It is unlawful within the city to construct or maintain or permit to remain any fence, wall or other structure, or any bushes, shrubs, hedge, tree or other growth or any materials or other obstructions except commercial buildings to vision on any corner lot or property exceeding three feet (3') above the street grade within the triangular area formed by the intersecting property lines and a straight line joining the property lines at points which are thirty feet (30') distant from the point of intersection measured along the street lines. (Ord. 229 § 1, 1968)