work week a train owned by the Albtal-Verkehrs-Gesellschaft travels between Freudenstadt, Eutingen, and Herrenberg, where it connects to the S-Bahn. On the section Rottweil-Tuttlingen, the Ringzug of the Hohenzollerische Landesbahn provides local service. The Stadler Regio-Shuttle RS1 travel on the Gäubahn at least hourly under the week, and every other hour on weekends. Between Engen and Singen service is provided every 30 minutes by the Seehas of the type Stadler FLIRT, which is today managed by SBB GmbH, a subsidiary of the Swiss Federal Railway. Every other hour, the RE-trains of the DB AG, which travel on the Black Forest Railway (Baden) between Karlsruhe and Konstanz, provide additional service between Engen and Singen, using double-decker coaches powered by class 146 locomotives. Freight traffic The Gäubahn is again becoming a significant railway in terms of international freight traffic, particularly as an alternative to the heavily traveled Rhine Valley Railway, primarily as a transit route. With the exception of the connecting line to the industrial area of Böblingen-Hulb, no freight is processed for shipment directly on the line. Railion trains travel primarily from the large shunting station near Kornwestheim to St. Margrethen in Switzerland, and go around Stuttgart Hbf. This was accomplished until the 1970s via the Pragtunnel, Bahnhof Stuttgart-West, and a connection loop, but has been handled since the opening of the Stuttgart S-Bahn by running freight trains via the Rankbach Railway (Rankbachbahn) from Kornwestheim via Leonberg to Böblingen and the Gäubahn. Railion mostly utilizes the class 185 locomotives. Operational challenges Notwithstanding the sizable reductions in trip times in the last decades, the Gäubahn is still a comparatively slow line, largely due to the single-track section between Horb and Hattingen. Particularly in the section between Tuttlingen and Rottweil, the single track is used by ICE, Regional-Express, freight traffic, and the Ringzug, which leads to numerous times where Ringzug trains have to stop at the stations in Wurmlingen, Spaichingen, and Aldingen to await a train traveling in the opposite direction. Even ICE trains have to make a scheduled stop in the industrial station in Epfendorf to await oncoming traffic. In Stuttgart, the scheduled ICE service misses the important ICE connections to Berlin and Dortmund by a few minutes, which makes these ICE connections less attractive. The Gäubahn is also challenged by the modernized Bundesautobahn 81. Plans for the future Reestablishment of twin-track configuration The reestablishment of the Gäubahn in a twin-track configuration