Brown Line trains will be rerouted into the Red Line subway Friday and through the weekendas crews work to remove slow zones.
Starting at 8 p.m., Brown Line trains between Fullerton and downtown will instead use the State Street subway stations between North/Clybourn and Roosevelt, the CTA said.
Trains will operate as usual between Kimball and Fullerton, the CTA said.
Free shuttle buses will operate between Fullerton and Clark/Lake for any passengers trying to use the Armitage, Sedgwick, Chicago and Merchandise Mart stations.
A shuttle train will also operate around the Loop to connect Brown Line subway service to shuttle buses at Clark/Lake, the CTA said.
The reroute will allow crews to do track work as part of the Ravenswood Connector Rehabilitation Project, which will remove slow zones and improve service.