If any funds become available from the federal government or otherwise for expenditure in conjunction with county funds for the construction, alteration, repair, or improvement of any county road and the work is to be performed by the department, the state treasurer shall, upon notice from the department, set aside from any moneys in the motor vehicle fund credited to any such county, the cost thereof, together with the cost of engineering, supervision, and other proper items, or so much of the money in the state treasury to the credit of the county as may be necessary for use in conjunction with funds from the federal government to accomplish the work. The work shall then be performed by the department and paid from the money so set aside upon vouchers approved and submitted by the department in the same manner as payment is made for such work on state highways: PROVIDED, That the legislative authority of any such county shall have, by proper resolution, filed in duplicate in the office of the department and approved by it, determined the county road construction, alteration, repair, or improvement to be performed in such county and the same is found to conform in all respects to the requirements necessary for the use of such funds of the federal government.