The IPCC report for 2014 states in its Summary for Policymakers that “the transport sector accounted for 27 % of final energy use and 6.7 GtCO2 direct emissions in 2010, with baseline CO2 emissions projected to approximately double by 2050,” and that a greater investment in “all transport modes, plus new infrastructure and urban redevelopment investments, could reduce energy demand in 2050 by around 40% below the baseline…” Bus Rapid Transit (BRT) is one such mode that has become increasingly popular in recent years. With its cutting-edge advancements and seemingly moderate costs, it has emerged as one of the leaders of urban transit systems in the first part of the twenty-first century. From Bogotá to Cape Town to Guangzhou, the BRT model has lit a fire of innovation that now burns in over 165 cities (and counting) around the globe. On the surface, the system seems to sing a song of transit redemption that is pleasing to the ears of all who listen; but as a newcomer to the fields of urban planning, transportation, and environmental studies, one must inquire more deeply as to whether BRT is a viable and valuable option. This includes learning the history and true definition of a BRT system, assessing whether it is an effective and economically feasible mode of transportation for reducing greenhouse gas emissions, and investigating its environmental impacts. It is also imperative to understand the current political debates surrounding BRT, particularly if it is a practical transit option for coastal cities. The intent of this paper is to answer the above questions, and in so doing, determine the value of BRT as a viable and sustainable transit implementation in vulnerable coastal cities.
Defining Bus Rapid Transit: A Brief History
Although there is no rigid definition of what constitutes BRT, there are a number of scholarly sources that, when synthesized, give clear suggestions as to what bus rapid transit really is. In their literature review of recent developments in bus rapid transit, TaoTao Deng and John D. Nelson divulge the basic concept and components of a BRT system. They start by defining the term ‘mass transit’ as a large-scale system of public transport serving a city or metropolitan area, characterized by fast running speed, high passenger-carrying capacity and mostly operating on an exclusive right-of-way. Knowing that BRT falls under this grand umbrella definition of mass transit systems helps to clarify the difference between it and a regular bus system. Deng and Nelson emphasize this difference by drawing upon a number of sources that work cohesively to “set BRT apart from the conventional bus system, describing BRT as a form of ‘rubber-tyred rapid transit, providing high-quality service’.” These definitions state that BRT is “a rapid mode of transportation that can combine the quality of rail transit and the flexibility of buses,” that it is “a flexible, rubber-tyred form of rapid transit that combines stations, vehicles, services, running ways, and ITS elements into an integrated system with a strong identity,” and that it is “a rubber-tyred rapid transit service that combines stations, vehicles, running ways, a flexible operating plan, and technology into a high quality, customer focused service that is frequent, fast, reliable, comfortable and cost efficient.” In addition to the provision of the above definitions, the authors also include a table that highlights the main components of a BRT system (see Table 1), thus providing a definitive and comprehensive look into the makeup of this unique mode of mass transportation.
Though the popularity of its use in Latin America and Asia suggests otherwise, the origins of the BRT concept can be traced back to 1939 Chicago where the first exclusive bus lane on a city street was built and later inspired the USA’s development of the ‘busway’ concept. According to Deng and Nelson, “The busway was built to avoid traffic congestion and provide reliable service in many cities,” with the first true busway being placed on the Henry G. Shirley Memorial Highway in Virginia in1969, followed by a guided corridor in the UK in 1971, Germany in 1980, and in many other places around the world. However, despite the origins of BRT being credited to the United States, the authors affirm that the concept in its most modern sense was developed by Latin American planners looking for a quick and inexpensive way to speed up buses as a solution to deteriorating traffic conditions.
Is BRT Effective? The Cases of Curitiba and Bogotá
The frontrunner of the innovative BRT systems in Latin America is the Rede Integrada de Transporte (RIT) in Curitiba, Brazil. Deng and Nelson describe its development:
“In Curitiba, the first busway opened in 1974, operating in the high-demand, lower income district on the periphery of the city. The early simple busway system gradually evolved to an advanced BRT system including five busway corridors and integration with extensive feeder bus services. Curitiba’s BRT system uses bi-articulated buses and well-designed ‘tube’ stations to expand corridor capacity. The 25-metre long buses operate on median exclusive busway, capable of carrying 260 passengers each… Serving as the backbone of Curitiba, BRT has provided a range of benefits for the city. The efficient BRT has substantially reduced travel time and fuel consumption, which helps to promote sustainable urban development. Curitiba’s BRT has successfully attracted mode shift. Even though Curitiba has one of the highest car ownership rates in Brazil, one rider survey (1991) suggested that 25% of these commuters who previously used car had switched to using the BRT service.”
