Commuter
rail operates over freight railroad rights-of-way to downtown railroad
stations. This mode of transit has a significant cost advantage
over other urban rail alternatives such as light or heavy rail.
Furthermore, commuter rail can be planned and implemented more quickly.
In general, construction consists of rehabilitation of an existing
or abandoned rail line where track systems are renewed to foster
smooth running. Such renewals incorporate welded rail on concrete
ties, pre-fabricated concrete grade crossings, and concrete platforms
and stations. Speeds for this mode are generally under 70 mph.
Commuter rail is used to carry passengers to the nation's largest
central business districts. A long history of commuter rail service
dominates the metropolitan areas of New York, Chicago, Boston, Philadelphia,
San Francisco, and Washington-Baltimore.
In recent years, five other metropolitan areas have built commuter
rail lines: Los Angeles, Washington, San Diego, Dallas-Fort Worth,
and Miami-Fort Lauderdale-West Palm Beach. Many other urban areas
are considering implementation of commuter rail on the basis of
its lower capital cost compared to alternate modes, traffic congestion
relief, shorter central business district (CBD) travel times and
air pollution reduction.
Major structures constructed to support these operations include
maintenance facilities, parking garages, and downtown stations that
are of either new or rehabilitated construction.