No bridge for the use of the traveling public located as provided in Section 65-25-3 shall hereafter be constructed and operated by any county, municipal corporation, or political subdivision of the state, or by any person, copartnership, association, or corporation, and no franchise shall hereafter be granted for the operation of a ferry within fifteen miles of any toll bridge for the acquisition or construction of which bridge revenue bonds shall have been authorized under this article, except under a written permit granted by the state highway commission. No such permit shall be granted by the state highway commission until it shall ascertain by an investigation, including a hearing upon such notice and under such rules as the commission may prescribe, that there is an urgent public need for the operation of such bridge or such ferry, and that its operation will not affect the revenues of any bridge purchased or constructed under the provisions of this article so as to impair the security of any bridge revenue bonds issued for the acquisition or construction of such bridge.