Mode shift is one of the more substantial steps an auto-centric city can take toward becoming a more sustainable community, yet it is also one of the more difficult to implement. If the fact that a single BRT system was able to incite change among at least 25% of a population of 609,000 to change their commuting routine is not enough to prove its effectiveness, the added support of its travel time reductions and fuel consumption make the claim nearly undeniable.
The success of the RIT resulted in a number of Latin American cities adopting the BRT concept and integrating into their own infrastructure. One of the more salient examples of these is the TransMilenio system in Bogotá, Colombia. TransMilenio was developed by Bogotá City and opened in 2000 with a goal of promoting higher use of public transport, cycling, and walking. Its components consist of dedicated busway, articulated buses, enhanced stations, smart card-based fare collection system, advanced control system, distinctive image, and an affordable cost for low-income users. Deng and Nelson conclude that, “after several years progress, the TransMilenio has achieved impressive results in travel time saving, considerable passenger satisfaction, high capacity, accident and emission reduction, and operation without subsidy.” With the initial evidences of RIT’s potency, and the reinforced success of TransMilenio, the BRT concept appears to be a cogent model for effective transportation planning.
In reaction to the notion of Curitiba and Bogotá’s BRT-induced effectiveness, Duarte and Rojas submit, “Although the BRT systems in Bogotá and Curitiba have become international references, some local critics suggest that they have reached their maximum capacity.” There are also questions of intermodal connectivity raised, as the authors suggest, “multimodality is…a fact of life.” Within these concerns, there is special attention paid to pedestrian accessibility. In the case of Curitiba, only 55 percent of terminals in Curitiba have pedestrian-friendly access. In some instances, the access was considered to be only partial because of the poor quality of the sidewalks and the absence of disability ramps. Even though “only one terminal is not adapted for people with reduced mobility, and the situation is very good inside the terminals…39 percent of people with reduced mobility have difficulties gaining access.”
Bogotá faces very similar challenges with pedestrian accessibility. Duarte and Rojas state that even though all platforms are adapted for people with reduced mobility, access to terminals from the street for these users is nonexistent at all terminals at the ends of routes, and only four of the intermediate terminals have facilities for disabled people (see example in Figure 1).
Despite the questions of intermodal connectivity in Curitiba and Bogotá, the overall conclusion regarding BRT’s success remains. If it is assumed that a BRT system’s success or effectiveness is defined by whether it reaches the originally mentioned goal of Latin American planners—that is goal of creating a quick and inexpensive way to speed up buses as a solution to declining traffic conditions—then the cases of Curitiba, Brazil and Bogotá, Colombia provide shining examples of effective BRT implementation.
Apart from the efficiency of BRT in terms of throughput and vehicles, additional studies have observed that the RIT and TransMilenio have also offered a number of increased health benefits to their riders. In Bogotá, for example, the authors highlight research findings claiming that “people who live in close proximity to a TransMilenio station are more likely to be irregularly active when compared with inactive people.” The case of Curitiba had similar results, concluding that 55% of the population of Curitiba reported walking and 8% reported cycling as a means of transport. Another interesting fact is that “a perception of traffic safety, measured as ‘presence of traffic and drivers exceeding speed limits’…was not associated with walking or cycling,” but that “moderate and high levels of perception of personal security, evaluated as ‘perception of crime nearby and perceived safety when walking or cycling at night and during the day’…were associated with both walking and cycling.” In other words, personal security was more important than the urban physical environment in influencing physical activity.
