The automated train, officially called the Airport Transit System, will operate between 10:30 a.m. and 8:30 p.m. to start. The Chicago Department of Aviation expects to return the train to full, 24/7 operation in early 2022, the agency said Tuesday.

The buses that have shuttled passengers between terminals and to and from parking lots during construction on the train will continue to operate during an overlap period, Aviation spokeswoman Christine Carrino said.

The return of the “people mover” was welcome news to John Link, who was preparing to drive home Tuesday from O’Hare to Dubuque, Iowa, after a trip to Orlando with his wife, two daughters and a daughter’s friend.

The shuttle buses were a “disaster” the first time he took them instead of the train in 2019, but they have become more efficient and drivers are courteous and helpful, he said.

But the train will be even more efficient and cleaner from an emissions standpoint. The cars are roomier and easier to get on and off with luggage and a stroller, he said.

“I’m so looking forward to the train being back,” he said.

When the train reopens, it will include a larger fleet of cars that can run more frequently and an upgraded automatic train control system that will nearly double the number of passengers the system can transport, according to the department of aviation. The track has also been extended so the train connects with the facility that includes rental cars, Pace buses, Metra and parking.

Work to update and expand the train has been going on for more than six years, and the system has been shut down completely since January 2019.

Service interruptions were initially supposed to be kept “to an absolute minimum” during construction, which was to be substantially complete by December 2018, the Tribune found in a 2019 investigation. The project soon devolved into delays, finger-pointing and contract disputes between the city and Parsons Construction Group, the main contractor on the project, the Tribune found.

In recent months, the project contractor said the pandemic contributed to delays, because various manufacturing and travel restrictions made it harder to get parts and for experts to travel to Chicago to help with testing, Carrino has previously said. The contractor also “encountered challenges during the testing phase of the project.”

“We’ve met a number of challenges,” Chicago Department of Aviation Commissioner Jamie Rhee said Tuesday. “This is a very complex project.”

Train vehicles underwent more than 360,000 test miles, or about half a year’s worth of service, said Robert Hoxie, chief development officer for the Chicago Department of Aviation.

“All matters related to safety and reliability are prioritized, and have been addressed by the team,” he said. “Which is why we’re opening the system.”

When the train reopens, it will be able to reach top speeds of 50 mph, according to officials. It should take about 10 minutes to travel from Terminal 1 at one end of the track, to the rental car and transit facility at the other.

The number of train cars will more than double, from 15 under the old system to 36, the agency said.

Vicki Perry, traveling home to the Los Angeles area Tuesday as part of a group of seven family members, said the kids in her group would have enjoyed the train if it had been open.

Instead, they took the shuttle buses on the rainy night they arrived at the airport, water dripping on Perry’s head. That didn’t diminish her impression of O’Hare, though, she said.

“It was one of those things were I was like, this is a gross bus,” she said.

Sherry and Steve Martin, traveling to Schaumburg from York, Pennsylvania, for Steve’s work, didn’t mind the shuttle buses. They love traveling, Sherry said.

But she imagined trains would be more convenient.

Parsons initially signed a $310 million contract for the project, which was later raised to $340 million, Carrino has previously said. The city had agreed to pay more as part of two settlement agreements following disputes between the contractor and the city, and “work that was unforeseen in the originally envisioned project.”

To date, the city has paid Parsons $323.3 million, officials said Tuesday.

The project is funded through a variety of fees, including passenger and car rental fees and general airport revenue bond proceeds.

The airport is undergoing additional expansion and modernization work, including a 16-year runway modernization project. The last runway to undergo work is expected to be in use by December.

An $8.5 billion rehabilitation and expansion, slated to be the largest and most expensive terminal revamp in the airport’s history, is also set to break ground in coming years. It will include a new global terminal and three new concourses.

The airport is also expanding Terminal 5. The expansion is opening in phases, and the terminal will be fully in use by 2023.