Pink Line service will not operate in the Loop and will stop at Ashland.
In addition, the Red Line subway is closed, meaning all trains are using the elevated tracks between Fullerton and Cermak-Chinatown. Trains will also use the elevated tracks along Wells and Van Buren in the Loop.
Work has also impacted the CTA Blue Line.
Operations were expected to return to normal by early Monday morning.
For more information on CTA service changes, log on to http://www.transitchicago.com/news/whatsnewA.wu?action=displaynewspostingdetail&articleid=116838.