In each county required to conduct an election under the provisions of section 40-1702, Idaho Code, there shall be established a local highway study commission. The local highway study commission in each county shall be composed as follows:
(1) One (1) member shall be appointed by the highway district commissioners of each highway district within the county;
(2) The mayor of the city with the largest population within the county shall appoint one (1) member;
(3) The chairman of the county commissioners shall appoint a county commissioner as one (1) member and that member will serve as chairman of the commission.