§ 84. Construction or reconstruction of any road or highway in connection with projects on the principal secondary and feeder roads. The commissioner of transporation may, upon the request of a county through its board of supervisors, include in any project on the federal principal secondary and feeder road system, any work of construction, reconstruction or improvement of any road or highway that is located within the boundaries of such county and that is or shall form a continuation or extension of any such principal secondary and feeder road or shall be in connection therewith. Whenever the commissioner of transportation shall approve such a request of a county, he shall cause surveys and plans to be made either by the county or by the department of transportation. Estimates of the construction and engineering costs shall be made and submitted to the commissioner of transportation for approval. If approved, such county shall thereupon deposit such estimated amounts of monies with the comptroller, who is authorized to receive and accept the same for the purpose of this section, subject to the draft or requisition of the commissioner of transportation. Upon the completion and acceptance of the construction work, the commissioner of transportation shall render to the board of supervisors of such county an itemized statement showing in full the amount of money deposited by such county with the comptroller as hereinbefore provided and all expenditures made for the construction and engineering work connected therewith made pursuant to this section. Any surplus money shall be paid to such county on the warrant of the comptroller on vouchers therefor approved by the commissioner of transportation.