When one considers that São Paulo is the largest city in Brazil, South America, and the entire Southern Hemisphere, as well as the 12th largest city in the world as measured by population (11 million within the city limits, 20 million in the metropolitan region), the public transit network is quite small for a megalopolis of this size. The São Paulo Metro opened in 1974 after six years of construction. As of 2015, it consists of five traditional Metro lines and one monorail line, with several extensions under construction and in the planning stages. Including the monorail, the system has 46.5 miles of track and 66 stations with a daily ridership of 4.6 million passengers. Service is very frequent at all times of day due to the high volume of passengers. Line 4 is being built and operated under a private-public partnership with a company called ViaQuatro as opposed to being built and operated directly by Companhia do Metropolitano
de São Paulo.
In addition to the Metro, a commuter rail network called Companhia Paulista de Trens Metropolitanos (CPTM) also operates in the São Paulo region. It has six lines along 160 miles of track, serving 2 million passengers daily. There are numerous transfer points between CPTM and the Metro.
São Paulo has an extensive bus network with over 16,000 buses, 290 of which are trolleybuses. Most bus routes are operated under contract to SPTrans, which oversees the entire network. However, some bus routes are operated and managed by Empresa Metropolitana de Transportes Urbanos de São Paulo, (EMTU). São Paulo has a bus rapid transit network, currently known as Expresso Tiradentes, since the mid-1990s. It opened in 2007 after many years of delays and currently operates on two segments.
The original Sao Paulo Metro stock was built by Budd in preparation for the initial segment opening in 1974. Since then, additional rolling stock has been manufactured by Mafersa, CAF, Alstom, Siemens, and Bombardier. As of 2015, the oldest trains, known as A stock, are being modernized and redesignated as J stock.