No person shall operate a motor vehicle on a public highway at a speed of 60 miles per hour or more and at least 30 miles per hour in excess of a State speed zone or local speed limit. A person who violates this section shall be imprisoned upon a first conviction not more than three months or fined not more than $300.00, or both; and upon a second conviction shall be imprisoned not more than six months or fined not more than $500.00, or both. (Added 1989, No. 109, § 5, eff. July 1, 1990.)