Though the RIT and TransMilenio systems act as shining evidence that BRT is in fact an effective use of time and investments for transportation planners, it is all in vain if the systems are not safe for their patrons. For the sake of consistency and controlled conclusions, it is of interest to discuss the observed safety of the one of the already highlighted systems. In 2012, Juan Pablo Bocarejo, Juan Miguel Velasquez, Claudia Andrea Díaz, and Luis Eduardo Tafur conducted an analysis of the impacts of the TransMilenio system on road safety in Bogotá, particularly regarding traffic accidents. In their study, they analyzed the number of recorded accidents along two busy city corridors, Caracas Avenue and NQS Avenue, over a 10-year span (between 1998 and 2008). Their paper includes the results of three specific types of analysis: hotspot analysis, accident analysis by road segment, and accident analysis at stations. What they found was “a significant drop in serious accidents (including injury and fatal accidents) over the 10 years between 1998 and 2008.” GIS analysis also shows that “the total number of accident hotspots along both corridors dropped, and that there were significant changes in the location of these spots.”
Although some of the new locations of hotspots included areas around the busiest stations, the authors’ findings suggest that there is “no link between the times when most serious accidents occur and the hours of highest demand on NQS Avenue,” (see Figure 2) but that, in contrast, Caracas Avenue shows a relationship “between the peak demand periods and the number of serious accidents and pedestrians hit which is consistent with the higher pedestrian flows that occur at stations during these times.”
In the end, the authors concluded, “the case of Bogotá shows that BRT has a significant potential to improve road safety in the main public transport corridors in developing cities,” and they highlight the fact that “in Bogotá, these benefits in road safety were largely unintended.” If the implementation of TransMilenio has unintentionally improved road safety in Bogotá, it is not invalid to conclude that a BRT system designed explicitly to be a safety-promoting infrastructure would do the same and more for the safety of everyone on the road.
BRT’s Role in Climate Change Mitigation
As planners and policymakers search for ways to mitigate carbon emissions in cities, new approaches to transportation will be vital. The IPCC’s Summary for Policymakers states that “the transport sector produced 7.0 GtCO2eq of direct GHG emissions (including non-CO2 gases) in 2010 and hence was responsible for approximately 23% of total energy-related CO2 emissions (6.7 GtCO2).” The panel then cautions readers that “without aggressive and sustained mitigation policies being implemented transport emissions could increase at a faster rate than emissions from the other energy end-use sectors and reach around 12 GtCO2eq/yr by 2050.” There are a number of studies which support the notion that Bus Rapid Transit can and should be an integral component to said policies.
One of the more notable of these studies appears in the Journal of Public Transportation. In it, authors Callaghan and Vincent explored the potential of BRT to be a tool for near-term reductions of GHG emissions in U.S. cities, particularly when compared to light rail transit (LRT). They conclude that “BRT can provide significantly greater CO2 reductions than LRT for most U.S. cities,” the main reason for which being “the generation mix of electricity used to power LRT,” with a secondary reason that, “BRT costs significantly less to build than LRT, and thus more can be deployed for a given budget.”
They expound even further, saying:
“Even without this additional benefit, the per passenger mile CO2 emissions for a BRT system are likely to be significantly lower than those of an LRT system almost anywhere in the country. The most significant potential appears to be if a number of cities, such as the signatories to the Mayors Climate Protection Agreement, each agree to use BRT as a CO2 reduction strategy. For example, if 20 cities each achieve results similar to what we found with the 40-ft CNG vehicles, they could achieve total reductions over 20 years in excess of 3 million metric tons. If these cities build additional corridors and make other changes over the 20 years, such as better integration of transit and land use, the reductions could be much higher still.”
Similar metrics have been found in other parts of the world as well. For example, a carbon footprint analysis in Xiamen City, China found while exploring transit expansion options found that the implementation of a BRT system “could achieve reductions of approximately 25,255 tCO2e per year compared to the no-build option.” Carbon emissions savings were also found in the already highlighted case studies in Curitiba and Bogotá. Whether it is fuel efficiency, reduced vehicle miles traveled, or the general influence on multimodality, the evidence points to BRT as an effective tool to notably curb emissions in the transport sector; especially in those areas whose current infrastructure is overwhelmingly auto-oriented.
