Light Rail - Categories of Light Rail

Categories of Light Rail

The most difficult distinction to draw is that between light rail and streetcar or tram systems. There is a significant amount of overlap between the technologies, many of the same vehicles can be used for either, and it is common to classify streetcars/trams as a subtype of light rail rather than as a distinct type of transportation. The two general versions are:

1. The traditional type, where the tracks and trains run along the streets and share space with road traffic. Stops tend to be very frequent, but little effort is made to set up special stations. Because space is shared, the tracks are usually visually unobtrusive.
2. A more modern variation, where the trains tend to run along their own right-of-way and are often separated from road traffic. Stops are generally less frequent, and the vehicles are often boarded from a platform. Tracks are highly visible, and in some cases significant effort is expended to keep traffic away through the use of special signaling, level crossings with gate arms or even a complete separation with non-level crossings. At the highest degree of separation, it can be difficult to draw the line between light rail and metros, as in the case of Wuppertal's Schwebebahn hanging rail system or London's Docklands Light Railway, which would likely not be considered "light" were it not for the contrast between it and the London Underground; many consider these not to be "light rail" lines but light metros. However, in Europe, the term light rail is increasingly being used to describe any rapid transit system with a fairly lower frequency or shorter trains compared to heavier mass rapid systems such as the London Underground or the Mass Rapid Transit in Singapore. For instance, the Yellow Line and Blue Line in Manila are often referred to as "light rail", despite being fully segregated mostly-elevated railways. In North America, such systems are not considered to be light rail.

Many light rail systems—even fairly old ones—have a combination of the two, with both on-road and off-road sections. In some countries (esp. in Europe), only the latter is described as light rail. In those places, trams running on mixed right-of-way are not regarded as light rail, but considered distinctly as streetcars or trams. However, the requirement for saying that a rail line is "separated" can be quite low—sometimes just with concrete "buttons" to discourage automobile drivers from getting onto the tracks.

There is a significant difference in cost between these different classes of light rail transit. The traditional style is often less expensive by a factor of two or more. Despite the increased cost, the more modern variation (which can be considered as "heavier" than old streetcar systems, even though it is called "light rail") is the dominant form of urban rail development in the United States.

Some systems, such as the AirTrain JFK in New York City and DLR in London and Kelana Jaya Line in Kuala Lumpur, Malaysia have dispensed with the need for an operator. The Vancouver SkyTrain was an early adopter of driverless vehicles, while the Toronto Scarborough rapid transit operates the same trains as Vancouver, but uses drivers. In most discussions and comparisons, these specialized systems are not considered to be light rail.