The secretary is hereby authorized and empowered to use the proceeds of any bonds herein authorized, together with any other available funds, for paying the costs relating to construction, reconstruction, maintenance and improvement of highways in this state and expenses incidental thereto and for paying expenses of authorizing and issuing the bonds, for paying the interest on the bonds until revenues therefor are available in sufficient amounts, for purchasing bond insurance and other credit enhancements on the bonds, and for funding such reserves as the secretary deems necessary and desirable.