The Illinois Department of Transportation maintains a website called http://www.gettingaroundillinois.com/ According to the site,
Getting Around Illinois is a web-based interactive mapping site that provides the ability to search and display several sources of transportation data. You can find information on winter road conditions, average annual daily traffic, road construction, trucking routes, and planned road projects.
From that main page, you can get current winter road conditions at http://wrc.gettingaroundillinois.com/pages/wrc.htm. I have found this site to be very valuable for making travel plans during or after a winter storm in Illinois.
Have you ever noticed the weather instruments alongside Interstate Highways? Those systems are called Road Weather Information Systems, or RWIS for short. They include weather sensors as well as roadway sensors to measure pavement temperatures and detect wet or icy conditions. Here is the link for the RWIS data in Illinois: http://www.gettingaroundillinois.com/mapviewer.aspx?mt=rwis