What does this traffic sign indicate?

This sign indicates a diversion route for autobahn (motorway) traffic, marked with a "U" followed by a number. It is used when you have to leave the autobahn due to closures, traffic jams, or construction. Drivers should follow the sign to rejoin the autobahn later or bypass the blockage. It does not indicate a subway station or a federal road. Recognizing and correctly following these diversion signs ensures smooth detours on the autobahn network.