N.J. Stat. § 27:3-5
The state highway commissioner may contribute to any county for the purposes of this article any money that may come into his hands to be used for construction, reconstruction or extraordinary repairs, and may certify and set forth in writing to the board of chosen freeholders the amount of money he will give for the purpose of providing and maintaining detours, and the manner and method in which the sum so contributed shall be used, and may formulate such rules and regulations for the expenditure of the money as he may deem necessary. Money so contributed shall be used only for the purpose for which it is contributed, and expended under the authority and direction of the board of chosen freeholders of the county to which the contribution is made.
N.J.S. § 27:3-5