LOWELL, Ind. (AP) -

The Indiana and Illinois departments of transportation say they'll ask potential private developers of the Illiana Expressway to submit their qualifications this fall.

The two agencies said Tuesday they've reached an agreement on how to design, build, finance, operate and maintain the proposed 47-mile expressway linking Interstate 65 in northwestern Indiana with I-55 in south suburban Chicago. It includes the upcoming requests seeking information from possible private partners.

The agencies say each state will procure the land for their individual sections of the highway.

The two states say they plan to begin construction in the spring of 2015, but environmental groups have filed a federal lawsuit claiming the Federal Highway Administration didn't adequately assess the project's potential impacts to endangered wildlife, critical habitat and other sensitive areas.