No parking shall be permitted within a front yard setback line established ten (10) feet back of the property line of interior and corner lots wherever the parking lot is located in a residential district or immediately abuts the front yard of a residential unit. In all other cases, no setback shall be required; however, on any corner lot formed by two (2) intersecting streets, no parking shall be permitted, and no wall, fence, sign, structure or plant growth having a height in excess of three (3) feet above the elevation of the crown of the adjacent roadway surface shall be maintained in a triangle formed by measuring a distance of thirty (30) feet along said front and side lot lines, from their point of intersection, and connecting the points to established to form a triangle on the area of the lot adjacent to the street intersection.