By Neal Humphrey
In order to investigate the potential growth of public transit for the creation of a more sustainable transit paradigm, this paper seeks to explore the features of a Bus Rapid Transit (BRT) system, and compare them to the costs and benefits of other public transit options. BRT is often viewed as an intermediary transit option, providing many of the benefits of light rail systems that normal buses cannot provide, yet doing so with reduced cost and, therefore, greater potential service. As growing cities seek to meet their transit needs, Bus Rapid Transit can provide many of the benefits of both light-rail and bus services and as such may prove to be the most effective public transportation option in many communities.
This paper presents the five main components comprising the definition of a BRT system, as summarized from a variety of presentations. It discusses the implementation of these five components, related costs, and potential benefits. Importantly, it provides context of why a BRT system must be viewed as separate from a standard bus system. BRT systems can be a valuable tool to broaden public transportation accessibility, increasing the sustainability of our increasingly urban population.
In order to explore the potential growth of public transit for the creation of a more sustainable transit paradigm, this paper seeks to explore the features of a Bus Rapid Transit (BRT) system, and compare them to the costs and benefits of other public transit options. BRT is often viewed as an intermediary transit option, providing many of the benefits of light-rail systems that normal buses cannot provide, yet doing so with reduced cost and, therefore, greater potential service (Wright, p. 10). As growing cities seek to meet their transit needs, Bus Rapid Transit can provide many of the benefits of both light-rail and bus services and as such may prove to be the most effective public transportation option in many communities.
Bus Rapid Transit
There is no complete consensus as to what constitutes Bus Rapid Transit. In some situations, it may most accurately be described as simply efficiency improvements to existing bus systems. Under other situations, it can be more accurately described as a rubber-tired light rail transit system (Levinson, 2003, p. S-1). In understanding the basic goal of BRT design without technical detail, the Federal Transit Administration definition may be best: "a rapid mode of transportation that can combine the quality of rail transit and the flexibility of buses" (Levinson, 2003, p. 23).
There is often much discrepancy in the technical components of BRT, with some systems incorporating all design components and others with only partial implementation. This has sometimes proved to be an obstacle in effective implementation of BRT as some cities have branded marginal improvements as BRT—undermining the integrity of the fundamental definition through which the benefits of BRT can be realized (Sheehan, 2007, p. 81).
Due to this discrepancy, an exact technical definition of BRT is difficult to provide. The only fundamental requirement for a BRT system is the use of rubber-tired vehicles with the goal of a rapid-transit system. The features of a typical BRT system may be summarized into five overlapping categories, adapted from various definitions:
- Exclusive lane use or lane priority and traffic signal priority
- Boarding and fare collection improvements
- Stop spacing and improved stations/shelters
- Intelligent Transportation System technologies (computer-aided controls for vehicle spacing and passenger notification of time of next bus arrival)
- Improved, specialized vehicles
BRT has a central focus on the customer, being designed around the customer needs of speed, comfort, convenience, cost, and safety rather than a particular technology (Wright, n.d., p. 11). Individual technologies meet these goals for an end result of a better transit system and thus more riders. BRT is also marketed with a strong image and identity, (United States Federal Transit Administration, 2003, p.12) which is another technique aimed at increasing use. This image is a strong component in evaluating BRT systems--especially in the American context--as it is an important part of ensuring the social success of the system. American public transit has a strong negative stigma, especially bus transit, which needs to be overcome.
Lane Use and Traffic Flow
The primary goal of BRT is to minimize transit time and maximize the number of people moved. Arguably the most important component for meeting this goal is through the methods of bus-priority in traffic flow, especially in areas competing with significant highway congestion. Bus Rapid Transit flow can be either integrated into existing roads or, more closely mimicking light rail, exist on exclusive busways.
