In order to pay the cost required by any purchase, construction, lease, or condemnation of property and equipping of parking facilities or the enlargement of presently owned parking facilities, a city of the second class may issue revenue bonds to provide the funds for such improvements. Such revenue bonds shall not be payable from any general tax upon the issuing city, but shall be a lien only upon the revenue and earnings of the parking facilities. Such revenue bonds shall mature in not to exceed forty years but may be optional prior to maturity at a premium as provided in the authorizing resolution or ordinance. Any such revenue bonds which may be issued shall not be included in computing the maximum amounts of bonds which the issuing city may be authorized to issue under its charter or any statute of this state. Such revenue bonds may be issued and sold or delivered to the contractor at par and accrued interest for the amount of work performed. If any city of the second class has installed or installs onstreet parking meters, it may pledge all or any part of the revenue of such parking meters, not previously pledged, as security for the bonds authorized under sections 17-163 to 17-173.