The Controller shall, from time to time, determine whether any portion of the money or investment in the Department of Motor Vehicles Uncleared Collections Account in the Special Deposit Fund is not necessary for immediate use and, if so, the amount thereof shall thereupon be designated as “available money.” On demand of the Department of Transportation from time to time, the amounts demanded, not exceeding ten million dollars ($10,000,000) in the aggregate, shall, on order of the Controller, be transferred to the State Highway Account from the “available money” and shall be available for the acquisition of properties to constitute rights-of-way for state highway purposes. On demand of the Controller, the money shall be retransferred to the Department of Motor Vehicles Uncleared Collections Account.