Council shall create and maintain a Capital Improvement Reserve Fund, and may from time to time transfer or appropriate thereto moneys accruing to any other fund of the municipality not needed for the purposes of such fund and available for transfer under general law, and also the unencumbered balance remaining in the General Fund of the municipality at the end of any fiscal year. Moneys in the Capital Improvement Reserve Fund shall not be expended for any purpose except to purchase equipment, apparatus or other property, or to construct buildings, structures, roads and other public improvements needed for the use of the municipality, or to pay bonded obligations of the municipality by means of transfer to its bond and interest retirement fund.