(a) An obligation issued under this subchapter, and interest on the obligation, must be paid by an appropriation or pledge of all revenue derived from:
(1) one or more projects;
(2) any tolls authorized under Section 1505.113 and collected from the operation of an existing bridge or tunnel; or
(3) both the project and the tolls.
(b) Payment of the obligation may additionally be secured by a mortgage on any project, including a toll bridge or tunnel or reclaimed land.
(c) Any revenue or income derived from one project may be pledged to the payment of an obligation issued to provide for a different project.