Karlsruhe-Basel Line Extension

The Karlsruhe-Basel line is the heart of one of Europe’s most important freight corridors, Rotterdam-Cologne-Basel-Milan-Genoa, and is one of the oldest and most frequently used railway lines in southwest Germany. The demands of modern rail traffic will be met with the continuous four-platform extension to the Rhine Valley line, as well as new railway sections in some areas. WSP provided various planning services with regards to general technical equipment planning.


The Karlsruhe-Basel line extension is of strategic significance to cross-regional, European and international rail traffic. Because of its geographical position, it is part of Europe’s most important freight traffic corridor, Rotterdam-Cologne-Basel-Milan-Genoa.

At over 150 years old, the line between Karlsruhe and Basel, also known as the Rhine Valley line, is one of the oldest and most frequently travelled railway lines in southwest Germany. Over 250 local, long distance and freight trains travel daily along the 182 km double-track line between Karlsruhe and Basel. It has therefore reached its capacity limit. Adapting the lines to meet the demands of current and future traffic is urgently required in light of existing bottlenecks and the resulting quality constraints, as well as the increased traffic expected in years to come.

The Karlsruhe-Basel line extension and new constructions have been conceived with a four-track extension in mind, in order to significantly increase line capacity and reduce travel and transport times.

Maximum Speed
250 km/h 250 km/h
Planning and Construction Costs
€ 12 billion € 12 billion
Signal Boxes
5 5

Focus on overhead contact system planning

The extension of the existing double-track Rhine Valley line to four tracks is for the purposes of increasing capacity. As a rule, the extension is to be carried out by means of creating two new tracks directly parallel to the existing tracks. Each track pair will be managed as individual lines in the future (newly constructed line: line 4280; Rhine Valley line: line 4000). The newly constructed line will be routed for 250 km/h, and the Rhine Valley line rerouted for 160 km/h.

In areas where line management for existing railway routes does not permit the design speed to exceed 160 km/h, the parallel placement between the newly constructed line and the Rhine Valley line will be avoided, and the newly constructed line managed separately.

Plans for the overhead contact line systems will depend on the construction stages:

  • Rhine Valley line extension to four tracks with speed increased to 250 km/h (double-track).
  • Newly constructed line to be continued as a freight bypass on a separate route in plan approval section 8.3.
  • Creation of supply concepts, overviews and rough cost calculations.
  • Design planning with creation of overhead contact line placement plans, taking structural perspectives and alignments into account.
  • Cost estimates. 

The Katzenberg Tunnel: a milestone for extending rail infrastructure in Germany

The Katzenberg Tunnel is the longest two-lane tunnel in Germany, with a length of 9,385 m. WSP’s services involved the planning of the overhead contact line system with the use of a new type of procedure to fix the overhead line. A specially-modified maximum speed overhead contact line (Re330) will be used here for the single-track tunnel, with a segmented structure.

WSP's services included the following:

  • Design planning for overhead contact line technical equipment for the tunnel.
  • Developing all overhead contact line components for integration into the segmented tunnel, such as support points and re-tensioning equipment, in collaboration with construction technology and DB system technology.
  • Plan testing and co-ordinating construction technology plans concerning the overhead contact line.
  • Creating grounding concepts.
View into the Katzenberg Tunnel with fixed track, overhead contact line and safety lighting | WSP

View into the Katzenberg Tunnel with fixed track, overhead contact line and safety lighting

Source: Deutsche Bahn AG

Dismantlement of Müllheim signal box

The Rhine Valley line, which is currently a double-track system, will make use of a new double-track line in order to reduce travel times and allow further capacity. The placement of both new and additional track sections means that the existing Müllheim signal box must be dismantled and replaced with an electronic signal box. The signal boxes of Corridor A (Emmerich-Basel) will also need to be ETCS-compatible in the future. The introduction of ETCS Level 2 is intended for the Müllheim signal box area. The Müllheim electronic signal box A will be connected to the Buggingen electronic signal box exchange centre and the Karlsruhe control centre.

WSP's services included the following:

  • Dismantling the relay interlocking system and constructing the new Müllheim Station electronic signal box A in various construction operating modes.
  • Changes to track plans to create four-track structure.
  • Adapting neighbouring signal boxes (Heitersheim relay signal boxes, Schliengen and Neuenburg electronic signal boxes).
  • Adapting/replacing energy supply concept.
  • Adapting/replacing point heating systems.
  • Adapting overhead contact line system (Re200 model with single mast design).
  • Constructing a new overhead contact line system (Re250 model).