TransMilenio

Based on Wikipedia: TransMilenio

In 1998, if you wanted to travel thirty kilometers across Bogotá by public transit, you'd better pack a lunch. The journey would take two hours and fifteen minutes, bouncing between thousands of independently operated minibuses that shared no schedules, no coordination, and no particular concern for getting you anywhere efficiently.

Ten years later, that same trip took fifty-five minutes.

What happened in between is one of the most dramatic urban transportation transformations in modern history—a story involving a maverick mayor who cancelled a subway system, a fleet of cherry-red articulated buses, protests that devolved into riots, and a system that would eventually inspire cities from Mexico to Chile to rethink how they move people.

The Mayor Who Chose Buses Over Trains

When Enrique Peñalosa was elected mayor of Bogotá in the late 1990s, he inherited two grand plans. The first was a network of elevated highways that would slice through the city. The second was a subway system, following the model that Medellín, Colombia's second-largest city, had built several years earlier.

Peñalosa cancelled both.

This was not a popular decision at the time. Subways carry a certain prestige. They feel permanent, modern, first-world. Buses, by contrast, feel like what you build when you can't afford the real thing. But Peñalosa had crunched the numbers, and the numbers told a different story.

Bus Rapid Transit—known by the acronym BRT—could move nearly as many people as a subway at a fraction of the cost. The key insight was deceptively simple: the problem with buses isn't buses. The problem is that buses get stuck in the same traffic as everyone else. Give them their own dedicated lanes, their own elevated platforms, their own signal systems, and suddenly you have something that functions much like a subway—but running on rubber tires instead of steel rails.

The system that emerged from this insight was called TransMilenio, and it opened to the public in December 2000, just three years after the project began. By comparison, subway projects routinely take a decade or more from conception to completion.

How It Actually Works

TransMilenio operates on a remarkably elegant principle. Down the center of major avenues—called "troncales" in Spanish—four lanes are dedicated exclusively to buses. No cars, no motorcycles, no delivery trucks. Just buses.

The stations sit in the middle of these avenues, raised above street level. Passengers reach them by walking across pedestrian bridges that span the regular traffic lanes. This might sound inconvenient, but it solves a critical problem: the buses never have to pull over to the curb and merge back into traffic. They stay in their dedicated lanes, stopping only at platforms designed specifically for them.

The outer two bus lanes allow express services to bypass buses stopped at stations. This means that while a local bus is picking up passengers, express buses can continue past at full speed. It's the same principle that makes express trains in subway systems so effective—except achieved with paint and concrete rather than separate tunnels.

The buses themselves are articulated, meaning they bend in the middle like an accordion. This allows them to carry up to 160 passengers each. In 2007, the system introduced bi-articulated buses—essentially buses with two accordion joints instead of one—that can carry 270 passengers. These vehicles are longer than most city buses and approach the capacity of some light rail systems.

The station platforms are built to the exact height of the bus floors. When a bus arrives, its doors and the station doors open simultaneously. Passengers walk straight across, no steps required. This level boarding dramatically speeds up the loading process and makes the system accessible to wheelchair users and people with mobility limitations—at least on the main trunk lines.

The Numbers That Changed Everything

The initial construction cost for the first forty-one kilometers of TransMilenio routes was approximately 240 million US dollars, or about 5.85 million dollars per kilometer.

To put this in perspective: subway construction in Latin America typically costs between 100 and 200 million dollars per kilometer. In North America and Europe, the figures are often several times higher. The Second Avenue Subway extension in New York City, which opened in 2017, cost roughly 2.5 billion dollars per kilometer.

TransMilenio cost less than half a percent of that figure.

The Colombian national government provided about seventy percent of the funding, with the city of Bogotá contributing the remaining thirty percent. A special company was created to build and manage the central system, while private bus companies were awarded contracts through competitive bidding. These contractors are paid based on the total kilometers their vehicles operate—an incentive structure that encourages keeping buses running and on schedule.

Daily ridership reached 800,000 within months of opening. By 2006, it had grown to over a million. By 2018, the system was carrying 2.4 million passengers on an average weekday. Today, TransMilenio consists of twelve corridors containing 120 bus routes that stretch across 114 kilometers of dedicated busways.

The Feeder System

A transit system is only as good as its ability to get people to the stations. TransMilenio addresses this with a network of feeder buses—called "alimentadores" in Spanish—that fan out from major stations into neighborhoods that the main trunk lines don't reach.

These feeders are smaller, regular buses painted green or blue rather than the signature TransMilenio red. They operate without dedicated lanes, mixing with regular traffic on neighborhood streets. Critically, there's no additional fare to use them. Pay once to enter the system, and you can transfer to feeders for free.

