In the discretion of the Board, each or any issue of revenue bonds may be secured by a trust indenture by and between the Board and a corporate trustee, which may be any trust company or bank having trust powers within or outside of the Commonwealth. Such trust indenture may pledge tolls and revenues to be received, but no such trust indenture shall convey or mortgage any project or any part thereof. Either the resolution providing for the issuance of revenue bonds or such trust indenture 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 covenants setting forth the duties of the Board in relation to the acquisition, construction, improvement, maintenance, operation, repair, and insurance of the projects and the custody, safeguarding, and application of all moneys. Such resolution or trust indenture may also provide that the project shall be acquired, or acquired and improved, or constructed, and paid for under the supervision and approval of consulting engineers employed or designated by the Board and satisfactory to the original purchasers of the bonds issued therefor and may also require that the security given by contractors and by any depository of the proceeds of the bonds or revenues of the project or other moneys pertaining thereto be satisfactory to such purchasers. Any bank or trust company within or without the Commonwealth may act as such depository and furnish such indemnifying bonds or pledge such securities as may be required by the Board. Such indenture may set forth the rights and remedies of the bondholders and of the trustee and may restrict the individual right of action of bondholders as is customary in trust indentures securing bonds and debentures of corporations. In addition to the foregoing, such trust indenture may contain such other provisions as the Board may deem reasonable and proper for the security of the bondholders. Except as otherwise provided in this chapter, the Board may provide, by resolution or by such trust indenture, that after the payment of the proceeds of the sale of the bonds and the revenues of the project into the state treasury the Board will immediately transfer or pay same over to such officer, board, or depository as it may determine for the custody thereof and for the method of disbursement thereof, with such safeguards and restrictions as it may determine. All expenses incurred in carrying out such trust indenture may be treated as a part of the cost of maintenance, operation, and repairs of the project affected by such indenture.