When it comes to moving lots of people on buses, transportation experts are quick to mention one particular project these days: the Transmilenio.

The Transmilenio, in Bogotá, Colombia’s capital, is a bus rapid transit (BRT) system with an 80-kilometer-plus network of lines that transports about 1.2 million passengers per day. The system relies on high-capacity articulated coaches, and to speed up boarding its stations feature elevated platforms and off-vehicle fare payment—much as in a subway.

In fact, Bogotá had tried for decades to initiate the construction of a subway system, but attempts failed because of the high costs involved and unfavorable political conditions. In 1997 Bogotá’s mayor, Enrique Peñalosa, proposed a bus-based mass transit system modeled on those in operation in the Brazilian cities of São Paulo and Curitiba. The Transmilenio project was born.

Peñalosa envisioned the new bus system as more than a transportation project—he saw it as a key piece of a broader urban development plan that strongly championed public transportation over private automobiles. The Transmilenio began operation in late 2000. It didn’t help much with the city’s congestion problems, but it is now regarded by public transportation experts worldwide as a highly successful mass transit project.

To learn more about Bogotá’s system, IEEE Spectrum Associate Editor Erico Guizzo talked to Colombian engineer Darío Hidalgo, who was the deputy general manager of the Transmilenio mass transit authority from June 2000 to September 2003. He’s now a transportation consultant with Booz Allen Hamilton and has recently participated in BRT projects in Chile, Nigeria, Tanzania, and Thailand.

IEEE Spectrum: How does the Transmilenio system differ from conventional bus operations?

Darío Hidalgo: It brings all things that you can put together for a BRT in a single place. It has segregation for the buses and real bus stations—not just bus stops—with level boarding and prepayment, and passengers go into the bus through many doors, like in a metro. So the boarding time is very short, and this increases overall performance a lot. There’s also local and express service, so some buses don’t stop at every station. This gives a very high capacity to the system, not observed in other systems yet. At peak load periods, capacity has been observed to be over 40 000 passengers per hour per direction. It’s a world record for buses.

Spectrum: What kind of technologies does the Transmilenio use?

Darío Hidalgo: There are several. For fare collection it uses equipment such as contactless cards and all the supporting technology for transactions. There are information systems for the user, like real-time displays at bus stops or stations, showing what time the buses are coming, for example. And then there’s the management of the bus operations, which relies on a centralized control with automatic vehicle location. Vehicles run with very short headways, like less than 3 minutes between buses. You just can’t wait until the vehicle reaches a terminal to know if it’s on time or not—you need to know it all the way through its route. That way you’ll be able to make adjustments and keep the system with the right frequency. Also, in case of contingencies, if an accident happens—and they do happen—you’re able to put the emergency services in place and restore the operation. Without centralized control and related technologies, these types of things would be very difficult, if not impossible.

Spectrum: And what about modeling and simulation—is it important?

Darío Hidalgo: It’s very important. Knowing your numbers before implementation can be key to the success of the system. In terms of modeling the transport of passengers, this is an area where research has reached a mature level. The tools are very advanced, although there could be better ones for public transportation projects. In complex systems like the Transmilenio, simulation may be the only way to go in terms of learning how to solve the bottlenecks and improve operations. You don’t want to try certain changes in real life because you could create serious trouble.

Spectrum: How does the Bogotá bus system compare with that of, say, São Paulo?

Darío Hidalgo: São Paulo is bigger than Bogotá and has more population density, so the challenges are, in general, bigger there. Also, the industry and the planning practices and bus industry in Brazil are more developed. And in Brazil you have companies that own the bus fleets and run the business very formally. In Bogotá, many vehicles are individually owned or affiliated with companies that really don’t operate as companies but as intermediaries. So Bogotá is implementing the Brazilian experience in a very different context. The results are very good so far, but we still have a long way to go. The Transmilenio moves 1.2 million passengers per day, and that’s only 20 percent of the transit trips in the city; the other 80 percent are still very disorganized. So the city is working to integrate and improve the traditional bus system and expand the Transmilenio.

Spectrum: Why should cities consider bus rapid transit?

Darío Hidalgo: BRT systems can be implemented at one-fifth or one-tenth of the cost of a comparable rail system, light rail, or metro. In terms of implementation time, it would be one-half to one-quarter. That’s why it became so popular in Latin America, where public transportation ridership is very high. It’s 70 percent of all trips in Bogotá, for example. The situation is different in other places, like U.S. cities, where public transportation accounts for only 3 to 4 percent of total trips in urban areas. So while the challenge in Latin America is to provide better service to those people who are already in public transportation to prevent them from moving to less efficient modes, the challenge in U.S. cities is to bring the people who use automobiles to switch to public transportation. Those are different types of challenges, and so in the United States you need to invest much more to make BRT very attractive than we do here in Latin America.

Spectrum: What will be the role of BRT in the future of megacities?

Darío Hidalgo: BRT is not a silver bullet, and there are ways that rail systems may outperform bus systems, like in environmental performance and reliability. BRT should be part of the transport system, along with metro and rail, especially where it’d be more cost-efficient than the other systems. I have to say, the BRT elements have been already known by practitioners for many years. What’s new is the systematic combination. A simple thing like segregating general traffic from buses has been applied for many years. But now you not only separate the buses and the general traffic, but you also put elevated boarding stations, automatic off-vehicle fare collection, and you combine local and express type of services. That’s what makes a high level BRT. So what’s new is the packaging.

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