A bus rapid transit system (BRT) is a high-capacity transport system with its own right of way, which can be implemented against relatively low cost. It is a key technology in cities in developing countries, which can change the trend of modal shifts towards more private vehicles towards public transportation, thereby bringing about a range of benefits, including reduced congestion, air pollution and greenhouse gases and better service to people in developing countries.
A bus rapid transit system (BRT) is a high-capacity transport system with its own right of way, which can be implemented against relatively low cost. It is a key technology in cities in developing countries, which can change the trend of modal shifts towards more private vehicles towards public transportation, thereby bringing about a range of benefits, including reduced congestion, air pollution and greenhouse gases and better service to people in developing countries. Its main drawback compared to other urban transport systems is its demand for urban space. To be most effective, BRT systems (like other transport initiatives) should be part of a comprehensive strategy that includes increasing vehicle and fuel taxes, strict land-use controls, limits and higher fees on parking, and integrating transit systems into a broader package of mobility for all types of travelers (IPCC, 2007)
With regard to the core elements of a BRT, the Institute for Transport and Development Policy (ITDP, 2013) states that the most important ones are:
- Dedicated right-of-wayto ensure that the buses can move quickly and unimpeded by congestion. Dedicated lanes matter the most in heavily congested areas. Intersections should be set up in order to maximise the green signal time for the bus lane. Passing lanes at stations allow additional travel time savings. In addition, stations should be located at least forty metres from intersections to avoid delay.
- Rapid boarding. This should be enabled by off-board fare collection and pre-board fare verification. Also, having the bus station platform level with the bus floor is an important way to reduce boarding and alighting times per passenger.
- Multiple routeswith free transfers between lines. Stations in the middle of the road serving both directions make transfers more convenient.
- Apeak frequencyof preferably at least 8 buses per hour, and an off-peak frequency of at least 4 buses per hour.
- Acontrol centrefor monitoring bus operations, identifying problems and rapidly responding to them. Automatic vehicle location technology through for example GPS to manage vehicle movements should be integrated.
- Clean vehicle technologiesto reduce emissions in order to decrease greenhouse gas emissions as well as to improve the health of the passengers and the urban population at large.
- Good pavement qualitywhich ensures better service and operations for a longer period by minimising the need for maintenance.
- Safe and comfortable stationswith an internal width of at least three metres. The stations should be weather protected and have security. The distance between the stations should on average be between 300 and 800 metres. Multiple docking bays per stations help provide multiple services at the same time.
- Excellence in marketing and customer service. This includes a unique brand and identity, clear route maps and signage, and real-time passenger information both on stations and buses.
- Accessfor special-needs customers, but also safe access for all pedestrians without dangerous road crossings. A secure bicycle parking at the station and bicycle lanes to the stations are needed to encourage bicycles as feeders to the BRT system.
- Integration with other public transport, which includes physical transfer points, an integrated fare system and integrated information.
Generally speaking, BRT is a very suitable technology for urban transport systems, both in developed and developing countries. It should mainly be seen in competition with types of mass rapid transit (MRT) systems, mainly rail-based systems such as metro or light rail. The main advantage of a BRT compared to other MRT options is the substantially lower investment cost, while its main drawback is its demand for space in a city. In many cases, when BRTs are being constructed, road space for private vehicles is reduced, as there may be no opportunity to expand the total road space.
The precise characteristics of each BRT strongly depend, among others, on the local market, the operational and physical application environment and available resources.
International experience has shown various successful and unsuccessful examples of BRTs, from which important lessons about how to introduce and maintain a BTR can be drawn. Caldés et al. (2007) note that the following should be taken into account:
- Public acceptance of the BRT and awareness of the diverse benefits (social, environmental, etc)
- Appropriate consideration of non-technical aspects
- Careful planning, for example in order to avoid bus overcrowding during peak periods.
- Possible resistance by existing bus operators, with negative consequences on the initial implementation.
- Transparency and good practices in all steps of the project in order to avoid any risk of money misuse and political tensions
- Appropriate fare collection systems
- Good pavement maintenance
International experience shows that it is common that some problems occur in the initial phase of operations. However, most implementation problems can be gradually solved.
Curitiba’s (Brazil) integrated transportation network is often mentioned as the first BRT in the world, being in operation since the 1970 (IPCC, 2007) and is now used by over 70% of its commuters (Goodman et al. 2006). It has served as a source of inspiration for many other cities in South and North America, but it was not until after the year 2000 that BRTs were becoming popular, with landmark examples such as TransMilenio in Bogota, TransJakarta, and Metrobus in Mexico City. As of now, BRTs is a fully market-ready technology, and has been implemented successfully in dozens of cities in both developed and developing countries (BRT Policy Center, 2010).
As of 2010, over one hundred BRTs are being constructed in Latin America, Africa and Asia. BRTs are generally seen as an option with considerable potential in cities in the developing world. Worldwide there are almost 30 million BRT passengers per day in 163 cities with a combined BRT covering a length of 4,256 km (according to BRTdata.org).
BRTs can make an important contribution to a sustainable urban transport system. It is more energy efficient than conventional bus systems per person-kilometre due to the higher speeds and higher capacity buses. Also it may improve the modal split towards more use of public transport. Many economic, social and environmental benefits of BRT have been identified (ITDP, 2007):
- Reduced travel time
- More reliable product deliveries
- Increased economic productivity
- Increased employment
- Better work conditions
- More equitable accessibility throughout the city
- Less accidents and illness
- Increased civic pride and sense of community
- Reduced emissions (CO, SOx,NOx, particulates, CO2)
- Reduced noise levels
According to Hughes and Zhu (2011), the implementation of bus rapid transit can have at least six potential impacts on greenhouse gas emissions on a certain corridor:
- Induced modal shift to BRT from more emission-intensive modes.
