The rail used in construction of all spur tracks constructed on all paved streets subsequent to the passage of this Article shall be T-Rail with inner guard rail as approved by the Department of Public Works or Girder Rail of a standard style. If any spur track now in existence in said City and County shall be reconstructed, in whole or in part, on any paved street, the T-Rail with inner guard rail or standard girder rail as above designated, shall be used in such case.