Aach, Dornstetten Mitte (as a replacement for the old station), Horb-Heiligenfeld and Eutingen im Gäu Nord.

On the hour between these services, the Albtal-Verkehrs-Gesellschaft (AVG) has extended Stadtbahn lines S 8 and S 81 (Karlsruhe–Freudenstadt) to run to Eutingen on behalf of Deutsche Bahn.

In 2007, the AVG established an operations shed for passenger and freight rolling stock at Freudenstadt Hauptbahnhof.

In addition to the fares of Deutsche Bahn, tickets of the Verkehrs-Gemeinschaft Landkreis Freudenstadt (vgf) are valid on the entire Gäu Railway.