N.J. Stat. Ann. § 27:7-19.2

When the State House Commission shall direct the State Highway Commissioner to settle, compromise and adjust any such claim or claims, the settlement shall be evidenced by an agreement executed by the State Highway Commissioner and such county, municipality or corporation, and such agreement shall be binding upon all of the parties thereto upon its execution, delivery and the making of the payment or payments required; provided, however, that such settlement and agreement shall be void unless the terms thereof are complied with within eighteen months after the delivery of such agreement.