The degree of segregation from regular traffic is the primary parameter in designing a BRT running way (Booz Allen Hamilton, 2004, p. 45). BRT vehicles can potentially operate with no separation from traffic on existing streets or highways. This offers little differentiation from standard bus transportation systems, and does little to realize the benefits of BRT. However, for systems using roadways, a 'queue jumper' lane can be used to increase effectiveness (Booz Allen Hamilton, 2004, p. 46). This is typically a short section of road on the approach to a busy intersection that allows the bus to bypass stopped traffic in the approach to the intersection. Costs for queue lanes are between $0.1 and $0.29 million per intersection (Booz Allen Hamilton, 2004, p. 46).
Alternately, a reserved bus lane may be incorporated into existing streets. There are many different types, whose use can be determined by space considerations, cost, needs, and local preference. The most basic upgrades from basic bus transit systems involve a curbside lane on arterial streets or a shared high occupancy vehicle (HOV) lane on highways. Curbside bus lanes are the easiest and cheapest to install, but it is often difficult to enforce the restriction on maintaining the bus-only use, which can be a cause of delays (Levinson, 2003, p. S-5). Additionally, when integrating these bus lanes into general traffic flow, right-hand turns in the bus lane are typically allowed; this can be another source of delays when buses conflict with cars (Levinson, 2003, p. 3-11).
Another basic method of incorporating buses into existing street traffic is through the use of contra-flow bus lanes. This typically occurs in denser city areas, as it is placed along one-way streets. Using contra-flow lanes is beneficial because it decreases traffic conflict, as the bus-only restriction is self-enforcing (Levinson, 2003, p. 3-13). Although there are typically fewer accident problems with other cars, provided sufficient lane distinction, there can be accident problems with pedestrians. Typically, pedestrians recognize the street as one-way, and fail to recognize the 'wrong-way' operation of buses along the route (Levinson, 2003, p. 3-13).
Of all the methods of incorporating bus rapid transit into existing streets, the most effective method is through the use of median-integrated busways. These systems operate on two-way streets, with the bus lanes and bus stops for both directions incorporated into the median of the road. This is the method employed in such systems as Bogota, Colombia; Curitiba, Brazil; Cleveland, Ohio; and Eugene, Oregon (Levinson, 2003, S-4). In particular, the South American systems in Bogota and Curitiba are those that have achieved the most success in implementing these systems. The typical function of such a system can be seen here in Figure 1.
Median-integrated busways eliminate passenger loading, curb access, and right-turn problems associated with the curb-type lanes (Levinson, 2003, p. 3-18). As can be seen in the figure, the bus stops alternate between directions, utilizing the median space allocated. Median-integrated systems require wide roadways, typically at least 90 to 100 feet (Levinson, 2003, p. 3-18). Also, they pose problems dealing with left-turns of the general traffic and with pedestrian access to the median. Costs for road-integrated systems range from $2.5 and $2.9 million per lane-mile, depending on the system type and local conditions (Booz Allen Hamilton, 2004, p. 2-4).
Rather than integrate BRT into roads with common traffic, a second option is to employ exclusive busways, either at-grade or grade-separated. In suburban situations, these can be built alongside existing highways, while in urban settings it can mean a reassignment of particular streets to be bus-only. This method is separated into two types: at-grade or grade-separated. At-grade systems cost between $6.5 million and $10.2 million, (Booz Allen Hamilton, 2004, p. 2-5) and of course are space dependent.
Fully grade-separated systems can achieve the most speed and efficiency, but with the highest cost. These systems most closely mimic light rail, with complete right-of-way separated from congestion at intersections and on adjacent highways. For above-grade busways, costs range from $12 to $30 million per lane mile, and below-grade (similar to subway tunnel systems) from $60-$105 million per lane mile. Additional lanes cost between $2.5 and $3 million above-grade and $6.5 to $10.12 below grade per additional lane mile (Booz Allen Hamilton, 2004, p. 2-5). These busways can dramatically impact performance. The Adelaide BRT system operates at a very high average speed of 80 kph (50 mph), including stopping time. This includes maximum running speeds of 100 kph (62 mph) (Currie, 2006, p. 2). This speed is largely due to the use of a guided busway, which uses optical guidance along the busway track to enable faster speeds. Typical BRT systems operating on busways can achieve average speeds of 30 mph including stops (Levinson, 2003, p. 29).
