Tex. Transportation Code § 451.357: SECURITY PLEDGED.

(a) To secure the payment of an authority's bonds, the authority may:

(1) pledge all or part of revenue realized from any tax that the authority may impose;

(2) pledge all or part of the revenue of the transit authority system; and

(3) mortgage all or part of the transit authority system, including any part of the system subsequently acquired.

(b) Under Subsection (a)(3) an authority may, subject to the terms of the bond indenture or the resolution authorizing the issuance of the bonds, encumber a separate item of the transit authority system and acquire, use, hold, or contract for the property by lease, chattel mortgage, or other conditional sale including an equipment trust transaction.

(c) An authority may not issue bonds secured by ad valorem tax revenue.

(d) An authority is not prohibited by this subchapter from encumbering one or more transit authority systems to purchase, construct, extend, or repair one or more other transit authority systems.

Acts 1995, 74th Leg., ch. 165, Sec. 1, eff. Sept. 1, 1995.