In case the boards of supervisors of the several counties or if any one of them fail or refuse to erect or cause to be erected such sign or guide boards as provided in Sections 65-7-15 and 65-7-17, then upon a petition to the circuit court by as many as twenty-five qualified electors, who are also taxpayers on real property in the county, joining in said petition, the remedy by way of mandamus shall apply and shall be fully available to enforce the provisions of the said two sections. The said petitioners of the number and qualifications aforesaid shall be deemed to possess all the necessary interest and to be fully entitled to demand, in the proceeding by mandamus, the enforcement by the court of all the duties aforementioned, and the court may upon the trial make all proper orders fully for said enforcement.