Where the Planning Board determines that off-tract improvements are necessary for the proper development and utilization of the proposed site or subdivision and the surrounding area, it may require either that such off-tract improvements be installed, or that the developer contribute to the installation of such off-tract improvements. Where the Planning Board has determined that off-tract improvements are required, it shall be a condition of the granting of final approval that such improvements be constructed or that the developer shall make payments toward the ultimate installation of off-tract gutters, sidewalks, water mains, sanitary sewers, storm sewers, culverts, retention basins, monuments and streetlights, all in accordance with the specifications governing on-tract improvements.