Upon application in writing by the Commissioner of Transportation, the Comptroller may authorize the temporary use by the commissioner of any unexpended balance or part thereof of any specific appropriation or any other funds applied without any specific appropriation for or to be used by the Department of Transportation, and such use may be for any purpose for which the commissioner is authorized to expend any money of the state, provided, in case of any funds received from the federal government under the provisions of any act of the Congress providing for federal aid to states for highways, or from towns or railway companies under statutory provisions concerning the construction of bridges on state highways, the amount of such unexpended balance so transferred shall be carried to the credit of the specific appropriation from which such funds have been taken or transferred.