Vehicle right-of-way is a crucial component to Bus Rapid Transit. Of the 29 systems surveyed in the Transportation Research Board's Case Studies in BRT, 24, or 83%, used dedicated running ways—either a bus-only road or bus lane (Levinson, 2003, p. 3). To provide speeds that are competitive with driving, and thus enable passengers to switch to public transit, BRT should operate off-street busways (Levinson, 2003, p. 29).
A big advantage of BRT is its ability to incorporate a mix of these different lane-priority systems depending on location. Queue jumpers can be used when road space is at a premium and buses are less frequent, while on the same line buses can move into a median-integrated busway later as space permits. In contrast with a light rail system, passengers can board a BRT vehicle that is operating in normal road conditions in suburban areas, but which later enters an exclusive busway on the approach to an urban center (Breakthrough Technologies Institute, 2007, p. 3).
Boarding and Fare Collection
In order to decrease stop time and increase transit speed, Bus Rapid Transit seeks to maximize boarding efficiency, especially in locations where many passengers board at once. This is done through three main techniques: fare collection, level boarding, and multiple boarding doors.
The best BRT stations ensure that passengers pay their fare before entering the station (Breakthrough Technologies Institute, 2007, p. 2). By pre-paying, customers can enter buses through multiple bus doors, increasing the efficiency of boarding. Also, many BRT systems utilize level-boarding, mimicking boarding on light-rail systems. In level boarding designs, a boarding platform or raised curb is built at the stop—to a height of around 14 inches—in order to match the floor height of low-floor vehicles (Booz Allen Hamilton, 2004, p. 2-17). Additionally, it is necessary to have a method to bring the bus sufficiently close to the platform. This can be accomplished through optical guidance, electromagnetic guidance, or mechanical systems (Kantor, Moscoe, & Henke, 2006). Not only do guidance systems improve boarding efficiency, but they also help to improve public perception by further separating a BRT system from a standard bus system.
Clearly, these methods of improved boarding and fare collection require more developed stations than typical bus stops. In addition to the improvements of level boarding and fare collection, BRT stations provide a seamless, sheltered connection to the vehicles (Breakthrough Technologies Institute, 2007, p. 2). Figure 2 shows an example of a BRT station, with bus 'docked' at the platform. Commuter stations often offer bicycle storage and park-and-ride facilities, as appropriate. Having fully developed, complete stations improves the image of BRT, helping to encourage public acceptance of the system. Along with dedicated busways, station design that mimics rail is a key component in distinguishing BRT from standard bus transit. Station cost is highly dependent on system design.
Intelligent Transportation System Technologies
The primary ITS technology employed by BRT is the docking-guidance discussed in the boarding and fares section, as well as similar technology used, for example, in the Adelaide busway to achieve the high speeds of that system. However, another key feature of BRT systems can be ITS systems that track bus locations, providing vehicle arrival information (Breakthrough Technologies Institute, 2007, p. 3). BRT systems will send this information to stations, alerting passengers of the next bus arrival time, and potentially make the information available via cell phone.
BRT vehicles should be designed to match the stations that they serve. Articulated buses—which allow for more passengers—are often used, and wide aisles are also beneficial (Levinson, 2003, p. S-10). In addition to these functionality considerations, which aim to increase the passenger capacity and ease of use, BRT buses are often designed to look distinctive from normal buses, again contributing to the image component of BRT overall system design.
The costs of a BRT system are highly variable and are mostly dependent on the traffic pattern used. Typical BRT systems vary in cost from around $800,000 to $24 million per mile (Wright, n.d., p. 27). By comparison, most light rail systems cost between $22 and $64 million per mile, while elevated and underground systems can cost much more. Operating costs can vary between the two alternatives, typically favoring light rail, but the investment cost often comprises the bulk of cost considerations. It is important to note that the best BRT systems can provide equal or better service in terms of transportation time, although there may be a small sacrifice in comfort. These systems would fall in the mid- to upper- range of the BRT cost, while those in the lower range would have services somewhere between rail and standard bus systems.
