(b) Any person who exceeds any posted speed restriction or traffic restriction at a construction site referred to in subsection (a) of this section by less than fifteen miles per hour is guilty of a misdemeanor and, upon conviction thereof, shall be fined not more than two hundred dollars.
(c) Any person who exceeds any posted speed restriction or traffic restriction at a construction site referred to in subsection (a) of this section by fifteen miles per hour or more is guilty of a misdemeanor and, upon conviction thereof, shall be fined not more than two hundred dollars or confined in a county or regional jail not more than twenty days, or both.
(d) Nothing in this section shall be construed to preclude prosecution of any operator of a motor vehicle who commits a violation of any other provision of this code for such violation.