TransMilenio is a bus rapid transit (BRT) system that serves Bogotá, the capital of Colombia, and Soacha, a neighbouring city. The system opened to the public in December 2000. As of 2024, 12 lines totalling 114.4 km (71 mi) run throughout the city. It is part of the city's Integrated Public Transport System (Sistema Integrado de Transporte Público [SITP]), along with the urban, complementary and special bus services operating on neighbourhood and main streets.

TransMilenio consists of several interconnected BRT lines, with raised floor stations in the center of a main avenue, or "troncal". Passengers typically reach the stations via a bridge over the street. Usually four lanes down the center of the street are dedicated to bus traffic. The outer lanes allow express buses to bypass buses stopped at a station.

As of the 4th quarter of 2023, 1,836 buses on average were circulating on the trunk line system. An additional set of 869 regular buses, known as "feeders" (alimentadores in Spanish), carry passengers from certain important stations to many different locations that the main route does not reach. Unlike the main TransMilenio buses, feeders operate without dedicated lanes, are not articulated and are either green or blue (regular TransMilenio buses are red). There is no additional fare to use the feeder buses.

There are 27 bicycle parking facilities in main TransMilenio stations with 7,351 parking spaces to facilitate cyclists using the system. Eight BRT corridors were certified in 2013 to meet the BRT standard with excellence: Autonorte and Caracas silver, Americas, Calle 80, Eldorado, NQS and Suba gold.

Before TransMilenio, Bogotá's mass transit "system" consisted of thousands of independently operated and uncoordinated mini buses. There was also a plan for a network of elevated highways throughout Bogotá, and plans to build a subway as Medellín had done seven years prior. When Enrique Peñalosa was elected mayor he cancelled these projects and oversaw the construction of the initial TransMilenio system at a fraction of the cost.

The mayor created a special company to build the project and run the central system. The operational design of TransMilenio was undertaken by transport consultants Steer Davies Gleave with the financial structuring of the project led by Capitalcorp S.A., a local investment bank. Most of the money required to build TransMilenio was provided by the Colombian central government, while the city of Bogotá provided the remaining 30%.

Within three years after the initiation of the project, the first phase opened in December 2000, covering Caracas Avenue and 80 street. Other lines were added gradually over the next several years. Prior to construction, a 30 km trip by public transport would take 2 hours and 15 minutes in 1998; the same trip using TransMilenio now takes 55 minutes.

In the beginning, most buses were diesel-powered, purchased from such manufacturers as the Colombian-Brazilian company Marcopolo-Superior, German conglomerate Mercedes-Benz, and Swedish companies such as Volvo and Scania. The buses were articulated and had a capacity of 160 passengers each. In May 2007, a new, larger bi-articulated bus, with capacity for 270 passengers, was presented to the public.

Bogotá won the first Sustainable Transport Award in 2005 due to the BRT system and urban cycling strategy.

On May 2 and 3, 2006, several groups of bus drivers not associated with TransMilenio held a strike, protesting against some elements and consequences of the system. They disagreed with the amount of monetary compensation that they would receive in exchange for the disposal of old buses (10 to more than 20 years old), traffic restrictions on the TransMilenio main lines, and a new Pico y Placa Ambiental in some city areas, that would restrict the schedules of buses older than 10 years to early morning hours to reduce pollution in the city.

Since the May 2006 expansion, the TransMilenio route system has changed dramatically, with new sections added to the system.

Due to the relatively high price, overcrowding, and delays in the routes, hundreds of people, mostly students protesting and some vandals looted and broke windows on March 9, 2012, causing half a million dollars of damage and 11 injuries. The vandals were confronted and detained by riot police.

At the end of 2018, Transmilenio ordered 1383 new buses as a replacement of the older ones in service. 52% were compressed natural gas (CNG) buses made by Scania with Euro 6 emission rating, 48% were diesel engine made by Volvo with Euro 5 emission rating. More orders have produced an impressive result: "To improve public and environmental health, the City of Bogotá has assembled a fleet of 1,485 electric buses for its public transportation system—placing the city among the three largest e-bus fleets outside of China."

Bogotá won the Sustainable Transport Award again in 2022 also thanks to the continued expansion and success of TransMilenio.

