No person shall erect or maintain a sign on or overhanging public property or a public right-of- way, nor shall any sign extend over an adjoining property line; provided, however, that governmental signs, and signs erected by a public utility company and approved by the City which are necessary for public safety are exempt from this section. The City may erect banners which overhang public property or a public right-of-way as provided in Section 18.03.030. No person shall erect any sign so as to interfere with or restrict access to windows, fire escapes, or required exits. No person shall erect any sign which constitutes a safety hazard as determined by the City.