The concept of a modern, high-capacity bus system is often called bus rapid transit. BRT differs from conventional bus operations in that the coaches—often newer, more comfortable vehicles—run on dedicated portions of roadways, and stations feature off-vehicle fare collection and slightly elevated platforms to speed up boarding. Proponents say BRT systems have lower construction costs, can be built in a quarter to half the time subways require, and their operating costs are almost always covered by fare collection, eliminating the need for subsidies. BRT also offers more flexibility, because routes can be adjusted as the city grows, different bus types can be deployed, and cars can be allowed to use bus lanes during weekends.

Illustration: Bryan Christie Design

Now, there’s some debate about how many people BRT—or other systems, for that matter—can transport. One way transportation experts assess a system is by measuring its maximum throughput—much as a mechanical engineer would gauge the flow of water through a pipe. In that way, a single-lane BRT line is said to transport up to 15 000 passengers per hour in one direction, or nearly seven times as many as a freeway car lane. BRT’s capacity is similar to light rail’s but smaller than that of subway systems, some of which carry more than 50 000 passengers per hour. Although it would be nice if every metropolis had ample subway service, building such infrastructure is often beyond a city’s means. Whereas construction costs for a light-rail line can run anywhere from $15 million to $25 million per kilometer and subway systems from $50 million to $200 million, BRT systems require from less than $1 million to $20 million.

Not all bus corridors in São Paulo are full-featured BRT systems. Indeed, it’s hard to characterize all of this city’s different busways. You can find here nearly all the different configurations a transportation planner could concoct. Segregated corridors in the middle of avenues? A handful. Dedicated bus lanes on the left of roadways? Four, built not long ago. São Paulo is even constructing a 20-meter-high elevated busway that snakes its way above traffic—a controversial project whose original design called for all-electric, computer-controlled buses but which will go into operation using diesel coaches with drivers at the wheels. (One critic called it a “drunken roller coaster that escaped from Playcenter [the local amusement park].”)

During the past decade, São Paulo reorganized its maze of bus lines into a more efficient network: structural lines with high-capacity coaches running mostly radially toward the city’s center, and local lines with nimbler microbuses connecting neighborhood streets to other bus lines and subway and train stations. São Paulo’s 11 bus corridors became a key piece in this reorganization. Its two most successful, the 14-km-long Santo Amaro–Nove de Julho corridor and the 33-km-long São Mateus–Jabaquara corridor, each transport more than 200 000 passengers per day.

“São Paulo is the biggest laboratory in the world in terms of transportation in many ways,” says Darío Hidalgo, a transportation specialist with the global management consultancy Booz Allen Hamilton, in Bogotá, Colombia. He says that bus experiments in São Paulo and in another Brazilian city—Curitiba, which began constructing a pioneer BRT system more than 30 years ago—helped inspire other cities to develop their own rapid bus projects. Bogotá, with nearly 7 million people, chaotic traffic, and not a single subway line, completed in 2000 what many consider to be an exemplary BRT project: the 80-km-plus TransMilenio system, which can move 40 000 people per hour per direction using two lanes. “It’s a world record for buses,” says Hidalgo, who participated in the project.

Other cities that have built or are planning BRT systems include Boston, Cape Town, Chicago, Los Angeles, Mexico City, New Delhi, New York City, Ottawa, Paris, and Sydney. There are already 15 BRT systems operating in Asia—including those in Beijing, Jakarta, Nagoya, and Seoul—and 24 others soon to come. All these BRT systems may be very different in their design and operation, but they attempt to accomplish the same goals. One is getting people to use public transportation over private automobiles, thereby improving traffic and reducing tailpipe emissions. The other is providing a better way of getting around for those who don’t own cars. In most cities in the developing world, the carless are the majority of the population (70 percent in São Paulo, for example), so implementing an efficient bus system is also a matter of social equity.

How do planners in a megacity like São Paulo go about designing its transportation system? How do they know, say, where to build new busways?

Many of the answers come from a conference room—nicknamed the “situation room”—at the headquarters of São Paulo’s metropolitan transportation agency. Indeed, improving transportation in São Paulo has been quite a war.

Use of public transportation had been declining for decades, but now for the first time its share is smaller than that of private transportation: 47 ­percent versus 53 percent, according to the last major ­government-­sponsored survey. With more cars on the street, driving has only gotten worse. Rush-hour backups throughout the city routinely add up to more than 100 km. And every three minutes, an additional automobile joins the fray. Lined up bumper-to-bumper, all of São Paulo’s 5.5 million cars would form a queue some 20 000 km long, enough to go halfway around the world. It’s probably a good thing people don’t start out at the same time.