A clear vision triangle, as defined in Section 18.70.050, shall be maintained on the corners of all public and private property around the intersection of roadways or of a roadway and a railroad. The clear vision triangle shall contain no trees, shrubs or other plantings; no fences, walls, signs or other temporary or permanent sight obstructions of any nature exceeding thirty-six inches in height above the existing centerline elevation of the adjacent roadway, except that trees exceeding thirty-six inches in height may be permitted if all branches and foliage be removed to a height of nine feet above the existing centerline of the adjacent roadway. (Ord. 597 § 1, 1997: Ord. 523 § 1(part), 1989)