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 poor people. Its main drawback compared to other urban transport systems is its demand for urban space.
A bus rapid transit system (BRT) is a high-capacity transport system with its own right of way, and can be described as being a systematic combination of infrastructure (busways, stations, terminals) with organized operations and intelligent technologies to provide a higher quality experience than possible with traditional bus operation (Hidalgo, 2007). 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 regards to the core elements of a BRT, Wright & Fulton (2005) states that the most important ones are:
- Exclusive right-of-way lanes
- Rapid boarding
- Enclosed stations that are safe and comfortable
- Clean vehicle technologies
- Excellence in marketing and customer service
- Pre-board fare collection and fare verification
- Clear route maps, signage, and real-time information displays.
- Automatic vehicle location technology to manage vehicle movements
- Free transfers between lines
- Modal integration at stations and terminals
- Competitively-bid concessions for operations
- Effective reform of the existing institutional structures for public transit
ITDP (2007) gives very detailed guidelines with respect to the proper planning of a BRT system.
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 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 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.
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. Thereby it contributes to the following aspects of sustainable development:
- Reduction of air pollution
- Reduction of GHG emissions
- Congestion reduction
- Increase in energy supply security, due to reduction for imported oil
- Social equality and poverty reduction by providing affordable high-quality transport
- Economic prosperity by reducing travel times and congestion
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 
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CCAP/Tsinghua University, 2006. Greenhouse Gas Mitigation in China: Scenarios and Opportunities through 2030. Available at: www.ccap.org 
Dalkmann, H. and Brannigan, Ch., 2007. Sourcebook transport & climate change. Available at: http://www.gtz.de/de/dokumente/en-transport-and-climate-change-2007.pdf 
Goodman, J., Laube, M. and Schwenk, J., 2006. Curitiba’s Bus System is Model for Rapid Transit.
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ITDP, 2007. BRT planning guide. Available at: http://www.itdp.org/index.php/microsite/brt_planning_guide/ 
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 
Wright, L. and Fulton, L., 2005. Climate change mitigation and transport in developing nations. Transport reviews, (25), pp. 691-717