A state agency is set to sell $250 million in bonds to help pay for construction of the latest segment of Indiana's Interstate 69 extension. The developer chosen to build the stretch of highway from Bloomington to Martinsville will repay the tax-exempt bonds. The Evansville Courier & Press reports bond documents estimate the total cost of the project at $370 million, with the state paying $80 million up front and making annual payments to I-69 Development Partners to maintain the highway for 35 years. The project will upgrade Indiana 37 to interstate standards. It's part of the I-69 extension that will connect Indianapolis and Evansville. The state is expected to issue the bonds this month. Construction could begin this year, with the section expected to open in 2016.