605 ILCS 5/4-509
In addition to other powers of the Department, whenever it is necessary as an incident to the construction of a new State highway or the relocation, reconstruction, extension, widening, straightening, alteration, repair, maintenance or improvement of an existing State highway (including extensions of a new or existing State highway through or into a municipality upon a new or existing street) that property already devoted to a public use be acquired, and the Department and the public agency having jurisdiction over such property have entered into an agreement concerning the acquisition of such property, the Department is authorized to purchase, or to acquire through the exercise of the right of eminent domain, such easements, rights, lands or other property as may be necessary to replace the public property being acquired. The Department is authorized to convey to such public agency such easements, rights, lands or other property it so purchases or acquires for such replacement by deed executed by the Director of the Department.
605 ILCS 5/4-509