N.J. Stat. § 27:16-12
When a county road is in need of extraordinary repair, construction or reconstruction, the public body of the county charged with its care shall prepare specifications and any plans and cross sections necessary to explain and describe the extraordinary repair, construction or reconstruction, contemplated, and forward them to the state highway commissioner. The specifications, plans and cross sections may include and provide for a paved surface of a type different from the existing road, either in materials or method of construction, or in width, and may also include and provide for guttering, curbing, the substantial reduction of grades or other matters incidental or appurtenant to the paved surface. The commissioner may in his discretion approve of such specifications, plans and cross sections, and certify the amount of state moneys he will set aside for the repair of such roads. On its approval and issue of certificate, as provided in article 2 of chapter 14 of this title (s. 27:14-2 et seq.) such public body shall advertise for bids and otherwise proceed as directed by said article 2.
If the commissioner shall fail, for thirty days after the receipt by him of the specifications, plans and cross sections, to certify and set apart any state moneys for such extraordinary repair, construction or reconstruction, or shall within said thirty days, notify such public body of his refusal or inability to make such appropriation, the public body may forthwith proceed to make the extraordinary repair, construction or reconstruction to such road, in accordance with the specifications, plans and cross sections submitted, and may award a contract for the doing of the work, after having first advertised for bids therefor as provided in chapter 25 of the title Municipalities and Counties (s. 40:25-1 et seq.). The extraordinary repair shall be made or the road shall be reconstructed, or construction undertaken under the supervision of the engineer of the county.
If the county shall not have sufficient funds with which to pay for the cost of such extraordinary repair, construction or reconstruction, or its share thereof, such public body of the county may issue certificates of indebtedness and bonds in the manner provided by law in a sum not exceeding the amount of the cost of such extraordinary repair, construction or reconstruction or its share thereof.
N.J.S. § 27:16-12