(a) Where no special hazard exists, the following speeds shall be lawful, but any speed in excess of such limits shall be absolute evidence that the speed is not reasonable or prudent and that it is unlawful [for] all types of vehicles:
(1) 25 miles per hour in any business district;
(2) 25 miles per hour in any residential district;
(3) 20 miles per hour at all school zones where 20 mph regulatory signs are posted and state the time periods or conditions during which the speed limit is in effect; such conditions may include when children are present or while 1 or more warning lights flash;
(4) 50 miles per hour on 2-lane roadways;
(5) 55 miles per hour on 4-lane roadways and on divided roadways.
(b) Whenever the Department of Transportation shall determine, on the basis of engineering studies and traffic investigations or upon the basis of a federal law or directive by the Congress or the President, that a maximum speed limit set pursuant to subsection (a) of this section in any particular place on the state maintained highway system is greater or less than is reasonable or safe, the Department shall declare a reasonable and safe maximum limit thereat, which limit shall be effective when posted. Such maximum limit may be declared to be effective either part or all of the time and differing limits may be established for different times of the day, for different types of vehicles, for different weather conditions and when other significant factors differ. Such maximum limits may be posted on fixed or variable signs. Any speed in excess of such displayed limits shall be absolute evidence that the speed is not reasonable or prudent and that it is unlawful.
(c) Penalties for violation of this section are as follows:
(1) Whoever violates this section shall for the first offense be fined $20. For each subsequent offense, the person shall be fined $25. A subsequent violation, before being punishable as such, shall have been committed within 24 months after the commission of the prior offense.
(2) Any person violating this section who exceeds the maximum speed limit by more than 5 miles per hour but less than 16 miles per hour shall pay an additional fine of $1.00 per mile, if such violation is a first offense, or $2.00 per mile, if such violation is a subsequent offense, for each mile in excess of the maximum speed limit.
(3) Any person violating this section who exceeds the maximum speed limit by more than 15 miles per hour but less than 20 miles per hour shall pay an additional fine of $2.00 per mile, if such violation is a first offense, or $3.00 per mile, if such violation is a subsequent offense, for each mile in excess of the maximum speed limit.
(4) Any person violating this section who exceeds the maximum speed limit by more than 19 miles per hour shall pay an additional fine of $3.00 per mile, if such violation is a first offense, or $4.00 per mile, if such violation is a second offense, for each mile in excess of the maximum speed limit.
(d) The Department of Transportation shall designate a maximum speed limit of 65 miles per hour for all portions of Delaware State Route 1 located between the Red Lion Creek and the Appoquinimink River, except for the delineated nonhighway speed toll plaza area. Such maximum limits may be posted on fixed or variable signs. Any speed in excess of such displayed limits shall be absolute evidence that the speed is not reasonable or prudent and that it is unlawful.