New Jersey Statutes Title 27. Highways 27 § 14-30

When a county road or section thereof lies within the corporate limits of a borough, the borough may improve the road or section thereof in the same manner, as nearly as may be, as it could be improved by the board of chosen freeholders under the provision of this article.

The cost of the improvement shall in the first instance be paid by the borough, but the state and county shall, when the road is completed, reimburse and pay the borough such proportionate share of the cost thereof as they would have respectively paid if the road had been improved by the county under this article. The cost shall include interest charges incurred by the borough on temporary loans provided for in section 27:14-31 of this title. The road when improved shall remain a county road.