In any triangle formed by the street lines intersecting at an angle of 100 degrees or less, there shall be a comer setback of fifteen (15) feet from the point of intersection, wherein no building or structures may be erected, no parking areas may be created and no vegetation or fencing may be maintained above the height of three and one-half (3 ) feet above the plane of the curb grades. Notwithstanding the provisions of this section, poles not exceeding eight (8) inches in outside diameter designed for the support of lights and signs, may be erected in this triangle.