In March 2014, a tender for construction of the central section of the line was announced. The section is long and includes 7 stations, two of them transfer to lines 1 and 2. With the announcement of the tender, it became clear that the initial plans for 19 stations had been partly amended and 2 of the stations, one at Doyran boulevard and another at Shipka street, will be not be built. The tunnel of the central section shall be excavated by a tunnel boring machine, while the construction of stations shall be awarded to other companies. The construction of the section shall be completed within 45 months. In January 2015, a tender for 20 trains that shall serve the central section of the line was announced. Driverless train operation, with Grade of Automation 3 (GoA 3), and platform screen doors will ensure the safety of the passengers. Unlike Lines 1 and 2, where the trains collect power through a third rail, Line 3 trains will be equipped with pantographs. CAF and Siemens applied bids in the tender for the trains, with Siemens winning it.