The department shall have authority to purchase, lease, employ, or acquire by other means, all needed road materials, machinery, equipment, supplies, services, and labor necessary for the construction, reconstruction, maintenance, and control of the state highway system and all tools and materials necessary to keep such machinery and equipment in repair. The department shall also have authority to lease, purchase, construct, or cause to be constructed, buildings for office accommodations, which are necessary in the administration of the duties of the department, and buildings for the storing and housing of materials, machinery, equipment, and supplies; Provided, that the department may not construct or cause to be constructed any building exceeding a cost of one hundred thousand dollars without the consent of the Legislature. The maintenance, protection, and control of the materials, machinery, equipment, supplies, tools, and buildings shall be under the authority and responsibility of the department.