The election to determine whether the county road unit system shall be abandoned shall be called by the board of county supervisors upon the presentation of a petition signed by at least ten percent of the qualified electors of the county. Such petition shall be filed by the petitioners with the county clerk. At any such election, the votes shall be taken for and against the county road unit system and if the majority of the votes cast at such election be against the county road unit system, then the county shall be restored to the county and township road system.