Understanding the Types of Rail Transit
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Image source: Beyond DC 2014
In the discussion of the varying options of public transit, often multiple types, or modes, of transit are referenced. Sometimes the distinctions between different modes is fairly obvious, most everyone has a good idea of the differences between how a city bus and a subway system look, feel, and work; but some of the differences are more fine grained, for example: what are the differences between a streetcar and light rail system? This section provides readers with a basic understanding of the differences between common rail transit technologies (streetcars, light rail, and heavy rail) and provides an overview of emergent bus rapid transit (BRT) systems.
Streetcar and Light Rail Systems Compared
Both streetcar and light rail systems use the same general type of rail technology. Both systems usually have two or three cars which run on fixed tracks, draw their power from overhead wires, and are operated by an on-board driver (APTA 2014). What distinguishes streetcar and light rail systems is how the technology is applied. The differences in application effect many of the systems' attributes, including: how many passengers a system can accommodate, who the target ridership is, and the total capital and operation costs of the system.
Streetcars function as 'urban
circulators', transporting people for short distances -- generally
within several blocks or between a few neighborhoods. Streetcars also
often function on existing roads, in mixed traffic with automobiles, at
slower speeds than light rail cars. This is because light rail cars
usually function in their own lanes (formally called right-of-ways)
independently of automobile traffic. Because streetcars function in
mixed traffic, their cars are shorter and there are generally less cars
in a streetcar train than in a light rail train; this is to accommodate
the tight turning radii of city streets that streetcars must maneuver.
Shorter cars and trains and slower running times implies that streetcar systems
usually carry less passengers over shorter distances than light rail
systems. Because light rail systems move more passengers more quickly, their system networks often cover greater distances, as the image below shows.
Many modern streetcar systems are compatible with light rail systems, which allows for easy network expansion if it is desired at a later date. For example: portions of the tracks being used in Cincinnati's streetcar systems could also potentially be used to run light rail cars on in the future (Schneider 2013).
Click here for a more comprehensive overview of the differences between streetcar and light rail systems.
Click here for a more comprehensive overview of the differences between streetcar and light rail systems.
The differences between streetcar and light rail systems are subtle.
Image sources: RPR Consulting 2012 (left) and Sound Transit n.d. (right)
Image sources: RPR Consulting 2012 (left) and Sound Transit n.d. (right)
Bus Rapid Transit (BRT) Systems
Bus rapid transit (BRT) systems are an emerging mode of public transit that essentially uses regular buses in a dedicated right-of-way (independent of automobile traffic) to ensure rapid transit. In addition to running in a dedicated lane, BRT systems also: pick up passengers in the center of regular road lanes (thus avoiding curb side delays), have off-board fare collection systems, have priority at traffic intersections over automobile traffic, and have bus floors that are level with station floors (ITDP N.d.).
BRT is sometimes brought up as a low-cost alternative to rail transit, as BRT systems do not involve the capital expense of laying tracks. In Cincinnati, it is often argued that simply expanding the city's bus system, instead of investing in rail transit, would have a similar outcome and save millions (Wetterich 2014).
Click here to learn more about the comparison between regular and BRT bus systems and rail transit systems.
Click here to learn more about the comparison between regular and BRT bus systems and rail transit systems.
Light Rail and Heavy Rail Systems Compared
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Like the differences between streetcar and light rail systems, the differences between light and heavy rail systems are subtle, but important. Heavy rail cars typically move faster and accelerate more quickly than their light rail counterparts (APTA 2014). Heavy rail systems are able to accomplish higher speeds as their cars always operate in an exclusive right-of-ways (such as subway tunnels), on electrified track (with no overhead wire), and use sophisticated signaling systems to further enhance service timing (APTA 2014). Heavy rail systems also usually operate at more frequent intervals than light rail systems (Transportation for America 2012, 13).
As a result of these attributes, heavy rail systems are able to carry more passengers than light rail systems over similar distances. Some of the most famous rail transit systems in the US are technically considered heavy rail systems, such as: the New York City Subway, the Chicago El, and the Washington Metro.
One of the main drawbacks of heavy rail systems is that the capital costs per mile are usually higher than those of light rail systems. Typical costs to create a light rail system range from about $400 million to $2 billion, whereas heavy rail systems start at about $2 billion and can be as costly as $5 billion (Transportation for America 2012, 13). The period of construction typically required to complete a heavy rail system is also considerably longer than a light rail system and heavy rail networks require significant operations and maintenance costs over the life of the system (Transportation for America 2012, 13).
As a result of these attributes, heavy rail systems are able to carry more passengers than light rail systems over similar distances. Some of the most famous rail transit systems in the US are technically considered heavy rail systems, such as: the New York City Subway, the Chicago El, and the Washington Metro.
One of the main drawbacks of heavy rail systems is that the capital costs per mile are usually higher than those of light rail systems. Typical costs to create a light rail system range from about $400 million to $2 billion, whereas heavy rail systems start at about $2 billion and can be as costly as $5 billion (Transportation for America 2012, 13). The period of construction typically required to complete a heavy rail system is also considerably longer than a light rail system and heavy rail networks require significant operations and maintenance costs over the life of the system (Transportation for America 2012, 13).