Many drivers are not familiar with the traffic sign, which shows a red dot with a directional arrow. Failure to comply may result in fines and penalties.
The signs with the red dot are usually arranged by the local authorities in order to relieve particularly busy routes from traffic jams and accidents. If the "red route" is used, the regional radio stations usually also provide information about the diversions and explain how they work. According to the "Federal Highway Research Institute", the unknown sign is roughly a kind of diversion.