That's because three new rail bridges will have replaced the crumbling structures at Grove, Dempster and Greenleaf Streets.
They were more than 100 years old.
The work cost more than $10 million.
Because of advances in technology, workers were able to assemble the 400,000 pound structures on site and roll them into place.
That enabled the work on each structure to be done over a long weekend.
"This is one of the few places where trains had to roll to a stop in many instances so it is part of our ongoing effort to eradicate slow zones throughout the CTA system," said CTA president Forrest Claypool.
The work is scheduled to be completed between 8:30 friday night and 4 a.m. Monday morning.
