Ongoing extension/modernization of the ATS requires its complete shutdown until early 2020. Shuttle buses provide service when the ATS is not running. The ATS/shuttle bus service is free and connects the terminals to parking and rental lots. The entire system uses platform screen doors, which means that all the stations are enclosed with doors along the boarding area. When the train arrives at a station, the doors of the train and the station align and open in sync with each other. This method prevents people from leaving the platform, falling on the tracks or tampering with restricted areas. Climate control is also ensured since the four terminal stations are directly connected to the airport. Trains are operated with either two or three cars depending on the expected load, and each car can hold 57 passengers, most of them standing, and 8 seated.
Stations
When available, ATS stations are fully accessible, and provide access to the elevated ATS tracks. The system has two tracks, and each train stops at all five stations traveling in both directions. Its west end is at Terminal 1, at the west end of the terminal core, and makes a counterclockwise loop around the parking garage, with stops at Terminal 2 and Terminal 3. Parking Garage A is accessible from any of the three terminal stations, as is the O'Hare terminal of the CTA's Blue Line. Parking Lots B and C are only accessible from Terminal 1 and 3 stations, respectively. Outside the terminal loop, the ATS travels east to Terminal 5, currently the airport's international terminal. It then turns north, crosses over the main access road and Blue Line, and reaches Parking Lot E. The station also features a Pacebus stop and a "Kiss 'n' Fly" drop-off area. A shuttle bus also connects this station with the O'Hare Transfer station on the North Central Service, providing Metra service to Union Station inbound and Antioch outbound during service hours.
Fleet
The ATS uses the French-based VAL technology, which features fully automated, rubber-tiredpeople mover cars. The system is capable of traveling at speeds of up to, and is the only remaining site using the VAL 256-type vehicle, named for its width of. The 15 Matra vehicles are being replaced by 36 new Bombardier Innovia APM 256 vehicles.
Modernization and extension
As part of a larger, $782 million project involving a new integrated transit center, the ATS is undergoing a $310 million modernization and expansion that includes replacing the existing 15-car fleet with 36 new Bombardier vehicles, upgrading the previous infrastructure, and extending the line 2,000 ft to the new Multi-Modal Facility on the east side of Mannheim Road. The ATS normally operates 24 hours a day, seven days a week, but the rehabilitation requires the complete shutdown of the ATS until early 2020. Free shuttle buses provide service when the ATS is not running. The new Multi-Modal Facility is the home of all on-airport rental car firms as well as connections to Metra at the O'Hare Transfer station. The ATS closed on January 8, 2019 for modernization work and will reopen in 2020. As of July 31, 2020, it had not yet reopened. As of May 2019, the original rolling stock is being stored on a lot on Taft Rd next to the intersection with Irving Park Rd near the airport.
