Idaho Code § 49-1009
The board, the governing board of a county, city or highway district is authorized to contract with any individual, firm or corporation, state or federal agency or any combination of parties, to build, rebuild or maintain or contribute financial aid to the building, rebuilding or maintenance of any section or sections of a highway to any standard necessary for the transportation by private or contract trucks principally engaged in the transportation of products originating or produced in Idaho, to permit the hauling of heavier gross weights and wider loads than now provided by law, to an extent necessary to accomplish that maintenance or construction. Upon application of any of the above mentioned parties for permission to use and operate private or contract trucks for hauling greater gross weights and wider loads than provided by law, the board, county, city or district may make and enter into an agreement with the applicant permitting the overload and providing for payment of an additional financial contribution or an agreement to maintain, build or rebuild the highway for the additional or extraordinary use, specifically providing where necessary, for reasonable protective restrictions. If in the opinion of the negotiating officials, a bond should be required, then a surety bond shall be furnished. Nothing in this chapter shall be construed to require any public agency to enter into these contracts or agreements.
Idaho Code § 49-1009