Development Benefits of BRT in Coastal Cities
One of the greatest benefits of BRT systems is their ability to incite more centralized development patterns. This is particularly pertinent to cities in coastal territories whose populations are growing rapidly despite their increased vulnerability to global sea level rise. A population projection study by Neumann and company found that “about one third (30%; 189 million) of the global LECZ [low-elevation coastal zone] population was living in the 100-year flood plain in the year 2000…the number of people at risk from coastal flooding could reach between 268 million and 286 million in 2030” and “globally by 2060, up to 411 million people could be affected by extreme flooding events.” This means that in the coming years it will be critical for coastal cities to densify and reduce the amount of impervious surface area if they are to avoid exacerbating the already dreary flood conditions. One of the most actionable ways they can do so is to retrofit existing infrastructure and establish multimodal transport corridors which encourage infill development rather than sprawl. BRT has the power to influence such development while at the same time bringing economic value to areas of development.
Aiga Stokenberga addresses such scenarios in her review on how BRT affects urban development and property values. She starts by laying down the factors that land development around a public transport system depends on, which are “the increment of accessibility they offer, availability of vacant land, economic conditions, and land-use and transportation policy.” There is a notable emphasis placed on policy tools as a means of encouraging BRT implementation, particularly in a developing city context, stating that BRT systems complemented by supportive policies can also serve as tools for “promoting social and affordability goals, for instance, by incentivizing the concentration of affordable housing in BRT-accessible corridors.”
Stokenberga’s research continues by elaborating on and comparing a number of theoretical frameworks and research designs—such as cross-sectional versus before-after data, and type of price evaluated in property value studies—related to the works under review. She then takes a turn toward qualitative evidence of economic development around BRT systems, and optimistically states, “There is a large amount of qualitative and anecdotal evidence that the implementation of BRT services can lead to development…In the case of BRT system effects on land values and uses in Latin American cities, the qualitative findings are relatively encouraging.”
Latin America is not the only place where findings suggested that BRT does in fact promote development. A study of the effects of BRT on Seoul, Korea found that even in a crowded, congested, and land-constrained city like Seoul, “increased accessibility prompted property owners and developers to intensify land uses along BRT corridors…” This mainly included converting single-family residences to multi-family units, apartments, and mixed-use projects. Moreover, the findings showed evidence that “land markets capitalized these accessibility gains, particularly among parcels used for condominiums and higher density residential uses.” Land price premiums in the 5–10% range were estimated for residences within 300 m of BRT stops, while with retail shops and other non-residential uses, impacts were more varied, ranging from 3% to 26% premiums over a smaller impact zone of 150 m from the nearest BRT stop.
Apart from the case studies in Latin America and Seoul, BRT has also proven to be an effective development catalyst in coastal zone cities such as Lagos, Auckland, and Stockholm (among many, many others), and has the potential to do so in LECZ cities like New Orleans, Houston, or Miami—places whose desperate need to change has been recently re-emphasized by the effects of extreme weather events.
Current Debates Surrounding BRT
While BRT has been widely accepted as a safe, effective, and economically beneficial transit investment, there are still debates regarding the practicality of its implementation, especially in cities that can afford other options. Discussions are focused on a variety of subjects, including BRT’s relationship to light rail transit (LRT), whether there is true evidence of urban economic development around BRT infrastructure, and the reality of BRT’s public modal image.
The debate surrounding the true economic benefits of BRT focuses mainly on whether the negative effects of new bus systems outweigh the positives in the immediate vicinity around stations. Heres et al. sum up the argument well:
“In some cases, especially in the immediate vicinity of a new station, public transport may be seen as a negative amenity for the area as the increased noise, crowding, and crime outweigh the positive effect of reduced public transport travel times. If this is the case, then land prices would drop, with a likely associated drop in housing prices (and possibly a decrease in housing unit density as housing is replaced by commercial space).”
Given that the above statement poses a possible outcome, the same study found that “overall, findings have been that where there is a statistically significant effect of public transport on housing prices, it is positive.” The authors demonstrate and prove this claim with the case of the TransMilenio system, and conclude that it holds up in the majority of situations, confirming the fact that despite a handful of side effects, BRT is more often than not an economically positive contributor to the areas it serves.
