This
mode of transit, formerly known as "trolley", "street railway,"
or "streetcars," has gained popularity in the United States since
the early 1970s with the construction of the San Diego Trolley system.
Many U.S. cities have implemented similar systems to ease urban
congestion and provide for better mobility of its citizens.
The term "light rail" does not signify the weight of the vehicle,
rather, it refers to the operational characteristics of the service
provided. It incorporates advanced developments in rail vehicle
technology with the economical benefit of in-street running where
accessibility to the system is by means of simple wayside platforms
or stations.
Featuring
low capital and maintenance costs it is environmentally and patron
friendly when compared to bus or automobile use. Mostly, light rail
lines are constructed at grade in shared rights-of-way of local
arterial routes. The rail is fastened to continuously supported
concrete track slabs situated below grade level. Here, concrete
provides the necessary long-term durability to the track structure
as well as the rigidity to span buried utilities crossing the rail
lines.
The area between tracks is frequently paved with concrete or concrete
paving blocks to allow other vehicular traffic access to the available
right-of-way. Slab track for this application has many design variations
including the use of cast-in-place and continuously reinforced concrete.
Today, more than eighteen cities are enjoying the benefit of light
rail transit. More important, many other cities are currently considering
the construction of light rail systems.