Except as otherwise provided in this title, all fees and moneys collected pursuant to the provisions of Chapters 1, 2, 3, 6, 8, 10, 12, and 16 through 26 of this title shall be paid into the state treasury, and warrants for the expenditure of funds necessary for the proper enforcement of this title shall be issued by the Comptroller on certificates of the Commissioner or his representatives, designated by him and bonded, that the parties are entitled thereto, and shall be paid by the State Treasurer out of such funds, not exceeding the amount appropriated in the general appropriation bill. These funds, except as is otherwise provided in this section, shall constitute special funds within the Commonwealth Transportation Fund to be expended (i) under the direction of the Commissioner of Highways for the construction, reconstruction, and maintenance of roads and bridges in the primary state highway system, interstate system, and secondary state highway system and (ii) as authorized by the Commissioner for the expenses incident to the maintenance of the Department, including its customer service centers, and for other expenses incurred in the enforcement of this title. Any funds available for construction or reconstruction under the provisions of this section shall be, as nearly as possible, equitably apportioned by the Commonwealth Transportation Commission among the several construction districts. Beginning July 1, 1998, any balances remaining in these funds at the end of the fiscal year shall be available for use in subsequent years for the purposes set forth in this section, and any interest income on such funds shall accrue to the respective individual special funds. There may be paid out of these funds such sums as may be provided by law for (i) contributions toward the construction, reconstruction, and maintenance of streets in cities or towns and (ii) the operation and maintenance of the Department of Transportation, the Department of Rail and Public Transportation, the Department of Aviation, the Virginia Port Authority, the Department of State Police, and the Department of Motor Vehicles.