Where no special hazard exists on any section of a highway, street or alley which section is not zoned and posted by action of the City Council, the following speeds shall be lawful, but any speed in excess of said limits shall be unlawful, and shall be prima facie evidence that the speed is not reasonable or prudent:
(A) Fifteen mph when passing a school zone, said zone being marked in a conspicuous manner;
(B) Fifteen mph on Main Street; and
(C) Twenty mph on other streets of the city not included in divisions (A) and (B) above.
(Prior Code, § 6-4-2) Penalty, see § 73.99