The economic benefits of BRT are overwhelming; thus, the debate has become less controversial in recent years. However, while the discussion about BRT’s economics weakens, the rhetorical conflict surrounding perceived image is in full force. To most informed planners, BRT’s cost-effectiveness and cuts in travel time are obvious; but whether people truly want a bus traveling down the middle of their street instead of a train—especially if the city can afford Light Rail Transit—is cause for discussion. According to Hensher and Mulley, the answer is normally found in determining the level of development of a given country—there appears to be a strong preference in favor of LRT in developed countries and the reverse in developing countries. This is often due to personal history with a certain mode, as well as perceived affordability.
A Practical Transit Option for Every City?
The fact that BRT’s modal image is seemingly well divided between more developed and less developed regions begs the question of whether the system can be pragmatically established in every place. In developing countries, the answer is undoubtedly yes. The projected population growth for said regions is frankly too substantial not to consider BRT.
As Stokenberga puts it:
“Cities in the developing world are growing at an unprecedented rate and their population is projected to increase by 3.5 billion between 2000 and 2050, accounting for 95% of the increase in the world’s urban population. As the majority of future urban growth is expected to take place in medium-size cities (UN-Habitat, 2011) with limited fiscal capacities, BRT systems are likely to offer an affordable high-quality transit solution (Hensher, 2007), especially when combined with high-quality infrastructure for pedestrians and bicyclists (Suzuki et al., 2013). Moreover, the flexibility and cost effectiveness of BRT make it an excellent choice for cities and transit agencies facing both increasing demand for transit and increasingly constrained budgets.”
In nations where wealth is not abundant and the population is growing exponentially, the offerings of BRT will prove invaluable. Nevertheless, these benefits are not confined to the developing world. The US population is expected to grow by just over 113,000,000 people in the next 35 years; this means large cities becoming larger, mid-size cities becoming large cities, and small cities becoming mid-size cities. If planners and citizens want a bright future that does not include congested freeways and exacerbated carbon emissions they need to broaden their transportation horizons. BRT is an important solution for such a problem, and it should be taken into consideration by every region of the world, developed or developing.
The research, commentaries, and data all support the notion that BRT is an efficient, cost-effective, safe, and sustainable transit option for nearly any metropolitan area that dares to build it. Moreover, it is important to note that the contents in this paper have done little more than scratched the surface of the subject. For example, there are studies discussing the effects of BRT on certain urban forms or the use of the system for promoting pedestrian activity. In short, the case for BRT has many components, and not all of them are included in this paper. The subject is a deeply involved one, and it requires additional research in order for one to have a more comprehensive understanding of its implications.
Despite the overwhelming evidence that BRT is an efficient and cost-effective form of transportation for every region, there a few qualifications to be made concerning its implementation, the most notable being that of practicality. While BRT is an affordable and effective option for nearly every city that has the money and infrastructure to support it, that fact alone does not necessitate that the system be introduced into the public transit system. For example, Racehorse et al. have found that “in the USA and Canada, it is found that ‘BRT is typically successful when the urban population exceeds 75,000 and employment in the central business district (CBD) is, at a minimum between 50,000 and 75,000. Land uses should be organised in dense patterns that facilitate transit use.” Not every city in the USA and Canada fits these criteria; thus, it is reasonable to conclude that not every city in the USA and Canada would have the same success with a BRT system. The same applies to every region of the world. There will always be situations—whether topographic, economic, demographic, or form-based—in which BRT is not the best option. The “best” option will always be unique to needs of the area or municipality in question.
In an ever-growing world with increasingly unique problems regarding transportation, Bus Rapid Transit has come on to the scene as an answer to the prayers of planners. The system’s flexibility and overall conceptual efficiency offer the potential of a sustainable future in the form of reduced carbon emissions, shorter travel times, increased public health, improved road safety, and economic prosperity. It is not a perfect system, and there are still many research gaps to be filled relevant to its benefits and drawbacks; even so, the evidence suggests that it is currently one of the most effective and affordable transit options available for places looking for relief from congestion, especially in coastal cities whose vulnerability to sea level rise. If a city has the funds, the space, and the demand, it would do well to consider BRT for fulfilling part of its transportation needs.
