http://sustainablecities.dk/en/city-projects/cases/rio-de-janeiro-the-gondola-opens-up-the-favela
In terms of public transportation, Rio de Janeiro is facing the same problems as many other Latin-American metropolises. The city is served by a comprehensive public transit system, including a modern metro, suburban trains and a large bus fleet. But transportation services are sometimes unable to keep pace with rampant urbanization, especially when it comes to the favelas. These informal settlements are constructed on steep areas where conventional modes of public transportation cannot be considered. As 20% of Rio’s population is living in a favela, a large part of the population has to do without any public transportation.