No fence, structure or plant over 30 inches in height shall be erected or maintained that will or could obstruct traffic visibility. The minimum clear corner area of the property shall be a triangle, two sides of which shall be coincident with the street right-of-way lines, with each such side having a length of 25 feet measured from the point of intersection of said lines, or such other shape as may be determined by the Township agency to be an appropriate geometric design. Shade trees trimmed to a height at least 10 feet above the street pavement shall be permitted within said clear corner area.