The provisions of this article shall not apply to signs established pursuant to governmental authority or used for the identification of public buildings, facilities and activities sponsored by a governmental authority or of any official character, such as traffic regulation devices authorized by the Vehicle and Traffic Law of the State of New York, civil defense warning signs, railroad crossing designations, bus stop signs and any other sign authorized and required under federal, state or local law or which contains information required and designed for the protection and safety of the general public, such as danger areas, work areas, utility warnings, safety warning devices and similar notices.