Unidad de Gestión Operativa Mitre Sarmiento

Trenes de Buenos Aires, a company formed in 1995 to take over rail concessions granted by the Argentine government, as part of railway privatisation during the presidency of Carlos Menem, operated commuter rail services over Sarmiento and Mitre lines in Buenos Aires which had previously been run by state-owned companies since nationalisation of the railways in 1948. In spite of the large state subsidies received by the company a serious decline in the standard of its services, and fatal accidents (especially, the 2012 Buenos Aires rail disaster), led to the concession for both lines being revoked in 2012 through Decree N° 793/12, and to these services being taken over by the newly formed UGOMS.

In September 2013, Minister of Transport of Argentina, Florencio Randazzo, announced that Mitre and Sarmiento lines would be temporarily taken over by state organism SOFSE. SOFSE operated both lines until 12 February 2014, when they were given under concession to Corredores Ferroviarios. As a result, UGOMS and Unidad de Gestión Operativa Ferroviaria de Emergencia were dissolved. However both lines are now again operated by SOFSE following the renationalisation of the railways in Argentina.