TransMilenio has 12 lines serving 152 stations in the cities of Bogotá and Soacha:

• A Caracas between Calle 76 and Tercer Milenio: 14 stations
• B Autonorte between Terminal and Héroes: 17 stations
• C Suba between Portal de Suba and San Martín: 14 stations
• D Calle 80 between Portal de la 80 and Polo: 14 stations
• E NQS Central between La Castellana and Tygua - San José: 13 stations
• F Américas between Portal de Las Américas and Avenida Jiménez: 18 stations (including Ricaurte station)
• G NQS Sur between Comuneros and San Mateo: 17 stations
• H Caracas Sur between Hospital and Portal de Usme and Portal del Tunal: 16 stations
• J Eje Ambiental between Museo del Oro and Universidades: 3 stations
• K Calle 26, between Portal Eldorado and Centro Memoria: 13 stations
• L Carrera Décima between Portal 20 de Julio and San Diego: 10 stations
• M Carrera Séptima: Museo Nacional: 1 station

Instead of being numbered, routes have a combination of letters and numbers. In order to fill the information gap, TransMilenio made available an interactive guide that includes routes, stations, nearby places and route combinations.

Construction of a new line in Carrera 7 (North-Downtown) is under consideration. This has been criticized as there are certain locations where the system might not fit.

TransMilenio buses are not equipped with transponders to give them signal priority. Regret over this decision was voiced by the former general manager of the system, Angelica Castro.

There are six types of stations:

• Sencillas (Simple): local service stations, located approximately every 500 m
• De transferencia (Transfer): allow transfer between different lines through a tunnel
• Sin intercambio (No transfer): do not allow transfer between lanes (north-south, south–north, west–east, east–west); located in the Autopista Norte (due to a stretch of the road), Tunal and 6th Street ramification (due to water channels).
• Intermedias (Intermediate): service both feeder and trunk line.
• Cabecera (Portal): near the entrances to the city. In addition to feeders and articulated buses, intercity buses from the metropolitan area also arrive at these stations.
• Paraderos bus dual (dual-bus stop): located in the streets, these stops don't have turnstiles, electronic boards and the floor level is the same of the street; served by buses with station-level and street-level doors. These stops are located in the pretrunk corridors (AK 7, AV Caracas, AV Suba, AC 80, AV El Dorado).

All stations have electronic boards announcing the approximate arrival time of the next bus. Wait times are short as there is usually a bus serving the station. There are also station attendants to provide assistance to the passengers, and posted system maps.

Users pay at the station entrance using a smart card, pass through a turnstile, and wait for buses inside the station, which is typically 5 m wide. The bus and station doors open simultaneously, and passengers board by walking across the threshold. The elevated station platform and the bus floor are at the same height.

TransMilenio stations comply with easy access regulations because they are elevated and have ramps leading to the entrance. The alimentadores (feeders) are normal buses without handicapped accessibility. A lawsuit by disabled user Daniel Bermúdez caused a ruling that all feeder systems must comply with easy access regulations by 2004, but this has not happened yet.

The zoning divides the trunks into 12 lines or zones that have different letters and colors. The maps changed at each station, to show the specific services to the station in question and the way to reach the other zones of the system from there.

The trunk system has three types of services:

• Regular Routes (Ruta Fácil): These are the numbered routes from 1 to 9 that stop at all stations and work all day. As of August 2008, this type of service was called the Easy Route. On June 17, 2017, these services were modified, replacing the routes that operated since 2006 by shorter trails, in addition to a change of nomenclature, which did not include the letter and the color of the destination area.
• Express (Expreso): Routes that only stop at the stations determined in their route, and are numbered from 10 to 75.
• Dual bus trunk (Troncal Bus Dual): Routes to extend the TransMilenio trunk service to arteries, beginning with the Carrera Séptima.

Services rendered since April 29, 2006

Type	North routes	South routes
Regular Routes (Ruta Fácil) All day	1 2 3 4 5 6 7 8	1 2 3 4 5 6 7 8
Express Every day All Day	B10 K10 B12 B75 C15 C19 D22 M47	D10 F19 G12 G22 G47 H15 H75 L10
Express Monday to Saturday All day	B11 B13 B16 B18 B23 B72 B74 C17 D20 D21 D24 B44 J23 K43 K54 M51	F23 F51 G11 G43 G44 H13 H17 H20 H21 H54 H72 J24 J74 K16 K23 L18
Express Monday to Friday Peak morning time	A52 B52 B55 B56 D50 E32	J70 J73
Express Monday to Friday Peak evening time	C73	F32 F62 G52
Express Monday to Saturday Peak morning time	B28 B71 D51 G45	F28 G45
Express Monday to Friday Peak morning and evening time	B27 B28 B50 C29 C30 G45	C50 F28 F29 G30 G45 H27 H73
Express Saturdays from 5:00 a.m. to 3:00 p.m.	C30	G30
Express Sundays All day	K42	G42
Dual Every day All day	C84D81M82M83M86	H83K86L82M81M84
Alimentador - Intermunicipal	1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 2.1 2.2 2.3 2.4 2.5 2.7 2.8 2.10 2.11 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.13 4.1 4.2 4.3 5.1 5.2 5.3 5.4 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 6.12 7.1 7.2 7.3 8.1 8.2 8.3 8.4 8.5 8.6 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 9.10 9.11 10.1 10.2 10.3 10.3C 10.4 10.5 10.6 10.8 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 11.9 11.10 12.1 13.6 13.7 13.9 13.10 13.12 13.13 16.1 16.2 16.3 16.4 16.5 16.6 16.7 16.8 16.9 16.10 16.13 16.14

The fare as of 2023 is 2,950 Colombian pesos for a single trip (about €0.7 or US$0.75). Cards use a contactless smart card (MIFARE) system, and multiple trips may be purchased using one card.

