Line B of the Buenos Aires Underground runs from Leandro N. Alem to Juan Manuel de Rosas in Villa Urquiza. Line B opened to the public on 17 October 1930. In recent years, it has held the title of being the most used line of the Buenos Aires Underground, and its patronage has increased even more after the opening of a section of tunnel between Los Incas station in the neighbourhood of Parque Chas and a shopping centre in Villa Urquiza. It was the first line in Buenos Aires whose stations had turnstiles and moving stairways. It is the only line that uses third rail current collection, while the rest of the Underground lines collect electric current from overhead lines, although there has been ongoing conversion to overhead lines to incorporate new rolling stock. Its gauge of is the same as the rest of the Buenos Aires underground system. The rolling stock currently used on the B line are former Tokyo Metro (formerly Eidan Subway) 300/500/900 stock, which was used on Marunouchi Line, and CAF 5000 stock. The Japanese units were acquired in the early 1990s, and offer less sitting room than the previous rolling stock, increasing the line's capacity during peak hours. The Japanese trains are being phased out and replaced by newer CAF 5000 and CAF 6000 rolling stock acquired from the Madrid Metro. History In 1912 the Congress of Argentina enacted Law 8,870 to construct a line that would unite the Correo Central (Central Post Office) and the intersection of Triunvirato and Elcano streets, and meet with the tracks of the Buenos Aires Central Railroad (Ferrocarril Central de Buenos Aires or FCCBA), which belonged to the same business group, through an 8.7 km tunnel. The Act provided that the works "would help reduce traffic in the central area of the city". On 17 December 1927 in New York City the financial agreement to build the line was signed between Teófilo Lacroze, the president of Banco de la Nación Dr. Tomás de Estrada, Dr. Louis J. Rocca directory owner of Ferrocarril Terminal de Buenos Aires and bankers Harris and Forbes. This agreement granted the concession of the line for passengers, parcels and freight to Lacroze Brothers Company. The construction was carried out by the Argentine builder Dwight P. Robinson & Cía, and the line was called Ferrocarril Terminal Central de Buenos Aires (Buenos Aires Central Terminal Railroad). The