- Increased fuel efficiency due to increase in mixed traffic speeds: significant increases in overall traffic speed can be achieved by removing many frequent stop buses.
- Reduced vehicle kilometres travelled due to rationalised routes.
- Increased fuel efficiency of buses due to improved transit vehicle speed.
- Improved bus fuel efficiency of new buses and the scrappage of old buses.
- Decreased auto trips due to the development of transit-supportive land uses and decreased household motorisation rates.
For Sub-Saharan countries, Gouvello et al (2008) estimated a GHG reduction potential of 12 MtCO2e per year in 2020. Few studies however have given detailed estimates about the actual mitigation potential of BRTs, partly due to a lack of detailed data and the very large differences in vehicle mix and travel patterns (IPCC, 2007). The World Bank estimates that in Mexico, the introduction of 20 BRT corridors (in addition to the 3 operational ones in Mexico City and Leon) including supporting measures could lead to a reduction of 2 MtCO2e per year.
In Mexico City, local airborne pollutants were measures before and after the implementation of the main BRT corridor. Concentrations of CO, PM2.5, PM10, and benzene show a significant decrease for Metrobus, the BRT system (see Figure 2)
Estimates for investment cost for BRT systems vary widely. Depending on the required capacity, urban context and complexity of the project, BRT systems can be delivered for $ 1 - 15 million per km (IPCC, 2007), with most existing BRTs in developing countries in the lower part of this range (ITDP, 2007). These figures are substantially lower than those for rail-based systems, which cost approximately $ 50 million per km (IPCC, 2007).
For China, the incremental cost of implementing BRTs have been estimated at 2.6 $/tCO2 (CCAP/Tsinghua, 2006). For Latin American cities, costs for BRTs were estimated to be 14-66 $/tCO2, depending on the policy package involved (IPCC, 2007).
The Global Environment Facility has funded 33 BRT project so far, accounting for a 32% share of the total GEF funds. Multilateral Development Banks traditionally focus on finance for road construction, but are shifting their focus more towards sustainable transport including BRTs (Huizenga & Bakker, 2009).
The Clean Development Mechanism can provide an opportunity to co-finance a BRT, as well as providing an additional incentive (‘international image’) for local governments to invest in such projects. A general barrier for BRT projects under the CDM are however the high data requirements of the CDM methodologies, as well as demonstrating additionality, i.e. why the project would not be implemented without the CDM (Huizenga & Bakker, 2009).
[this information is kindly provided by the UNEP Risoe Centre Carbon Markets Group ]
As of March 2011, there are 13 BRT projects in the CDM pipeline, out of which 2 are registered and for 1 project CERs have been issued.
The project involves the establishment of a sustainable mass urban transport system. The system consists of large capacity busses, which work in a new infrastructure where the busses operate in dedicated lanes. The infrastructure also supports easy access to the platforms where passengers are able to board or disembark the vehicles. The infrastructural changes also include a ticketing system which allows pre-board ticketing. The general structure of the Bus Rapid Transit system also involves an improved bus management system moving from many independent enterprises competing at bus-to-bus level to a consolidated structure with formal enterprises competing for concessions. (UNFCCC project ref. no.: 672)
Project CO2 reduction over a 7 year crediting period: 1'725'940 tCO2 (per/year: 246'563)
BRT Policy Center: http://www.gobrt.org/resources.html 
Global BRT Data. http://www.brtdata.org/ 
Caldes, N., Izquierdo, L. and Labriet M., 2007. Sectoral best practices: Case studies on how to simultaneously improve urban air quality and mitigate climate change. Available at: http://curbair.org/proj_res/ 
CCAP/Tsinghua University, 2006. Greenhouse Gas Mitigation in China: Scenarios and Opportunities through 2030. Available at: www.ccap.org 
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Goodman, J., Laube, M. and Schwenk, J., 2006. Curitiba’s Bus System is Model for Rapid Transit.
Goodman, J., Laube, M. and Schwenk, J., 2005/2006 Schwenk Race, Poverty & the Environment, UN Habitat. Available at: http://urbanhabitat.org/files/25.Curitiba.pdf 
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Hidalgo, D., 2007. Bus Rapid transit Bogota´s Transmilenio and lessons in Asia
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IPCC, 2007. Transport and its infrastructure. In Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Metz, B. and Davidson, O.R. and Bosch, P.R. and Dave, R. and Meyer, L.A. (eds)], Cambridge University Press, Cambridge, United Kingdom and New York, USA. Available at: http://www.ipcc.ch/pdf/assessment-report/ar4/wg3/ar4-wg3-chapter5.pdf 
ITDP, 2007. BRT planning guide. Available at: http://www.itdp.org/index.php/microsite/brt_planning_guide/ 
ITDP, 2013. The BRT Standard 2013. Available at: http://www.itdp.org/microsites/the-brt-standard-2013/ 
UNEP/Risø, 2010. UNEP Risoe CDM/JI Pipeline Analysis and Database. Available at: www.cdmpipeline.org 
World Bank, 2009. Clean Technology Fund Investment Plan for Mexico. Available at: http://www.climateinvestmentfunds.org/cif/Country%20Investment%20Plans