No tollway project shall be undertaken unless and until the tollway project involved shall have been thoroughly studied with respect to traffic, engineering, costs, and financing, and unless the authority involved makes, by resolution entered in the records of that authority, a determination based upon the study that:
(1) Sufficient public funds for construction of the proposed tollway are not available; and
(2) The construction of the proposed tollway can be financed wholly through the investment of private funds in revenue bonds.