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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.
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
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.
Portland LRV Photo ©
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.
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
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.
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
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.
Transportation Research Board, This is Light Rail Transit, TRB Publications, 1977,
 Wikipedia: Light Rail
 The Toronto LRT Information Page
Light Rail Transit Association