CHICAGO (CBS) – Attention Brown and Red Line CTA riders: Your commute is about to change in a major way.

And, at least temporarily, it’s going to be slower, confusing and a lot more crowded.

Starting Friday night at 10 p.m., the CTA will suspend Brown Line trains over the Chicago River at Wells Street to allow for reconstruction of the 90-year-old bridge.

This also means fewer trains and different routes during the rush hour.

Riders will have to make alternate plans (see maps below) until early morning on March 11, when regular service will resume during the morning rush hour.

But, the whole thing begins again–between April 26 and May 6. Full service will resume during rush hour on May 6.

The work is being done in two phases as workers focus on one portion of the bridge at a time.

During the day, Brown Line trains will only run between Kimball and the Merchandise Mart. At night, trains will end at Chicago Avenue, to allow workers to make track improvements between Chicago and the Merchandise Mart.

During the morning and evening rush hour only, other Brown Line trains originating at Kimball will switch to the Red Line at Fullerton and run on the Red Line tracks until Roosevelt. (Those trains will run the same way in reverse from Roosevelt to Kimball–again during the rush hour.)

Overall, there will be fewer trains running. That means more crowds and longer commutes.

Separately, there will be Brown Line shuttle trains running around the Loop tracks.

Purple Line Express train service will be suspended.

Details Of Brown Line Changes

(Some Brown Line trains run from Kimball and stop at the Merchandise Mart. During rush hour, others will switch to Red Line tracks at Fullerton and make stops until Roosevelt. Note the brown hash lines along Red Line route. The destination signs on these trains will read “Roosevelt” on a red background. Overnight (after 10 p.m.), trains will stop at Chicago Avenue.)

The CTA will also operate a free shuttle bus service between the Chicago station and the Brown Line trains running in the Loop.

Free Shuttle Bus Route

There also will be bus service available on the No. 37 Sedgwick and No. 37A Sedgwick (rush hour) during the bridge shutdown.

No. 37 Sedgwick Bus Map

No. 37A Sedgwick Bus Map RUSH HOUR

Basically, commuters will have to allow for extra time during the 18-day bridge closure. CTA officials also suggest using buses or the Blue Line if possible.

The CTA says it also will take advantage of the bridge construction to upgrade some tracks in the area around the Merchandise Mart.