The Transit Cooperative Research Program (TCRP) found, through its survey of BRT systems, that for application in the US and Canada, "BRT is typically most successful when the urban population exceeds 750,000 and employment in the central business district (CBD) is, at a minimum, between 50,000 and 75,000. Land uses should be organized in dense patterns that facilitate transit use (Levinson, 2003, p. S-2)." These are similar requirements as those for a light-rail system. The flexibility of BRT, however, can potentially offer improved service for a similar city configuration over light-rail as it can bring in buses from more spread out suburban areas and onto a central commuter busway without line changes.
When looking at public transportation improvement options, city planners should strongly consider Bus Rapid Transit systems and the benefits they afford. BRT can offer the speed, comfort, and capacity of a light-rail system at a significantly lowered cost. The flexibility of BRT can allow this system to be more completely integrated into the whole trip of the passenger, allowing for more dynamic usage between urban and suburban areas.
City planners should be careful not to view BRT as simply an improved bus system but rather as a distinct option for transit development. By integrating limited BRT components, a system may not be able to overcome its association with standard bus transport and therefore be unable to realize the benefits of BRT. A dynamic approach to designing the BRT system should be taken, with a strong consideration for the potential passenger's view of the system rather than simply its technical functionality.
BRT can offer a significant public transportation alternative to cities that might not be able to justify the cost of a light rail system, while offering the potential for increased capacity in cities where light rail is being considered. BRT use can help to promote a shift to public transport use, increasing the sustainability of our increasingly urban population.
Booz Allen Hamilton. (2004). Characteristics of Bus Rapid Transit for Decision-Making. Washington, D.C.: Federal Transit Administration.
Breakthrough Technologies Institute. (2007). BRT Fact Sheet. Breakthrough Technologies Institute.
Currie, G. (2006). Bus Rapid Transit in Australasia: Performance, Lessons Learned and Futures. Journal of Public Transportation, Vol. 9, No. 3 .
Kantor, D., Moscoe, G., & Henke, C. (2006). Issues and Technologies in Level Boarding Strategies for BRT. Journal of Public Transport, Vol. 9 No. 3 .
Levinson, H. S. (2003). Bus Rapid Transit - Implementation Guidelines. Vol 90 v.2. 2003: Transportation Research Board.
Rendón, David Alejandro. (2009). BRT Santiago de Cali Colombia. Retrieved 3 March 2010 from: commons.wikimedia.org/wiki/File:BRT,_santiago_de_Cali_station.jpg
Sheehan, M. O. (2007). State of the World 2007 Our Urban Future: A Worldwatch Institute Report on Progress Toward a Sustainabel Society. 1st ed. New York: W.W. Norton & Co.
Gardner, G., Cornwell, P.R., & Cracknell, J.A. (1991). Research Report 329: The Performance of Busway Transit in Developing Cities. Crowthorne, UK: Transport and Road Research Laboratory.
United States Federal Transit Administration. (2003). Bus Rapid Transit - Case Studies in Bus Rapid Transit, Vol. 90 v.1. Washington, D.C.: National Academy Press.
Wright, L. (n.d.). Sustainable Transport: A Sourcebook for Policy-Makers in Developing Cities. Vol. Module 3b: Bus Rapid Transit. Washington, D.C.: Institute for Transportation and Development Policy.
Neal Humphrey is interested in all aspects of sustainability, with a particular focus on energy issues and energy policy. He has dual degrees from NC State in Mechanical Engineering and Science, Technology and Society with a specialty in Sustainability. His professional career has centered on building energy efficiency. He is currently transitioning to a new position at the Alliance to Save Energy, promoting energy efficient windows through their Efficient Windows Collaborative.
 Lloyd Wright's introduction points out the deficiency of many bus systems in reliability, convenience and safety. He describes the typical alternative as being light rail systems, which can meet these deficiencies but with great cost. This large cost means cities can afford less complete service coverage. BRT's lower cost solution to bus transit problems allows for wider applicability. Many reports reviewed expressed similar sentiments.