(b) Any person violating the provisions of this section is guilty of a misdemeanor and, upon conviction thereof, shall be fined not more than one hundred dollars; upon a second conviction within one year thereafter, shall be fined not more than two hundred dollars; and upon a third or subsequent conviction, shall be fined not more than five hundred dollars.
(c) No provision of this chapter for which signs are required shall be enforced against an alleged violator if at the time and place of the alleged violation an official sign is not in proper position and sufficiently legible to be seen by an ordinarily observant person. Whenever a particular section does not state that signs are required, such section shall be effective even though no signs are erected or in place.