On Thursday morning, disruptions affected several S-Bahn lines around Berlin's Friedrichstraße station due to a signal failure. Technicians discovered the cause to be a rail break on the track between Potsdamer Platz and Nordbahnhof. This break has rendered the affected track unusable, leading to significant delays and restrictions. Specifically, the S1 line is operating at a reduced frequency of every 20 minutes from the opposing track between Potsdamer Platz and Nordbahnhof. The exact cause of the rail break remains unknown, and there is no estimated time for when the service will be fully restored.