In the event a toll bridge, at the time it is purchased by the Commonwealth under the provisions of §§ 33.2-602 through 33.2-610, is not on the line of a highway then in one of the systems of state highways, the Commissioner of Highways may convey such toll bridge and approaches and other property to such county or counties in which it may be in whole or in part located, upon the payment by such county or counties of the amount paid by the Commonwealth for such toll bridge and approaches and other property, with interest on such amount at six percent per year from the time of such payment by the Commonwealth. The conveyance shall be executed in the name and on behalf of the Commonwealth by the Commissioner of Highways.