It runs from Mannheim via Heidelberg, Bruchsal, Karlsruhe, Rastatt, Baden-Baden, Offenburg and Freiburg to Basel, Switzerland.

The Karlsruhe–Basel high-speed railway, called the Ausbau- und Neubaustrecke Karlsruhe–Basel in German (literally: "Upgraded and new line Karlsruhe–Basel"), has been under construction since April 1987.

The existing Rhine Valley Railway will then be expanded in the Offenburg – Hügelheim section by 2041 for speeds of up to 200 km/h.

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.

A shorter and more direct line from Graben to Karlsruhe via Blankenloch was added in 1895 as a strategic railway.

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.

The signal boxes at Leutersberg, Bad Krozingen, Heitersheim and Müllheim (Baden) have been modified under CIR ELKE and equipped with LZB.

As a result, Deutsche Bahn is building a high-speed line from Karlsruhe to Basel, including new and upgraded sections.

An investigation by the Hochschule Kehl (a school of public administration) estimated the traffic to be up to 286 trains a day.

The double-track high-speed line through the Katzenberg Tunnel between Schliengen and Haltingen has been in operation since 9 December 2012.

[10] As part of the expansion of the operations of the Rhine-Neckar S-Bahn, a three-track section is planned between Mannheim Hauptbahnhof and Mannheim-Friedrichsfeld Süd.

Südwestdeutsche Verkehrs-Aktiengesellschaft and the Breisgau S-Bahn operate Stadler Regio-Shuttle RS1 and Talent 2 EMUs.

In November 2015, the operation of a group of services called Netz 4 Rheintal, was tendered as three lots.

[14] In December 2015, the operational concept of a regional transport timetable between Offenburg and Basel was presented.

In addition, two Regional-Express services would run every two hours: a faster regional train would run every two hours between Offenburg and Basel in less than 90 minutes, with stops in Offenburg, Lahr, Hebolzheim, Kenzingen, Riegel-Malterdingen, Emmendingen, Denzingen, Freiburg Hauptbahnhof, Bad Krozingen, Heitersheim, Müllheim, Weil am Rhein and Basel SBB.

A slower RE would stop in addition at Orschweier, Ringheim, Schallstadt, Bad Bellingen, Efringen-Kirchen and Haltingen.

[14] The target concept for rail services in 2025 of the state of Baden-Württemberg, which provides—three trains each hour and in each direction between Offenburg and Freiburg and four between Riegel-Malterdingen and Freiburg—cannot be implemented because of the congestion of the line.