Tunnel Katzenberg is a 9,385 m long railway tunnel on the upgraded and newly constructed line Karlsruhe – Basel. The structure increases capacity and speed of the Rhine Valley Railway thus relieving the towns along the old line from fright traffic.
In the course of the project, 20 km of ballastless track Bögl were constructed. For the first time in Germany, a system that is passable by road vehicles was installed. The track extends beyond the two tunnel portals to the emergency areas. The rail heads protrude only 6 cm from the deck slabs. In the area of underpass Bad Bellingen, the ballastless track is decoupled from vibrations by a medium-heavy mass-spring system on a length of 500 m.