Mem­bers of the Sheriff’s Depart­ment, Spe­cial Deputies, and Aux­il­iary Deputies assigned to traf­fic duty are here­by autho­rized to direct all traf­fic in accor­dance with the pro­vi­sions of this Code or in emer­gen­cies as pub­lic safe­ty or con­ve­nience may require, and it shall be unlaw­ful for any per­son to fail or refuse to com­ply with any law­ful order, sig­nal or direc­tion of a police­man.  Except in cas­es of emer­gency, it shall be unlaw­ful for any per­son not autho­rized by law to direct traf­fic. (See 625 ILCS Sec. 5/11–203)