55 ILCS 5/5-34008
As used in this Division, the term "Expressways" means streets, avenues, roads and drives constituting limited access roadways, with all auxiliary streets, avenues, roads, drives, bridges, viaducts, underpasses, and approaches for ingress and egress to and from the main thoroughfares of such streets, avenues, roads and drives, and other necessary or appropriate appurtenances thereto, to facilitate the movement of through traffic, to be constructed in accordance with the resolutions of the Board of Commissioners heretofore or hereafter approved by the Department of Public Works and Buildings or the Department of Transportation of the State of Illinois and in accordance with the provisions of Section 15d of "An Act to revise the law in relation to roads and bridges", approved June 27, 1913, as amended or Section 5-403 of the "Illinois Highway Code" as the same may from time to time be amended.
55 ILCS 5/5-34008