U15 (Berlin U-Bahn)

The U15 is a supplementary line on the Berlin U-Bahn, operating during peak hours on weekdays. It runs along a portion of the U8 line, specifically between Ruhleben and Uhlandstraße. As such, it does not represent a physically separate track or independent route for its entire length. Its purpose is to increase service frequency on the heavily used western portion of the U8 line during rush hour. The U15 designation is primarily used in official timetables and announcements to distinguish these peak-hour trains from the full-length U8 service. Passengers traveling beyond Uhlandstraße need to change to the U8 to continue their journey towards Hermannstraße.