No sign shall be erected so as to obstruct the vision of vehicular traffic, or at any location where it may interfere with, or be confused with, any traffic signal or device. No sign or sign structure shall be erected within the vision triangle of a corner lot property measured (20 feet along the property line from the intersection of two streets or 15 feet from the intersection of a street and alley). [Ord. 3790 § 5, 2006; Code 1970 § 17.09.030.]