Trenes de Buenos Aires operated the Mitre and Sarmiento lines until the concession was revoked after the Once rail disaster on February 22, 2012, at Once Station, Buenos Aires, in which 51 people died and at least 703 people were injured, TBA was placed under federal intervention on February 28; its concessions to operate the Mitre and Sarmiento lines were ultimately revoked on May 24. After the cancellation of the contact, both lines were taken over by transitional consortium Unidad de Gestión Operativa Mitre Sarmiento (UGOMS). Metrovías took over the operation of the Buenos Aires Subte, the Buenos Aires Premetro, and the Urquiza Line in 1994, and established an earlier closing time of 23:00 on all three systems in order to conduct extensive maintenance and reconstruction, which was retained even after the reconstruction was completed. Numerous proposals to extend the operating hours of all three Metrovías-operated services have failed.