Fare of TransMilenio

Year	Rush hour COP	Regular hour COP
2023	$2950
2022	$2650
2021	$2500
2020	$2500
2019	$2400
2018	$2300
2017	$2200
2016	$2000
2015	$1800
2014	$1800	$1500
2013	$1700	$1400
2012	$1700
2011	$1750
2010	$1700
2009	$1600
2008	$1500
2007	$1400
2006	$1300
2005	$1200
2004	$1200
2003	$1100
2002	$1000
October 2001	$900
February 2001	$850
2000	$800

According to a United States Transportation Research Board (TRB) case study report, the initial construction cost for the first phase of 41 km was US$240 million, or US$5.9 million/km. In a report presented later by the Ministry of Transport of Colombia, the total cost of the construction of Transmilenio phase one was estimated at 1.4 billion COP (about US$703 million), of which 253.053 million COP (about US$126.5 million) was provided by the Colombian government. The construction of the phase two was estimated at 3.2 billion COP (about US$1634 million), of which 2.1 billion COP (about US$1058 million) was provided by the Colombian government and the rest was provided by the city. The numbers of this report are calculated in money of 2009.

The system is overseen by a public body, which awards contracts to private bus companies on a competitive basis. According to TRB, private contractors are paid based on the total number of kilometers that their vehicles operate.

Daily ridership quickly reached 800,000 after the system opened. TransMilenio has since been expanded. Ridership in early 2006 was 1,050,000 daily, in 2009 it was 1,400,000 daily and in September 2018 it was 2.4 million on a weekday.

Other cities are building systems modelled on Transmilenio, for example, Mexico City, and Transantiago in Santiago, Chile, however, in these cities the system is complemented with a Rapid transit system.

In 2016, Transmilenio had an 86% disapproval rating from users. User strikes erupted over bad service quality, with users blocking bus lanes and at times halting the entire system. These protests sometimes devolved into riots involving heavy police presence and the use of crowd control measures such as tear gas and water cannons.

The system was described by users, independent bodies and the media as suffering from overcrowding with an average of eight passengers per square meter, insecurity and providing bad customer service. During rush hours, "stations are so packed that people can't get off the bus". In some stations, overcrowding was so severe that users had to wait in a long line to top up their Smart card and another line to enter the station. According to official data in 2017, there were 3404 thefts in TransMilenio stations and 1442 more on buses.

During construction, there were problems with the concrete used to pave the dedicated roads, which had an estimated cost to the city of 1.6 trillion pesos (500 million dollars). In 2012, Bogota's secretary of finance said that the whole line of Avenida Caracas should be rebuilt as well as some parts of the Avenida 26 line.

In 2015 a study made by the National University of Colombia revealed that 70% of the air pollution near Transmilenio exits was caused by the buses of the first phase. According to official data, more than 50% of the first and second phase buses broke atmospheric emissions rules. There was controversy around the fact that the Transmilenio buses were diesel-powered. Some academics, councillors and citizens called the buses dangerous as diesel fuels are carcinogens according to the World Health Organization, and pointed out calls to ban them in other cities like Stuttgart and Stockholm.

Women in Bogotá have stated that the overcrowding in the system makes it easy for criminals to attack women and go unnoticed. According to a 2012 survey conducted by the Secretary for Women's Issues of Bogotá, 64% of women said they have been victims of sexual assault in the system. Several policies have been adopted in order to confront this problem, like an exclusive bus for women, and special undercover policewomen. However, no measures have been effective against the problem, and sexual assaults continued to occur in 2018.

In 2017 and 2018, many incidents with Transmilenio buses had been reported while they were operating. There have been cases of buses being burned due to mechanical problems, one bus broken in half, tires flying off the buses and hitting cars, and users reporting that water leaks into the buses when it rains.

• List of bus rapid transit systems
• TransMiCable
• Transjakarta

• Official website of TransMilenio (in Spanish)
• Bogota's New Transit System, a TransMilenio slideshow by the New York Times
• The Economics of TransMilenio, an economic analysis of Bogotá's BRT system

4°38′56″N 74°06′31″W / 4.6490°N 74.1086°W / 4.6490; -74.1086