Baden main line The railway on the German side of the Rhine was financed and built by the
Grand Duchy of Baden State Railway (
Großherzogliche Badische Staatsbahn). At the enactment of the Baden law permitting the construction of the
Baden main line on 28 March 1838, only the starting point in Mannheim and the end point in Basel had been determined. The route was determined by the
Technischen Baukommission (“Technical Building Commission”), which was formed in 1837. It adopted as its basic aims that the construction cost should be as low as possible as was consistent with good running times and that the line should be built as straight as possible to connect the major cities. It decided that the should be built, if possible, in the
Upper Rhine Plain. The first section between
Mannheim and
Heidelberg was opened in 1840 and the line was completed in several section to Basel until 1855. The first route designs provided for a route from Heidelberg via
Schwetzingen to Karlsruhe. After the then third largest city in the
Grand Duchy of Baden,
Bruchsal learned of these plans, the Baden Parliament sat to consider a connection via Bruchsal and
Durlach. On 2 January 1846, two trains ran into each other in St. Ilgen, a village near
Leimen. One person died and 16 others were injured. This was one of the first fatalities in a rail accident in Germany. The line was originally built to , but since the surrounding countries built their railways to , the line was converted to standard gauge between 1854 and 1855. Since
Schwetzingen and
Hockenheim were not on the line through Heidelberg, another line was opened in 1870 on the Mannheim–Schwetzingen–Graben–Eggenstein–Karlsruhe route. A shorter and more direct line from Graben to Karlsruhe via Blankenloch was added in 1895 as a
strategic railway. This converted the Karlsruhe–Eggenstein–Graben section of the old line into a branch line, now known as the
Hardt Railway and partly incorporated into the
Karlsruhe Stadtbahn.
Developments in the 20th century In the northern section between Mannheim and Karlsruhe there are two different lines, the Mannheim–
Graben-Neudorf–Karlsruhe line (the Baden Mainline as such) as well as the Mannheim–Heidelberg–Bruchsal–
Durlach–Karlsruhe line (the
Baden-Kurpfalz Railway). Particularly after
World War I it became a major line for international traffic. Beginning in the 1950s, the Rhine Valley line was progressively electrified, with the line fully electrified by the middle of 1958. In the late 1960s, a fundamental renewal of signaling installations began on the 120 km-long section between Offenburg and Basel. The line, which was previously equipped with
mechanical interlockings—with the exception of
Freiburg Hauptbahnhof—was converted to control by
relay interlockings. By the late 1960s the line was already being used by well over 100 trains per day in each direction. With the commissioning of the first section of the
Mannheim–Stuttgart high-speed railway between Mannheim and
Graben-Neudorf, the Rhine Valley Railway was relieved, making an integrated regular interval service possible. The signal boxes in
Achern and Freiburg were built as
electronic interlockings. The signal boxes at Leutersberg,
Bad Krozingen,
Heitersheim and
Müllheim (Baden) have been modified under
CIR ELKE and equipped with
LZB. The current
Baden-Baden station was originally called Oos, between 1906 and the closure of the old Baden-Baden town station in 1977 it was called Baden-Oos and then it received its current name.
Developments in the 21st century As part of the construction of the
Karlsruhe–Basel high-speed railway, it was planned in 1990 to upgrade the railway between Karlsruhe and Offenburg for continuous operations at 160 km/h. Under a German-Swiss convention, the entire line was supposed to be converted to at least four lines by 2008, so that it could serve as the main northern approach route to the new
Gotthard Base Tunnel line to Italy. As a result,
Deutsche Bahn is building a high-speed line from Karlsruhe to Basel, including new and upgraded sections. Between Karlsruhe and Rastatt two lines run relatively near each other, effectively providing four tracks. The double-track section between Rastatt station and Rastatt-Niederbühl is to be increased to four lines with the construction of the
Rastatt Tunnel. Between Rastatt-Niederbühl and Offenburg, two new high-speed tracks have been completed next to the old double-track line. A new section of line from
Schliengen to Haltingen between Freiburg and Basel, including the
Katzenberg Tunnel, was opened on 9 December 2012 to avoid a narrow, winding section between the
Rhine and the Isteiner Klotz hills. The remaining sections between Offenburg, Freiburg and the Katzenberg Tunnel are still being planned. ==Operations==