((a)) The Department of Transportation has an administrative working capital fund. Amounts in the fund are available for expenses of operating and maintaining common administrative services the Secretary of Transportation decides are desirable for the efficiency and economy of the Department. The services may include—

((1)) a central supply service for stationery and other supplies and equipment through which adequate stocks may be maintained to meet the requirements of the Department;

((2)) central messenger, mail, telephone, and other communications services;

((3)) office space;

((4)) central services for document reproduction, and for graphics and visual aids; and

((5)) a central library service.

((b)) Amounts in the fund are available without regard to fiscal year limitation. Amounts may be appropriated to the fund.

((c)) The fund consists of—

((1)) amounts appropriated to the fund;

((2)) the reasonable value of stocks of supplies, equipment, and other assets and inventories on order that the Secretary transfers to the fund, less the related liabilities and unpaid obligations;

((3)) amounts received from the sale or exchange of property; and

((4)) payments received for loss or damage to property of the fund.

((d)) The fund shall be reimbursed, in advance, from amounts available to the Department or from other sources, for supplies and services at rates that will approximate the expenses of operation, including the accrual of annual leave and the depreciation of equipment. Amounts in the fund, in excess of amounts transferred or appropriated to maintain the fund, shall be deposited in the Treasury as miscellaneous receipts. All assets, liabilities, and prior losses are considered in determining the amount of the excess.