Warrants for payments to be made on account of the bonds shall be duly drawn by the state treasurer on vouchers approved by the department.

Moneys required to meet the costs of construction and all expenses and costs incidental to the construction of any particular toll bridge or toll bridges or to meet the costs of operating, maintaining, and repairing the bridge or bridges shall be paid from the proper fund therefor by the state treasurer upon vouchers approved by the department.

All interest received or earned on money deposited in each and every fund provided for in this chapter shall be credited to and become a part of the particular fund upon which the interest accrues.