Line B (Buenos Aires Underground)

Line B of the Buenos Aires Underground runs 11.75 kilometres (7.30 mi) 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 4 ft 8+1⁄2 in (1,435 mm) 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 6000 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 have been partially supplanted by CAF 6000 rolling stock, acquired in 2013 from the Madrid Metro.