The 1.7km extension will provide a direct link between the northern section of Line U2 and Rhine-Main S-Bahn Line S5 and Taunas Line (RB 15) regional services, with a two-minute journey time between Gonzenheim and Bad Homburg station.
As part of the project the current terminus at Gonzenheim will be replaced by a new underground through station on the west side of Gotenstrasse. The line will continue in a tunnel beneath Frankfurter Landstrasse, emerging to the west of the Friedrichsdorf - Bad Homburg line, which the extension will follow on a single-track alignment into Bad Homburg station.
Off-peak headways at the northern end of Line U2 will be reduced from 20 minutes to 15 minutes and the extension will be designed to allow operation of a 7.5 minute-interval peak service.
The €66m project will be 80%-financed by the state of Hessen with the remainder coming from local sources.