Property owners must preserve a visual line of sight at intersections to allow for pedestrian and vehicular traffic safety. All fences, walls, hedges, shrubs or trees located on corner lots shall be set back so as not to obstruct the visibility at a street intersection for a distance of fifteen (15) feet back from the property corner at the intersection on both the front and side street frontages. For trees, shrubs and similar appurtenances, the free vision area at the corner shall be applicable from three (3) feet above the curb grade at the intersection to a distance ten (10) feet above the curb grade.