Intersection of Streets. On any corner lot no visual obstruction, including but not limited to, fences, shrubs and trees, between two and one-half (2½) feet and eight (8) feet in height, but excluding street signs, utility poles or traffic signs, shall be erected or maintained upon a property, within the triangle formed by the intersection of center lines of intersecting street right-of-way lines adjacent to the corner lot and a line projected between points on each of those adjacent center lines for a minimum distance of thirty (30) feet from their intersection.