The driver of a vehicle or streetcar (other than a light road vehicle that is not a bicycle; the same applies hereinafter in this Article) must sound the horn:
when about to proceed through a blind intersection, around a blind curve, or over a blind summit at a place designated by a road sign or marking;
when about to proceed through a blind intersection, around a blind curve, or over a blind summit when on a stretch of road designated by a road sign or marking as a mountain road or road with many curves.
The driver of a vehicle or streetcar must not sound the horn unless required to do so pursuant to laws and regulations; provided, however, that this does not apply if sounding the horn is necessary in order to prevent a hazard.