Definition: Light Rail

Light Rail is essentially a modern evolution of the conventional trolley. The concept evolved largely in the German and Dutch speaking countries of Europe in the decades after World War II. In this era cities in the U.S., Canada, the U.K., and France, among other countries, replaced their streetcars with buses, but in the German and Dutch-speaking countries the streetcars were retained and upgraded.

The Transit Research Board definition is: "Light rail transit is a metropolitan electric railway system characterized by its ability to operate single cars or short trains along exclusive rights of way at ground level, on aerial structures, in subways or, occasionally, in streets, and to board and discharge passengers at track or car-floor level."

Key characteristics that distinguish light rail from streetcars are the following:

• Track is segregated from traffic wherever possible enabling higher operating speeds. Track is normally placed in reserved lanes on streets, in separate reservations on or next to streets, on private right of way similar to railroad lines, in subways, or on elevated structures. But the lines can still negotiate sharp curves and steep grades, similar to streetcar lines.
• Station spacing is usually further apart than on streetcar lines, again to allow increased operating speed. Stations are also typically more formally defined than on streetcar lines, often featuring shelters, seating, passenger information, and fare machines.
• Cars are normally longer and more spacious. Most today are articulated, meaning that they are made of several body sections connected by a flexible joint that allows lengthy cars to bend as they negotiate sharp curves and steep grades. These cars will often run in trains of two to four cars coupled together.
• Traditionally boarding of light rail cars, as with streetcars, is via steps from a low platform. However, several new light rail systems have opted for high platforms level with the car floor. The latest trend is to use cars specially built with the floor over some or all of the length of the car lowered to about 12 inches from the top of the rail, providing ADA compliant accessibility from relatively low platforms and speeding boarding and alighting for all passengers.
• Fares are often not collected on cars, to enable boarding through many doors without a staff member collecting fares at the door, and to speed loading. Modern systems typically use an honor system requiring purchase of a ticket before boarding the car and use fare inspectors to verify compliance randomly.

A modern light rail train in downtown Baltimore.

Light rail systems are normally less expensive to build than heavy rapid transit systems (see Heavy Rail) as they require less and simpler infrastructure. Light rail lines can carry more passengers through a given corridor than buses or streetcars, but fewer than a heavy rapid transit system.

Surviving trolley systems in cities such as Boston, Pittsburgh, and San Francisco have been upgraded to light rail status in recent decades. Since 1981 many completely new light rail systems have been built in cities such as San Diego, Portland (OR), Buffalo, Baltimore, St. Louis, and Dallas to name just a few.

For further discussion of the differences between streetcars and light rail refer to the following brochure: Light Rail and Streetcar Systems - How They Differ; How They Overlap..