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The Transportation Research Board defined (1977) Light Rail 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.[1]

Although many definitions are used, we like this one because it highlights the flexibility of Light Rail Transit (LRT) systems. It is useful to look at the two extremes that can be considered:

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. [2]

Portland LRV   Photo ©   Lightrail Central

A range of trade-offs is offered from the lower cost and performance of the first option to where, as one approaches the second option, there may be little distinction from the high cost and performance of "metro" or "subway" systems that are now called "Heavy Rail".

Note that "light" and "heavy" in this context generally refers to the intended passenger traffic rates. It does not refer to the weight of the vehicles, since Light Rail Vehicles (LRV's) are often heavier than metro cars due to the need for more side impact protection in flexible environments. Nor does the terminology necessarily refer to the rail itself, although LR systems may tolerate poorer rail due to limited speeds.[3] 

Speed Limitation is an important distinction.  In addition to delays resulting from potentially mixed environments, LRT systems have moderate peak speed goals, in the range of 70 to 80 kph (43.5 to 50 mph) compared with metro goals approaching 160 kph (100 mph).  In addition to the lower rail quality requirements, this also may reduce the cost of vehicles, power connections, and system design and construction.


With the popularity explosion of the private automobile, the use of streetcars or trolleys declined during the twentieth century, particularly in the United States. The bus was seen as more compatible with the automobile for most urban public transportation, and the highest density centers invested in subways. Some use of streetcars continued, particularly in Northern and Eastern Europe, where new advanced vehicle designs  gradually emerged.[4]

During the late twentieth century pollution and energy concerns have motivated a return to the streetcar, now baptized as "Light Rail" to emphasize the use of the modern vehicle technology and better practices.

Historic trolley in Halle an der Saale, Germany
Photo © Gebruiker:Markv  Wikipedia


This website is not a professional guide, but an editing of existing referenced material for educational purposes. The website author assumes no responsibility for any problems resulting from using the material presented in this website.

[1] Transportation Research Board, This is Light Rail Transit, TRB Publications, 1977, Washington, DC.

[2] Wikipedia: Light Rail

[3] The Toronto LRT Information Page

[4] Light Rail Transit Association