(1) Whenever the Department of Transportation determines, upon the basis of an engineering and traffic investigation, that any speed is greater or less than is reasonable or safe under the conditions found to exist at any intersection or other place, or upon any part of a highway outside of a municipality or upon any state roads, connecting links or extensions thereof within a municipality, the Department of Transportation may determine and declare a reasonable and safe speed limit thereat which shall be effective when appropriate signs giving notice thereof are erected at the intersection or other place or part of the highway.
(2)(a) The maximum allowable speed limit on limited access highways is 70 miles per hour.
(b) The maximum allowable speed limit on any other highway which is outside an urban area of 5,000 or more persons and which has at least four lanes divided by a median strip is 65 miles per hour.
(c) The Department of Transportation is authorized to set such maximum and minimum speed limits for travel over other roadways under its authority as it deems safe and advisable, not to exceed as a maximum limit 60 miles per hour.
(3) Violation of the speed limits established under this section must be cited as a moving violation, punishable as provided in chapter 318.