The Board may, in its discretion, use any part of funds available for the construction of state highways in any highway construction district in which any project authorized for toll revenue bond financing by the Board as described in § 33.2-1700 or by the Richmond Metropolitan Transportation Authority as established in Chapter 29 (§ 33.2-2900 et seq.) is wholly or partly located to aid in the payment of the cost of such projects and for the payment, purchase, or redemption of revenue bonds issued in connection with any such project, or in connection with any such project and any one or more other projects. The Board may also, in its discretion, use any part of funds available for the maintenance of state highways, in any highway construction district in which any such project is wholly or partly located, to provide for the operation, maintenance, and repair of any such project and for the payment of interest on revenue bonds issued in connection with any such project, or in connection with any such project and any one or more other projects. In addition, the Board may, in its discretion, use funds under the terms of this section for the emergency operation, maintenance, and repair of the project of the Chesapeake Bay Bridge and Tunnel District and Commission as established in Chapter 22 (§ 33.2-2200 et seq.) in the event of damage to the bridge under a repayment agreement approved by the bond trustee and may also pay to the Chesapeake Bay Bridge and Tunnel Commission, for aid in the maintenance of the project, the same amounts authorized by § 33.2-319 for payments for maintenance to certain towns and cities. If the Board uses any part of the fund available to itself for the construction of highways in the primary state highway system without reference to highway construction districts, commonly called the “gap fund,” for any purpose permitted by this section, it shall not expend in excess of three-eighths of the amount of such fund, including other amounts of such fund that may be expended in the three districts in which such projects are located, provided that in no case shall any of the funds of any highway construction district other than those in which the projects are located be used for the purposes of this chapter.