In order to pay the cost required by any purchase, construction, lease, or condemnation of property and equipping of facilities, or the enlargement of presently owned facilities, or to pay a portion of the cost of facilities purchased or constructed pursuant to the Offstreet Parking District Act, a city of the first 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 may be issued at an interest cost to maturity set by the city council and 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 amount of bonds which the issuing city of the first class 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 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 in this section.