R.I. Gen. Laws § 39-18-8
Bonds issued under the provisions of this chapter may be secured by trust agreement by and between the authority and a corporate trustee, which may be any trust company or bank having the powers of a trust company within or without the state. The trust agreement or the resolution providing for the issuance of the bonds may pledge or assign the revenues to be received, but shall not convey or mortgage any transit property or any part thereof. The trust agreement or resolution providing for the issuance of the bonds may contain such provisions for protecting and enforcing the rights and remedies of the bondholders as may be reasonable and proper and not in violation of law, including, without limitation, covenants setting forth the duties of the authority in relation to the custody, safeguarding, and application of all moneys, and conditions or limitations with respect to the issuance of additional bonds. It shall be lawful for any bank or trust company incorporated under the laws of the state that may act as depositary of the proceeds of bonds or of revenues to furnish such indemnifying bonds or to pledge such securities as may be required by the authority. Any trust agreement may set forth the rights and remedies of the bondholders and of the trustee, and may restrict the individual right of action by bondholders. In addition to the foregoing, any trust agreement or resolution may contain other provisions as the authority may deem reasonable and proper for the security of the bondholders. All expenses incurred in carrying out the provisions of the trust agreement or resolution may be treated as a part of the authority's cost of operation and maintenance. Bonds may also be secured by insurance or by letters of credit, or in any other manner deemed appropriate by the authority not inconsistent with the provisions of this chapter, or may be unsecured.
R.I. Gen. Laws § 39-18-8