of underground, grade-level, and elevated railway elements. It may be extended south to better serve commuters to and from Chalkidiki. The western loop will be extended with three branches, adding four stations. Detailed planning of the eastern extension to the airport is set to begin in March 2019 and be finished in time for the project to be financed as part of the 20212027 funding cycle of the European Regional Development Fund. This happened on 18 March. The proposed route starts at the airport and follows Greek National Road 67 before joining Greek National Road 16 and then connecting with station and the rest of Line 2. Operations Stations, depot and rolling stock All 18 stations currently under construction were designed with platform screen doors for maximum protection, while the trains will be driverless. Eighteen Hitachi Rail Italy Driverless Metro units will be in service on Line 1, and 15 on Line 2. The articulated, four-car trains will be long. They will have seating for 96 passengers and standing room for 370 more. The trains will use 750 V DC third rail electrification, while tracks have been laid to the standard gauge of . A carriage was on display at the September 2018 Thessaloniki International Fair before trial runs in 2019. As of August 2019 two complete train sets have been delivered to the depot, with an additional train set expected every 2 to 3 months. The system's level of automation has prompted Attiko Metro to call it "the most modern metro in Europe". A depot is under construction with the intention of serving both lines, with a total built-up area of and a total cost of €130.5 million ($ million). Apart from being the system's automated remote control command centre, the complex will also house the offices of Attiko Metro, the Thessaloniki Transport Authority (TheTA), and the Thessaloniki Metro operating company, as well as railway stock maintenance facilities, two restaurants, and a crèche. It is expected that the development of the depot will attract investment to the area, and there have been calls to make provisions for a passenger station at the depot. The depot complex is expected to be finished in May 2019. Fares and park and ride As part of the initial design, 3,700 park and ride parking spaces were created – 1,050 spaces at , 650 spaces , and a further 2,000 at , the system's