CHICAGO (AP) — New, modernized rail cars have made their debut on Chicago's Red Line.

The Chicago Transit Authority added two eight-car trains to the line on Monday. Transit officials say they'll continue to add more trains until eventually the entire Red Line fleet is replaced. The 5000-series rail cars previously had successful debuts on the CTA's Pink Line and Green Line. They're part of a nearly $1.2 billion CTA effort to add more than 700 cars.

The new cars will replace 35-year-old rail cars on the Red Line. The CTA says the cars have smoother acceleration and braking, aisle-facing seating to add room and LED displays.