Light Rail Transit

Light rail, light rail transit (LRT) or fast tram is urban public transport using rolling stock similar to a tramway, but operating at a higher capacity, and often on an exclusive right-of-way.

There is no standard definition, but in the United States, where the terminology was devised in the 1970s (from the engineering term light railway), light rail operates primarily along exclusive rights-of-way and uses either individual tramcars or multiple units coupled to form a train.

A few light rail networks tend to have characteristics closer to rapid transit or even commuter rail; some of these heavier rapid transit-like systems are referred to as light metros. Other light rail networks are tram-like in nature and partially operate on streets. Light rail systems are found throughout the world, on all inhabited continents. They have been especially popular in recent years due to their lower capital costs and increased reliability compared with heavy rail systems.

The term light rail was coined in 1972 by the U.S. Urban Mass Transportation Administration (UMTA; the precursor to the Federal Transit Administration) to describe new streetcar transformations that were taking place in Europe and the United States. In Germany the term Stadtbahn (to be distinguished from S-Bahn, which stands for Stadtschnellbahn) was used to describe the concept, and many in UMTA wanted to adopt the direct translation, which is city rail (the Norwegian term, bybane, means the same). However, UMTA finally adopted the term light rail instead.Light in this context is used in the sense of "intended for light loads and fast movement", rather than referring to physical weight. The infrastructure investment is also usually lighter than would be found for a heavy rail system.

The Transportation Research Board (Transportation Systems Center) defined "light rail" in 1977 as "a mode of urban transportation utilizing predominantly reserved but not necessarily grade-separated rights-of-way. Electrically propelled rail vehicles operate singly or in trains. LRT provides a wide range of passenger capabilities and performance characteristics at moderate costs."

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