In order to utilize to the greatest extent possible the benefits of available financial resources relating to transportation purposes, including federal grants, loans, transportation facility revenue sources, and other programs, the Department from time to time may issue its bonds and otherwise borrow funds, as provided in this subtitle, to finance the costs of transportation facilities. The Department may apply for any financial assistance in support of projects deemed appropriate by the Secretary. The Department may undertake the following actions and do all things necessary and appropriate consistent with such actions to utilize the available resources specified in subsection (a) of this section: Pledge and use existing and anticipated federal funds paid to or expected to be paid to the Department for transportation purposes for the payment of the principal of and interest on the Department’s bonds or other debt obligations issued under this subtitle to finance the costs of transportation facilities; and Borrow funds from the federal government or its agencies, and evidence such borrowing with a promissory note or other evidence of obligation; Borrow funds from a nongovernment lender if the loan is guaranteed by the federal government or its agencies; and Use the proceeds of the loans described in items (i) and (ii) of this paragraph in connection with transportation facilities including use of the proceeds to pay the costs of financing transportation facilities and the payment of debt service on the Department’s bonds issued in connection with such transportation facilities; Repay the loans with revenues attributable to the transportation facilities being financed; and Pledge revenues attributable to the transportation facilities being financed in order to secure the Department’s obligations to the federal government or its agencies or a nongovernment lender in connection with the loans. If the Department intends to pledge any future federal aid from any source to support repayment of bonds issued under this subtitle: The aggregate outstanding and unpaid principal amount of debt issued under this subtitle or Title 4, Subtitle 3 of this article that is secured by a pledge of future federal aid may not exceed $1,000,000,000 as of June 30 of any fiscal year, provided that the proceeds may be used only for: Designing and constructing the Baltimore Red Line; Procuring zero–emission buses consistent with § 7–406 of this article and constructing related infrastructure, including bus maintenance facilities; Developing and constructing the Southern Maryland Rapid Transit Corridor; Designing and constructing improvements to the Maryland Route 2 and Route 4 corridor, including the Thomas Johnson Bridge; Designing and constructing improvements to the Maryland Route 90 corridor; Designing and constructing improvements to the Interstate 81 corridor; or Major rehabilitation of the existing light rail system, including replacement light rail vehicles and related station and maintenance facility improvements; The date of maturity may not be later than 15 years after the date of issue; and No part of the tax levied under § 3–215 of this title may be repealed, diminished, or applied to any other purpose until: The bonds issued under this subtitle and interest on them have become due and fully paid; or Adequate and complete provision for payment of the principal and interest has been made. By resolution of the Secretary, the Department may: Borrow funds to finance the costs of transportation facilities; Evidence the borrowing by the issuance and sale of revenue–backed bonds; and Pledge and use a dedicated revenue source, which may include revenues attributable to the transportation facilities being financed, for the payment of the principal of and interest on the Department’s revenue–backed bonds described in this subsection. Payment of the principal of or interest on revenue–backed bonds issued under this subtitle may not be supported directly or indirectly by State tax revenues pledged to meet debt service on Consolidated Transportation Bonds as prescribed under § 3–215 of this title.