CTA Blue Line service between Bucktown and the Loop  will be suspended for construction this weekend from 11 p.m. Friday night through 1 a.m. Monday.

The service will be replaced with a substitute bus shuttle. CTA officials said in a press release that the service will also be closed on five other weekends this summer to replace rotting wooden rail ties.

The closures affect track from the Western stop to the Clark and Lake stop.

The old ties, some of which were installed in 1958, are being replaced by new concrete in an effort to eradicate slow zones.

Slow zones throughout the Blue Line typically limit track speed to fifteen miles per hour. The new ties will bring average speeds up to 55 mph, the CTA says.

The Blue Line is running on a single track weeknights through August 31 between Grand and Division after 9 p.m. The authority intends to suspend service on the O'Hare branch of the blue line the weekends of July 20 and August 24, and between the intersection of Western and Milwaukee and Jackson Blvd. the weekend of August 10.  Several more weekend closures will be scheduled for September.