Maryland Code, Transportation § 4-314

(a) Without in any way limiting or restricting its effect or application, this subtitle is intended to authorize the Authority to finance any one or more or any combination of transportation facilities projects by any one or more or combination of issues or series of bonds secured by the pledge of the net or gross or any combination of the net or gross rentals, rates, fees, tolls, and other charges and revenues derived from any transportation facilities project or combination of projects designated by any bond authorizing resolution or trust agreement securing the bonds.

(b) However, all funds collected from rentals, rates, fees, tolls, and other charges and revenues which are not needed to meet the costs which they are required to meet under § 4-312 of this subtitle or any trust agreement and are not needed to meet obligations of the Transportation Authority Fund, may be used in the discretion of the Secretary to provide adequate and complete payment of all principal and interest on all bonds issued in connection with the John F. Kennedy Memorial Highway and any project constructed under the provisions of Section 3 (Bridge, Tunnel, and Motorway Revenue Bonds) of Chapter 608, of the Acts of the General Assembly of 1976. All such remaining funds thereafter remaining may be transferred, upon the recommendation of the Secretary and after the approval of the Board of Public Works, to the Transportation Trust Fund and may be used for any purpose to which funds in the Transportation Trust Fund may be applied.