As of 2024, nearly 900 feeder buses supplement the 1,800 buses running on the main trunk lines. Together, they form an integrated network that reaches deep into Bogotá's sprawling neighborhoods.

The system also accommodates cyclists. Twenty-seven bicycle parking facilities at major stations provide over 7,300 parking spaces. This multimodal approach—combining bikes, feeder buses, and trunk line buses—gives residents flexibility in how they complete their journeys.

Recognition and Replication

In 2005, Bogotá won the first-ever Sustainable Transport Award, recognized for TransMilenio and the city's broader urban cycling strategy. The city won the same award again in 2022, in part because it had assembled a fleet of 1,485 electric buses—one of the three largest electric bus fleets outside of China.

Eight of TransMilenio's corridors have been certified under the BRT Standard, an international rating system that evaluates bus rapid transit quality. Two corridors—Autonorte and Caracas—received silver certification. Five others—Americas, Calle 80, Eldorado, NQS, and Suba—achieved gold.

More significantly, the TransMilenio model has spread across the world. Mexico City launched its Metrobús system following Bogotá's example. Santiago, Chile restructured its entire public transit network around similar principles (though that system, initially called Transantiago, faced significant implementation challenges). Cities across Asia, Africa, and even some in North America have studied TransMilenio as they design their own rapid transit solutions.

The System's Darker Side

For all its achievements, TransMilenio has never been universally loved. In 2016, the system had an 86 percent disapproval rating from users.

Eighty-six percent.

The complaints are numerous and serious. The most visceral is overcrowding. During rush hours, the system averages eight passengers per square meter. To visualize this: imagine a space roughly the size of a closet, and then imagine cramming eight adult humans into it. Now imagine trying to breathe while the bus lurches through traffic.

Stations become so packed during peak times that passengers physically cannot exit the buses when they reach their stops. Lines to add credit to the smart cards used for payment can stretch so long that commuters miss multiple buses while waiting. The experience of using TransMilenio during rush hour is, by many accounts, genuinely miserable.

The crowding creates secondary problems. In such close quarters, pickpocketing thrives. Official data from 2017 recorded 3,404 thefts in TransMilenio stations and another 1,442 on the buses themselves.

More disturbing are the rates of sexual assault. A 2012 survey conducted by Bogotá's Secretary for Women's Issues found that 64 percent of women reported experiencing sexual assault while using TransMilenio services. The crowding makes it easy for attackers to target women and escape notice. The city has tried various countermeasures—women-only buses, undercover policewomen—but reports of assaults continued through at least 2018.

Protests and Riots

Bogotá's relationship with TransMilenio has occasionally turned violent.

In May 2006, bus drivers not associated with the TransMilenio system launched a two-day strike. They objected to the compensation offered for scrapping their old buses, some of which were over twenty years old. They also protested new environmental restrictions that limited when older, more polluting buses could operate. The strike disrupted the city but remained relatively peaceful.

The events of March 9, 2012 were not peaceful.

Hundreds of protesters, many of them students, took to the streets over TransMilenio's deficiencies—the high prices relative to service quality, the severe overcrowding, the chronic delays. The protest escalated into looting and vandalism. Windows were smashed. Several of Bogotá's main roads were blocked. Eleven people were injured. Damage exceeded half a million dollars.

Riot police responded with tear gas and water cannons. Vandals were detained. The immediate crisis passed. But the underlying frustrations that drove people into the streets remained.

User strikes have erupted periodically since then, with protesters blocking bus lanes and occasionally halting the entire system. These demonstrations sometimes devolve into riots requiring heavy police presence and crowd control measures. The pattern speaks to a fundamental tension: TransMilenio is simultaneously indispensable to millions of commuters and deeply resented by many of them.

Environmental Complications

TransMilenio was conceived partly as an environmental solution—a way to reduce the air pollution caused by thousands of aging, uncoordinated minibuses spewing exhaust across the city. The irony is that the system itself has become a significant pollution source.

A 2015 study by the National University of Colombia found that seventy percent of air pollution near TransMilenio stations was caused by buses from the first phase of the system's rollout. More than half of the first and second phase buses were violating atmospheric emissions rules. Many of these vehicles ran on diesel fuel, and diesel exhaust has been classified as carcinogenic to humans by the World Health Organization.

The city has worked to address this. In late 2018, TransMilenio ordered 1,383 new buses to replace aging vehicles. About half were powered by compressed natural gas and achieved Euro 6 emissions standards—among the strictest in the world. The other half were diesel but met Euro 5 standards, still a significant improvement over the original fleet.

