The newest line of the STC system, Line 12 (also known as the Golden line) was opened in October 2012.[1][5] It faced issues from the onset of service, with trains on elevated sections forced to reduce speed over worries of derailing.[4] Seventeen months later,[4] the Atlalilco–Tláhuac section, where Tezonco and Olivos stations are located, was closed for twenty months to repair technical and structural faults.[6]