 IPCC, 2014: Summary for Policymakers, In: Climate Change 2014, Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [O. Edenhofer et. Al], 603. From now on this reference will be cited thus: IPCCSPM, #.
 “Global BRT Data,” BRTData, accessed December 2, 2017, http://brtdata.org.
 Aiga Stokenberga, "Does Bus Rapid Transit Influence Urban Land Development and Property Values: A Review of the Literature," Transport Reviews 34, no. 3 (2014): 276.
 Taotao Deng and John D. Nelson, "Recent Developments in Bus Rapid Transit: A Review of the Literature," Transport Reviews 31, no. 1 (2011): 70.
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 Deng and Johnson, 73.
 Ibid., 74.
 Fabio Duarte and Fernando Rojas, "Intermodal Connectivity to BRT: A Comparative Analysis of Bogota and Curitiba," Journal of Public Transportation 15, no. 2 (2012): 3.
 Deng and Nelson, 74-75.
 Duarte and Rojas, 14.
 Ibid., 12-13
 Ibid., 10.
 Janeth Mosquera Becerra, Rodrigo S. Reis, Lawrence D. Frank, Farah A. Ramirez-Marrero, Benjamin Welle, Eugenio Arriaga Cordero, Fabian Mendez Paz, et al., "Transport and Health: A Look at Three Latin American Cities," Cadernos De Saude Publica 29, no. 4 (April, 2013): 660.
 Ibid., 658.
 Juan Pablo Bocarejo, Juan Miguel Velasquez, Claudia Andrea Diaz, and Luis Eduardo Tafur. "Impact of Bus Rapid Transit Systems on Road Safety Lessons from Bogota, Colombia," Transportation Research Record no. 2317 (2012): 3.
 Ibid., 4.
 Ibid., 6-7.
 IPCCSPM, 603.
 Vincent, William, and Lisa Callaghan Jerram. "The Potential for Bus Rapid Transit to Reduce Transportation-Related CO~ 2 Emissions." Journal of Public Transportation 9, no. 3 (2006): 233.
 Zhang, Guo-Qin, Klueh Cas, Shenghui Cui, Hongbin Niu, Wei Wang, Guoqin Zhang, Lijie Gao, and Jianyi Lin. 2010, "Carbon footprint analysis of the Bus Rapid Transit (BRT) system: a case study of Xiamen City," International Journal of Sustainable Development and World Ecology 17, no. 4: 329-337, Science Citation Index, EBSCOhost (accessed December 3, 2017).
 Neumann, Barbara Vafeidis Athanasios T, Zimmermann Juliane, and Nicholls Robert J. n.d. "Future coastal population growth and exposure to sea-level rise and coastal flooding--a global assessment," Plos ONE, Vol 10, Iss 3, P E0118571 (2015) no. 3: e0118571. Directory of Open Access Journals, EBSCOhost (accessed December 3, 2017).
 Stokenberga, 277.
 Ibid., 286.
 R. Cervero and CD Kang, "Bus Rapid Transit Impacts on Land Uses and Land Values in Seoul, Korea," Transport Policy 18, no. 1 (2011): 115.
 David R.Heres, Darby Jack, and Deborah Salon, "Do Public Transport Investments Promote Urban Economic Development? Evidence from Bus Rapid Transit in Bogota, Colombia," Transportation 41, no. 1 (January 2014): 61.
 David Hensher and Corinne Mulley. "Modal Image: Candidate Drivers of Preference Differences for BRT and LRT." Transportation 42, no. 1 (2015): 7.
 Stokenberga, 276-77.
 US Census, Population Projection 2010-2050, census.gov.
 Amy Eyler, Ross Brownson, Tom Schmid, and Michael Pratt, " Understanding policies and physical activity: frontiers of knowledge to improve population health," J Phys Act Health 7, no. suppl 1 (2010): S9-S12.
 Vernon Joseph Racehorse, et al. "Bus rapid transit system deployment for high quality and cost-effective transit service: a comprehensive review and comparative analysis." IET Intelligent Transport System 9, no. 2 (March 2015): 180.