This linear design leaves much of the area inside the arc—and the millions of people who live there and in the hinterlands beyond—with little access to rapid transit.

The city has tried to address the lack of metro access in this part of the city by building out a network of bus rapid transit lines. Spurred by Brazil’s hosting of the 2014 World Cup and with an eye towards the 2016 Olympics, four BRT lines were planned to connect various sports facilities in the city, and to connect with the metro, suburban rail lines, and the airport. The first BRT line began operations in 2012, but the roll out was slow and only part of two lines were operating during the World Cup. The Transolimpica BRT line connecting to Barra da Tijuca, the third of the system to be realized, will only have three of its stations in operation during the Olympics.

Capanema Alvares says the city has not provided enough options for its transit-dependent low-income population. “They put in two very, very different means of transportation. One for the rich, one for the poor,” she says. “We’re calling it transportation apartheid.”

"Line 4 is not going to benefit the city, because it's all about selling the city," says Capanema Alvares, pointing to Carlos Carvalho, the billionaire developer who's planning to turn the athletes village and Olympic park into a wealthy enclave called Ilha Pura, or Pure Island, after the Olympics. "The metro line is just real estate speculation."

But some are still hopeful the system can be improved to better meet the needs of the entire city. Licinio Machado Rogério is one of the co-authors of the “Manifesto for a Better Route for the Rio Metro Line 4,” written in 2010 with the support of 30 neighborhood organizations. It called for the state government to cancel its plans for extending the linear path of the pre-existing subway lines and re-route the line into the center of the city, creating more of a mesh of interlinked subway lines. Rogério says this was the original design for Line 4 when it was first planned in the late 1990s. Though the straight line approach was built, he says it’s not too late to alter the system. Line 1, he says, should be extended into a ring, and Line 4 should cross through that ring into the center of the city like a no-smoking sign. At its other end, Line 4 should be extended further west to better link with the BRT system.

“Every place we make a line of the metro will be better for the population,” he says. “Line 4 is necessary, but it’s not the priority. We have other lines that are more necessary.”

For now, Line 4 will function as an extension of the system, stretching out to the wealthy western suburbs. But even the route that was built falls short; Line 4’s terminus in Barra da Tijuca is still eight miles away from the Olympic Park and athletes’ village. Shuttles and BRT will bridge the gap between the new subway line and the Olympic events it was built to serve.

This post appears courtesy of CityLab.

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Nate Berg is a freelance reporter and a former staff writer for CityLab. He lives in Los Angeles. Connect Twitter