More dramatically, the fleet of 1,485 electric buses announced by 2022 represents a genuine shift toward zero-emission operation. Whether these cleaner vehicles will be sufficient to rehabilitate TransMilenio's environmental reputation remains to be seen.

Infrastructure That Crumbles

Buses may be cheaper than trains, but the infrastructure they run on still requires serious engineering. TransMilenio's dedicated lanes are paved with heavy-duty concrete designed to withstand the constant pounding of multi-ton vehicles. Or at least, they were supposed to be.

During construction, problems emerged with the concrete used for the dedicated roadways. The scale of the issue became clear by 2012, when Bogotá's secretary of finance announced that the entire line along Avenida Caracas—one of the original routes from phase one—should be rebuilt. Parts of the Avenida 26 line needed reconstruction as well. The estimated cost to the city was 1.6 trillion Colombian pesos, or roughly 500 million US dollars.

For a system that was supposed to be the affordable alternative to rail, half a billion dollars in premature reconstruction costs represents a significant asterisk.

Mechanical Failures

Throughout 2017 and 2018, TransMilenio buses developed a reputation for spectacular mechanical failures. Buses caught fire due to mechanical problems. In at least one incident, a bus literally broke in half. Tires flew off moving buses and struck nearby vehicles. Passengers reported water pouring into buses during rainstorms.

These incidents undermined public trust in the system's basic safety. When you board a bus wondering whether it might spontaneously combust or shed its wheels, the overall experience suffers regardless of how efficiently the system moves through the city.

What TransMilenio Still Gets Right

Despite the litany of problems, TransMilenio remains a remarkable achievement. The system moves millions of people daily through a city of over eight million inhabitants. It does so at a fraction of the cost of the subway systems that wealthier cities struggle to build and maintain.

The station design incorporates genuinely useful features. Electronic boards display approximate arrival times for incoming buses. Wait times are typically short because frequencies are high. Station attendants provide assistance. System maps are posted throughout.

The fare structure is straightforward: 3,200 Colombian pesos for a single trip as of 2025, roughly 75 US cents. Payment uses contactless smart cards, and multiple trips can be loaded onto a single card. Once inside the system, transfers between trunk lines and feeders are included.

The six different station types serve distinct functions. Simple stations appear every 500 meters or so for local service. Transfer stations allow passengers to change between lines through underground tunnels. Portal stations at the city's edges connect to intercity bus services and the feeder network. The diversity of station designs reflects thoughtful planning about how people actually move through an urban area.

The Missing Technology

One notable absence from TransMilenio's infrastructure is transit signal priority. The buses are not equipped with transponders that would allow them to communicate with traffic lights and receive green signals as they approach intersections.

This might seem like a minor technical detail, but it has significant implications. Signal priority can dramatically improve travel times and schedule reliability by reducing the randomness of how long buses wait at red lights. Many modern BRT systems incorporate this technology as standard.

Angelica Castro, a former general manager of TransMilenio, has publicly expressed regret about this omission. It represents a relatively inexpensive improvement that could meaningfully enhance the system's performance—and it remains unimplemented decades after the system opened.

Future Expansion

TransMilenio continues to grow. The system now extends beyond Bogotá proper into Soacha, a neighboring municipality that has effectively merged with the capital to form a continuous urban area.

A new line along Carrera Séptima—one of Bogotá's major north-south arteries connecting the downtown to northern neighborhoods—is under consideration. The proposal has attracted criticism because certain locations along the route may not physically accommodate the standard TransMilenio infrastructure. Whether and how this line gets built will test the system's ability to adapt to challenging conditions.

The Broader Lesson

TransMilenio embodies a tension that runs through urban planning worldwide. On one hand, it demonstrates that cities don't need to wait decades and spend billions to dramatically improve public transit. The transformation of Bogotá's mobility in just a few years proves that rapid, meaningful change is possible.

On the other hand, TransMilenio shows that success creates its own problems. Build a system that works, and people will use it—potentially far more people than the infrastructure was designed to handle. The overcrowding, the delays, the degraded experience that drove approval ratings into the basement all stem, in part, from the system's own effectiveness at attracting riders.

Most cities that have adopted TransMilenio-style BRT have done so as a complement to traditional rail rapid transit, not a replacement for it. Mexico City's Metrobús runs alongside an extensive subway network. Santiago's bus system feeds into metro lines. The lesson these cities drew from Bogotá may be subtly different from the one Peñalosa intended: not that buses can replace trains, but that buses and trains together can serve cities better than either alone.

Whether Bogotá itself eventually builds the subway that Peñalosa cancelled remains an open question. For now, the cherry-red buses continue their routes along the troncales, carrying millions of commuters through a city that, for better and worse, bet its mobility future on rubber tires and dedicated lanes.