Subject to the provisions of Section 17 hereof, the Authority may at such times as it deems expedient transfer and sell the fee simple title, or such lesser estate as the Authority may have acquired, to all or any part of the real property within the designated area not disposed of in accordance with Section 18 hereof and not required for the construction, operation and maintenance of a railroad terminal, Terminal Facilities and approaches thereto, to any individual, association, or corporation, organized under the laws of this State or of any other State or country upon such terms and conditions as the Board of Commissioners may determine, to be used in accordance with an approved plan of redevelopment as hereinabove provided. To assure that the real property so sold is used in accordance with the approved plan of redevelopment, the Authority shall inquire into and satisfy itself concerning the financial ability of the purchaser to complete the redevelopment in accordance with the approved plan and shall require the purchaser to execute in writing such undertakings as the Authority may deem necessary to obligate the purchaser: (1) to use the land for the purposes designated in the approved plan, (2) to commence and complete the building of the improvements within the periods of time which the Authority fixes as reasonable, and (3) to comply with such other conditions as are necessary to carry out the purposes of this Act. Any such area may be sold either as an entirety or in such parcels as the Authority shall deem expedient. It shall not be necessary that title be acquired to all real property within the designated area before the sale of a part thereof may be made as provided herein.
     The proceeds from the sale of any real property by the Authority, pursuant to this Section shall be placed in a sinking fund to be created by the Authority for the retirement of bonds issued pursuant to this Act.