Sec. 7-1-42 Exceptions.
   (a)   It shall be unlawful to operate a vehicle in excess of the speeds listed below upon the streets or portions of streets of the stale highway system listed in each designated appendix hereby made a part hereof:
   (1)   Twenty miles per hour (appendix I, section 105)
   (2)   Twenty-five miles per hour (appendix I, section 106)
   (3)   Thirty miles per hour (appendix I, section 107)
   (4)   Forty miles per hour (appendix I, section 108)
   (5)   Forty-five miles per hour (appendix I, section 109)
   (6)   Fifty miles per hour (appendix I, section 110)
   (7)   Fifty-five miles per hour (appendix I, section 111)
   (b)   It shall be unlawful to operate a vehicle in excess of the speeds listed below upon the streets or portions of streets, not a part of the state highway system, listed in each designated appendix, hereby made a part hereof:
   (1)   Twenty miles per hour (appendix I, section 112)
   (2)   Twenty-five miles per hour (appendix I, section 113)
   (3)   Thirlv miles per hour (appendix I, section 114)
   (4)   Thirty-five miles per hour (appendix I, section 115)
   (5)   Forty-five miles per hour (appendix I, section 116)
   (6)   Fifty miles per hour (appendix I, section 117)
   (7)   Fifty-five miles per hour (appendix I, section 118)