(a) An authority may maintain a feasibility study fund. The fund is a revolving fund held in trust by a banking institution chosen by the authority and shall be kept separate from the money for a transportation project.
(b) An authority may transfer an amount from a surplus fund established for a transportation project to the authority’s feasibility study fund if the remainder of the surplus fund after the transfer is not less than any minimum amount required by the bond proceedings to be retained for that transportation project.

(c) Money in the feasibility study fund may be used only to pay the expenses of studying the cost and feasibility of a transportation project, the design and engineering of a transportation project, and any other expenses relating to:
(1) the preparation and issuance of bonds for the acquisition and construction of a proposed transportation project;
(2) the financing of the improvement, extension, or expansion of an existing transportation project; and
(3) private participation, as authorized by law, in the financing of a proposed transportation project, the refinancing of an existing transportation project or system, or the improvement, extension, or expansion of a transportation project.
(d) Money spent under Subsection (c) for a proposed transportation project must be reimbursed from the proceeds of revenue bonds issued for, or other proceeds that may be used for, the acquisition, construction, improvement, extension, expansion, or operation of the transportation project.
(e) For a purpose described by Subsection (c), an authority may borrow money and issue promissory notes or other interest-bearing evidences of indebtedness payable out of its feasibility study fund, pledging money in the fund or to be placed in the fund.