The city council of a city of the metropolitan class may issue bonds, as provided in this section, for the purpose of improving lands, lots, or grounds purchased, appropriated, or acquired for parks, parkways, boulevards, or playgrounds. Bonds so issued shall be known as park bonds and the issuance of such bonds except as provided in this section shall be governed by section 14-515. The city council may issue in any one year and without a vote of the electors one hundred thousand dollars of such bonds. The city council may also issue such bonds if authorized by a majority vote of the electors of the city voting on the proposition at a general city election or a special election called for that purpose. A part of the proceeds from the sale of such bonds may be used to pay for improvements upon streets, sidewalks, or thoroughfares abutting upon or immediately adjacent to parks, parkways, boulevards, and playgrounds when such costs would otherwise be chargeable to the city.