N.J. Stat. § 40:56-11: Work done by municipality or by contract

All work or any portion thereof in connection with any local or general improvement may be done either by the municipality or by contract awarded to the lowest responsible bidder. Advertisements for bids for the doing of any such work shall be published and the bids shall be received and the contract awarded in each municipality in accordance with the provisions of chapter 50 of this title (s. 40:50-1 et seq.).