the extensions of Line E and Line H, they now meet Line C at Retiro, where all three terminate. Siemens has modernised the signalling systems on the line, at a cost of $18 million which included the use of Communications-based train control (CBTC) in order to improve the line's frequency and potentially open up the possibility of automatic trains in the future. The work was completed towards the end of 2016. Aside from the signalling system, the line has had its stations refurbished, its rolling stock refurbished and ventilation improved, in part to compensate from the extra heat associated with the air conditioning units added to the trains. Major works took place at Constitución railway station to provide better transfers between the Roca Line, Line C and Metrobus Sur in the area, which includes the construction of a new underground annex to the station. Large segments of track, as well as switches, were replaced. Rolling stock When the line was first opened, it was served by Siemens-Schuckert Orenstein & Koppel rolling stock in its entirety until 2007. In 1999, trains were purchased from the Nagoya Municipal Subway but they ultimately ended up being used on Line D, and were then sent to Line C in 2007 as Line D acquired more new Alstom rolling stock and Line H was opened, meaning that the Siemens O&K trains were needed there as temporary stock until newer Alstom Metropolis trains arrived there. In 2015, refurbished Nagoya Municipal Subway 5000 series rolling stock began to arrive, adding 50% capacity to the line's existing Nagoya trains and reducing journey times. Though the rolling stock was in very good condition and was further refurbished, the purchase was criticised by the Minister of the Interior and Transport, Florencio Randazzo, who accused the Municipal Government of buying dated rolling stock in contrast to the brand new rolling stock purchased by the Ministry for Buenos Aires' commuter rail network and Line A of the underground. Along with the purchase, the existing Nagoya rolling stock was refurbished with air conditioning. Gallery References External links Subterráneos de Buenos Aires (Official Page) Metrovías S.A. Subte Operator (Official Page) Subterráneos de Buenos Aires, C Line System map Buenos Aires Underground Railway lines opened in 1934 Buenos Aires - Line C 1934 establishments in Argentina