The Department may issue, in the name of the State, revenue bonds of the State, payable solely from the revenues of the Department, for the purpose of paying the cost of construction (including interest during the period of construction and for 1 year thereafter) of any toll crossing which it may construct under this chapter or to defray the cost of constructing or improving highways, and for the purpose of refunding any bonds issued under this chapter, at or prior to the maturity thereof.