Thousands of commuters will board the CTA Red Line along the Dan Ryan today for the first time in five months.
Eight stations from Cermak to 95th Street were upgraded as part of a $425-million, five-month reconstruction project.
The trains began running early Sunday morning.
CTA officials say people will notice a much smoother and quicker ride.
All of tracks have been replaced along the entire route.
But Less than 24 hours after re-pening, workers had to perform emergency repairs on a section of the new red line tracks.
A truck cab crashed into a barrier on the Dan Ryan Expressway near 68th Street, and landed on the tracks Sunday night.
The driver was not hurt, but the third rail of the tracks was damaged.
Maintenance workers were able to fix it, and service running on the southbound portion of the tracks is now back open.
The 95th Street station will receive another renovation and upgrade next spring.